Dot 20Papers

Dot Papers ………………



1809 references



The search: random dot or random dots or random-dot or random-dots in

the database(s) PsycINFO(All years) and Web Of Science (All Years).









Abadi, R. V. and M. Pantazidou (1997). “Monocular optokinetic nystagmus in humans with age-related

maculopathy.” British Journal of Ophthalmology 81(2): 123-129.

Aim--To investigate full field monocular optokinetic nystagmus (OKN) in patients with age-

related maculopathy (ARM) and relative central scotoma.Methods--Six patients aged 59-88

years with bilateral ARM and an aged-matched control group of six patients aged 54-83 years

were examined. Visual fields were assessed with a Humphrey field analyser using the

threshold 30-1 routine. Monocular full field horizontal optokinetic stimuli were presented on a

hemicylindrical screen subtending 172 degrees horizontally and 50 degrees vertically. The

stimulus was a projected random dot pattern and three stimulus velocities were used, 30, 50,

and 70 degrees/s in both nasalward and temporalward directions. Each trial lasted between 30

and 40 seconds and eye movements were monitored using infrared oculography.Results--The

ARM patients had relative central scotomas with an average depth of 10 dB. Neither the ARM

nor the age-matched groups displayed any directional preponderance or a buildup of the slow

phase eye velocity with time. No statistically significant difference in the gain was found

between the two groups (p>0.05).Conclusions--Marked central field loss in ARM does not

significantly impair OKN gain. This supports the view that complete central retinal integrity is

by no means essential and that the peripheral retina provides an important input to the

generation of OKN.



Adler, B., O. Bock, et al. (1981). “Alpha-stripes: A spatial periodicity appearing in stroboscopically

illuminated moving random dot patterns.” Vision Research 21(6): 913-924.

Demonstrated in 8 adults that when the center of gaze was fixed and a stroboscopically

illuminated dot pattern was moved at constant speed across the visual field, a stationary

striatum appeared oriented perpendicular to the movement direction (alpha stripes, ASs). The

spatial period of the ASs depended on speed and flash frequency. Below 9.5 flashes/sec, no

ASs were seen. The visibility of ASs increased with frequency from 10 to 30 flashes/sec, with

the number of flashes in a train from 3 to 15, and with the number of simultaneously visible

ASs. Up to a coefficient of variation of 0.4, a random variation in the flash intervals (constant

average flash rate, Gaussian interval distribution) did not abolish the visibility of ASs. A

simple model explaining the generation of ASs is discussed. (31 ref) (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 763 of 887 in PsycINFO 1978-1984



Adler, B., O. Bock, et al. (1981). “Alpha-Striation - a Spatial Periodicity Appearing in Stroboscopically

Illuminated Moving Random Dot Patterns.” Behavioural Brain Research 2(2): 239-240.



Adler, B., O. Bock, et al. (1981). “Alpha-Stripes - a Spatial Periodicity Appearing in Stroboscopically

Illuminated Moving Random Dot Patterns.” Vision Research 21(6): 913-924.



Aiello, A., K. W. Wright, et al. (1994). “Independence of Optokinetic Nystagmus Asymmetry and

Binocularity in Infantile Esotropia.” Archives of Ophthalmology 112(12): 1580-1583.

Objective: Children with congenital esotropia, amblyopia, or early visual deprivation have

persistent asymmetric monocular pursuit, as measured by optokinetic nystagmus (OKN), and

favor targets moving in a temporal to nasal direction. Previous studies suggest that binocular

visual development is necessary for the development of symmetric monocular OKN. We

recently treated patients with congenital esotropia with unconventionally early surgery to

establish good binocularity. We wished to determine if mature symmetric OKN responses

could develop in patients with congenital esotropia following the acquisition of good

stereopsis.Methods: Electro-oculographic recordings documented horizontal eye movements

in response to an electronic OKN stimulus.Patients: The recordings of three patients with

congenital esotropia that had been surgically aligned before age 20 weeks and who had

achieved high-grade stereopsis with random dot and Titmus stereographic testing were

studied. We compared this group of children with groups of age-matched controls, including

the following: (1) three patients with congenital esotropia who underwent surgical alignment

after age 6 months and who had no amblyopia bur poor stereopsis; (2) three children with

accommodative esotropia, good ocular alignment when wearing spectacles, and good

stereopsis; and (3) three normal children.Results: The normal children and those with

accommodative esotropia demonstrated normal symmetrical OKN. The patients with

congenital esotropia showed poor nasal to temporal OKN regardless of the degree of

stereopsis or timing of surgery.Conclusions: Our results indicate that good binocularity, as

measured by stereopsis, is not sufficient for the development of symmetric OKN in patients

with congenital esotropia.



Alais, D. and R. Blake (1999). “Grouping visual features during binocular rivalry.” Vision Research

39(26): 4341-4353.

During binocular rivalry, portions of one eye's view may be perceptually dominant while other

portions are suppressed; at any given moment, overall dominance often resembles a patchwork

mixture of the two eyes' views. This study investigates the potency of two Gestalt grouping

cues - good continuation and common fate - to promote synchronous fluctuations in

dominance of two, spatially separated rival targets. Two grating patches were presented to the

left eye paired dichoptically with random-dot patches presented to corresponding right eye

locations. The orientations of the two gratings were either collinear, parallel or orthogonal.

Gratings underwent contrast modulations that were either correlated (identical contrast

changes) or uncorrelated (independent contrast changes). Over 60 s trials, observers pressed

one key when the left grating predominated, another when the right grating predominated and

both keys when both were concurrently visible. Correlated contrast modulation promoted joint

grating predominance relative to the uncorrelated conditions, an effect strongest for collinear

gratings. Joint predominance depended strongly on the angular separation between gratings

and the temporal phase-lag in contrast modulations. These findings may reflect neural

interactions subserved by lateral connections between cortical hypercolumns. (C) 1999

Elsevier Science Ltd. All rights reserved.



Alais, D., M. J. van der Smagt, et al. (1995). “The perceived direction of textured gratings and their

motion aftereffects.” Perception 24(12): 1383-1396.

Examined the perceived directions of obliquely translating textured gratings and the motion

aftereffects they generated. Three observers viewed square-wave luminance gratings with an

array of small random dots covering the high-luminance regions. When Ss were required to

judge the direction of textured gratings moving obliquely relative to their orientation, they did

so accurately. When Ss were required to judge the direction of an obliquely moving textured

grating during a period of adaptation and then the direction of the MAE immediately

following adaptation, these directions were not directly opposite each other. MAE directions

were always more orthogonal to the orientation of the adapting grating than the corresponding

direction judgments during adaptation. (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 386 of 887 in PsycINFO 1993-1995



Alais, D., M. J. vanderSmagt, et al. (1995). “The perceived direction of textured gratings and their

motion aftereffects.” Perception 24(12): 1383-1396.

The stimuli in these experiments are square-wave luminance gratings with an array of small

random dots covering the high-luminance regions. Owing to the texture, the direction of these

gratings, when seen through a circular aperture, is disambiguated because the visual system is

provided with an unambiguous motion energy. Thus, the direction of textured gratings can be

varied independently of grating orientation. When subjects are required to judge the direction

of textured gratings moving obliquely relative to their orientation, they can do so accurately

(experiment 1). This is of interest because most studies of one-dimensional motion perception

have involved (textureless) luminance-defined sine-wave or square-wave gratings, and the

perceived direction of these gratings is constrained by the aperture problem to be orthogonal

to their orientation. Thus, direction and orientation have often been confounded. Interestingly,

when subjects are required to judge the direction of an obliquely moving textured grating

during a period of adaptation and then the direction of the motion aftereffect (MAE)

immediately following adaptation (experiments 2 and 3), these directions are not directly

opposite each other. MAE directions were always more orthogonal to the orientation of the

adapting grating than the corresponding direction judgments during adaptation (by as much as

25 degrees). These results are not readily explained by conventional MAE models and

possible accounts are considered.



Alexander, K. R., D. J. Derlacki, et al. (1999). “Coherence and the judgment of spatial displacements in

retinitis pigmentosa.” Vision Research 39(13): 2267-2274.

We used a motion coherence paradigm to test the hypothesis that patients with retinitis

pigmentosa (RP) have difficulty discriminating the direction of spatial displacements because

of a random loss of motion-sensitive units owing to cone photoreceptor dropout. Minimum

(D-min) and maximum (D-max) displacement thresholds of patients with typical RP or Usher

syndrome were compared with those of age-similar, visually normal subjects. Two-frame

random dot cinematograms were used, in which a group of target dots, which comprised 40-

100% of the dot array in steps of 20%, were displaced in one of four directions, whereas the

non-target dots were randomly repositioned between frames. Reducing the dot coherence in

this way increased D-min and reduced D-max for both the RP patients and control subjects.

Furthermore, the displacement thresholds of the RP patients were displaced laterally from

normal along a log coherence axis, consistent with the hypothesis that the patients had a

reduced effective (intrinsic) coherence. However, the displacement thresholds of control

subjects, when measured at a reduced coherence, did not mimic those of RP patients at full

coherence when both groups were tested with a range of dot contrasts and dot areas. These

apparently discrepant findings can be reconciled if it is assumed that the patients' effective

coherence varies with stimulus visibility. (C) 1999 Elsevier Science Ltd. All rights reserved.



Alexander, K. R., D. J. Derlacki, et al. (1998). “Discrimination of spatial displacements by patients

with retinitis pigmentosa.” Vision Research 38(8): 1171-1181.

We compared maximum displacement thresholds (D-max) with minimum displacement

thresholds (D-min) in patients with retinitis pigmentosa (RP) in order to characterize the

nature of their visual disability, as well as to assess possible models of foveal vision loss.

Thresholds for discriminating the direction of the spatial displacement of random dot patterns

were measured in a group of 20 patients with typical RP or Usher syndrome whose visual

acuities were 20/40 or better and who had minimal or no clinical evidence of changes in the

ocular media. Findings were compared,vith those from an age-similar group of 15 visually

normal subjects, Displacement thresholds were measured using a two-frame random dot

cinematogram and a four-alternative forced-choice procedure. Measurements were made at

each of three dot contrasts and three dot sizes. For the patients with RP, reducing either the dot

contrast or dot size increased D-min and decreased D-max such that the range of discriminable

displacements became considerably restricted, even at modest reductions in dot contrast or

size. This restriction in the displacement thresholds of the patients with RP was correlated

significantly with their visual acuity. By comparison, the control subjects showed little change

in either D-min, or D-max under these conditions. These results indicate that patients with RP

who have only relatively minor reductions in their visual acuity can have severely

compromised motion perception. The pattern of findings suggests that an abnormal contrast

response of the foveal cone system is a major determinant of the impaired displacement

thresholds of these patients with RP. (C) 1998 Published by Elsevier Science Ltd. All rights

reserved.



Alkhateeb, W., J. M. Bromley, et al. (1992). “Abnormal Responses to Multielement Spatial Stimuli in a

Subject with Visual Form Agnosia.” Clinical Vision Sciences 7(3): 163-173.

1. We report measurements on a single patient, HJA, who has exhibited visual form agnosia

since suffering a stroke. He has bilateral neural damage in the region of the occipital lobe

served by the posterior cerebral artery.2. He performs certain visual tasks normally; these

include detection of depth in random dot stereograms, eye movements made in tracking

moving targets, brightness matching between adjacent stimuli, identification of direction of

movement and description of a number of visual illusions.3. He has reduced sensitivity for

detection of grating contrast and of an incremental flash, and he has no wavelength

discrimination for small (2-) fields, viewed foveally.4. We have recorded response times for

his detection of a single target embedded in a number of identical, non-overlapping

background elements. His responses for detection of a line which differs in orientation from

the background lines are normal, which establishes that he can perform such search tasks.5.

His detection of a 2-D target element, distinguished from the background elements by

orientation, magnification, texture, shape or luminance is in every case abnormally slow, and

he requires, on average, ten times longer than normal for detection of such targets.6. He

frequently fails to detect 2-D targets, and the failure rates for different targets correlate closely

with the response times required for their detection. Identification of "null" stimuli which

contain no target is, however, achieved with normal accuracy.7. Measurements with different

numbers of background elements establish that HJA suffers a specific loss in the processing of

multi-element stimuli. He does not, however, exhibit "tunnel" vision.8. We argue that failure

to process normally stimuli containing multiple elements is a critical feature of HJA's visual

performance, and that it leads to disruption of his ability to recognise complex images. We

discuss the neural correlates of his visual dysfunction.



Allik, J. (1992). “Competing Motion Paths in Sequence of Random Dot Patterns.” Vision Research

32(1): 157-165.

Global motion perception from a sequence of random dot patterns has been studied by means

of the competition technique which consists of making a normally less salient motion path in a

superimposed multiple-path stimulus more powerful by adding luminous energy to elements

forming this path. The perceived motion direction of a sequence of random dot patterns can be

dramatically changed by increasing luminance of some fraction of dots leaving all spatial and

temporal intervals between dots unchanged The threshold luminance increment DELTA-I that

is required in order to change the perceived motion direction indicates that differently oriented

local motion vectors are resolved into a single common motion vector along which the whole

pattern appears to move. An inverse spatial proximity rule was discovered: within a certain

spatial limit the motion strength of a particular motion path is proportional to the distance

between stimulus elements forming this path.



Allik, J. and A. Pulver (1995). “Contrast Response of a Movement-Encoding System.” Journal of the

Optical Society of America a-Optics Image Science and Vision 12(6): 1185-1197.

The ability to identify the direction of apparent motion in a sequence of two short light pulses

of different amplitudes at separate spatial locations was studied. The product of pulse

amplitudes is a very poor predictor of such performance when one of the two signals is much

higher in amplitude than the other: above a certain amplitude the probability of correct

identification becomes virtually independent of the amplitude of the larger pulse. There was

no noticeable difference in performance between low-high and high-low contrast sequences.

Both the direction identification and the simple contrast-detection probabilities can be

represented by the same psychometric function of the luminance increment Delta L, provided

that Delta L is normalized by the nth power of the background luminance level, L(b). These

results suggest that the general Reichardt-type scheme of movement encoding should be

modified in the manner proposed for the fly's visual system [5. Opt. Sec, Am. A 6, 116

(1989)]: (1) the mean luminance is subtracted from the input signal before the signal is

subjected to a nonlinear compression and (2) saturation characteristics are inserted into both

branches of the two mirror-symmetric motion-detection subunits before multiplication of the

input signals. The identical metric of the contrast response suggests that movement

discrimination and luminance detection are two different special-purpose computations

performed on the output of the same encoding network.



Allik, J. and A. Pulver (1995). “Magnitude of Luminance Modulation Specifies Amplitude of

Perceived Movement.” Perception & Psychophysics 57(1): 27-34.

A compelling impression of movement, which is perceptually indistinguishable from a real

displacement, can be elicited by patterns containing no spatially displaced elements. An

apparent oscillation, w-movement, was generated by a stationary pattern containing a large

number of horizontal pairs of spatially adjacent dots modulated in brightness. The observer's

task was to adjust the perceived amplitude of the w-motion to match the amplitude of a real

oscillation. All of the data can be accounted for by a simple rule: If the relative change in the

luminance, W = Delta L/L, between two adjacent stationary dots is kept constant, the distance

over which these dots appeared to travel in space comprises a fixed fraction of the total

distance by which they are separated. The apparent amplitude of the w-motion increases

strictly in proportion with luminance contrast, provided that the contrast is represented in the

motion-encoding system by a rapidly saturating compressive Weibull transformation. These

findings can be explained in terms of bilocal motion encoders comparing two luminance

modulations occurring at two different locations.



Allik, J., T. Tuulmets, et al. (1991). “Size invariance in visual number discrimination.” Psychological

Research/Psychologische Forschung 53(4): 290-295.

Examined the observer's ability to discriminate the numerosity of 2 random dot-patterns

irrespective of their relative size. Pattern 1 was composed of 32 dots randomly distributed

within an invisible square window, and Pattern 2 was the test pattern with 1 of 5

magnifications where the relative number of dots varied on 11 levels. The observer's task was

to indicate which of the 2 patterns contained more dots. Results show that the stimulus size, as

an irrelevant stimulus attribute, could be ignored in the judgments about relative numerosity.

The perceived numerosity was size invariant, at least for 1.6-times magnification and a 3-

times reduction of the test pattern. The size invariance observed constrained the range of

potential models, since the perceived numerosity could be identified only by a feature of the

stimulus that would remain invariant after any change in the absolute stimulus size.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 524 of 887 in

PsycINFO 1990-1992



Allison, R. S. and I. P. Howard (2000). “Stereopsis with persisting and dynamic textures.” Vision

Research 40(28): 3823-3827.

We measured the percept of changing depth from changing disparity in stereograms composed

of random-dot textures that were either persistent or dynamically changed on every frame (a

dynamic random-dot stereogram). Disparity was changed between frames to depict a surface

undergoing smooth temporal changes in simulated slant. Matched depth was greater with

dynamic random-dot stereograms than with persistent random-dot stereograms. These results

confirm and extend earlier observations at depth threshold. We posit an explanation based on

cue conflict between stereopsis and monocular depth cues. (C) 2000 Elsevier Science Ltd. All

rights reserved.



Alliston, E. L., M. S. Friehling, et al. (2001). “Detectability of global form in glass patterns and random

dot motion stimuli depends only on signal-to-noise ratio.” Investigative Ophthalmology &

Visual Science 42(4): S872-S872.



Altenmueller, E., R. Jung, et al. (1989). “Premotor programming and cortical processing in the cerebral

cortex: Electrophysiological correlates of hemispheric dominance.” Brain, Behavior and

Evolution 33(2-3): 141-146.

Slow brain potentials were averaged from 12-25 EEG records before and during voluntary

hand movements and writing, spatial vision, language, and calculation tasks without

vocalization and with visual fixation. The electrooculogram (EOG) and writing pressure or

electromyogram (EMG) were recorded simultaneously. Skilled actions caused largest negative

potentials in the contralateral sensorimotor hand area. Left-sided lateralization or bilaterally

equal surface-negative potential shifts appeared during language and calculation tasks in 90%

of the right-handers and in 75% of the left-handers. Right-sided lateralizations occurred during

the viewing of perspective Necker figures or random-dot stereograms in the large majority of

all Ss tested. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 591 of

887 in PsycINFO 1988-1989



Amidror, I. (2003). “Glass patterns as moire effects: new surprising results.” Optics Letters 28(1): 7-9.

It is well known that the superposition of two identical random dot patterns may give rise to a

particular form of moire effect known as a Glass pattern. Surprisingly, new research results

show that if one chooses appropriate dot shapes for each of the two random dot patterns, while

keeping the random dot locations in both layers identical, it is possible to synthesize in the

superposition a Glass pattern having any desired shape and intensity profile. (C) 2003 Optical

Society of America.

Amidror, I. (2003). “Moire patterns between aperiodic layers: quantitative analysis and synthesis.”

Journal of the Optical Society of America a-Optics Image Science and Vision 20(10): 1900-

1919.

Moire effects that occur in the superposition of aperiodic layers such as random dot screens

are known as Glass patterns. Unlike classical moire effects between periodic layers, which are

periodically repeated throughout the superposition, a Glass pattern is concentrated around a

certain point in the superposition, and farther away from this point it fades out and disappears.

I show that Glass patterns between aperiodic layers can be analyzed by using an extension of

the Fourier-based theory that governs the classical moire patterns between periodic layers.

Surprisingly, even spectral-domain considerations can be extended in a natural way to

aperiodic cases, with some straightforward adaptations. These new results allow us to predict

quantitatively the intensity profile of Glass patterns; furthermore, they open the way to the

synthesis of Glass patterns that have any desired shapes and intensity profiles. (C) 2003

Optical Society of America.



Anastasopoulos, D., K. Bhatia, et al. (1997). “Perception of spatial orientation in spasmodic torticollis

.2. The visual vertical.” Movement Disorders 12(5): 709-714.

Twenty-nine patients with idiopathic spasmodic torticollis (ST) and matched normal control

subjects were asked to align a target line to perceived earth vertical [visual vertical (VV)].

Settings were made against a whole-field random-dot background that was either stationary or

rotating around the line of sight, and subjects performed the task upright and lying

horizontally on their sides. Normal subjects were tested both head upright and after assuming

a voluntary head tilt. Patients with ST set the VV close to true upright with a minimal

deviation toward tilt of the head in contrast to normal subjects assuming a head tilt who set the

VV in the opposite direction to the head tilt (Muller ''E'' effect). Settings against the spinning

disk were biased in the direction of rotation similarly for both subject groups. Settings made

against static or spinning disk performed when subjects lay horizontally were tilted in the

direction of recumbence (Aubert ''A'' effect) similarly for both subject groups. When

attempting to set the target line parallel to the long axis of the face, patients with head tilt set

the line to upright, whereas normal subjects correctly estimated their tilts. One hypothesis

offered to explain these results is that the patients referenced only their upright trunk for

vertical and did not make use of neck proprioceptive or vestibular signals of head tilt so that

all settings were made as if the trunk and head were upright. Alternatively, patients may have

used only otolith signals as the reference for upright, and these are recalibrated in ST patients

with head tilt. The pathological deviation becomes accepted as upright posture, and VVs and

facial orientation are estimated as if the head were upright. In either case the findings indicate

abnormal processing of the perception of visual verticality in ST patients.



Andersen, G. J. (1990). “Focused attention in three-dimensional space.” Perception and Psychophysics

47(2): 112-120.

Assessed the size of focused attention within a 3 dimensional (3-D) display. In 2 experiments,

a total of 28 undergraduates viewed random-dot stereogram displays in which they responded

differentially to vertical and horizontal bars. Adjacent noise elements either were identical to

the response target or specified the opposite response. The position of the noise elements was

varied in depth according to binocular disparity. Interference by incompatible noise elements

decreased with depth separation between the noise elements and response target. Interference

was greater for noise elements that were more distant from the observer than from the

response target than it was for noise elements that were closer to the observer than to the

response target. Results support the hypothesis that focused attention is restricted to a limited

region in 3-D space. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record

570 of 887 in PsycINFO 1990-1992



Anderson, B. L. (1992). “Hysteresis, Cooperativity, and Depth Averaging in Dynamic Random-Dot

Stereograms.” Perception & Psychophysics 51(6): 511-528.

Experiments were performed to assess the response of the human visual system to dynamic

random-dot patterns composed of disparity mixtures. In Experiment 1, the perceived depth

and relative stability of two patterns were compared; one pattern depicted two transparent

layers of dots, and the other depicted a volume of dots. Two effects were found: (1) the

volume pattern exhibited a large degree of disparity averaging; and (2) asymmetries were

observed in the relative stability of these two patterns. Experiment 2 was designed to

determine whether these findings could be attributed to spatially localized processes occurring

at the location of disparity discontinuities. This was accomplished by introducing unpaired

noise points localized either along the disparity discontinuities or in the center of the layered

and volume patterns. The amount of depth averaging and the direction of the asymmetry did

not appear to depend on processes localized along the disparity discontinuities. Results of

these experiments, taken in conjunction with those of previous studies, suggest that hysteresis

is independent of cooperative persistence mechanisms.



Anderson, B. L. and K. Nakayama (1994). “Toward a General-Theory of Stereopsis - Binocular

Matching, Occluding Contours, and Fusion.” Psychological Review 101(3): 414-445.

Models of stereopsis have focused on developing strategies for identifying common features

in the 2 half-images so that disparity may be computed. This emphasis ignores the unpairable

features that arise at occluding contours (half-occlusions). Most models treat half-occlusions

as noise or outliers that are interpreted after disparity processing is completed. A series of

experiments reveal that occlusion relationships are sensed during the earliest stages of

binocular processing. The authors hypothesize the existence of receptive field structures that

sense the local structure of stereoscopic occlusion relationships to account for these findings.

Finally, a simple theoretical framework is presented in which fusion, stereopsis, and occlusion

are unified. This theory explains the co-occurrence of stereopsis and diplopia and how half-

occlusions escape the suppression characteristic of binocular rivalry.



Anderson, K. C. and R. M. Siegel (1999). “Optic flow selectivity in the anterior superior temporal

polysensory area, STPa, of the behaving monkey.” Journal of Neuroscience 19(7): 2681-2692.

Earlier studies of neurons in the anterior region of the superior temporal polysensory area

(STPa) have demonstrated selectivity for visual motion using stimuli contaminated by

nonmotion cues, including texture, luminance, and form. The present experiments investigated

the motion selectivity of neurons in STPa in the absence of form cues using random dot optic

flow displays. The responses of neurons were tested with translation, rotation. radial, and

spiral optic flow displays designed to mimic the types of motion that occur during locomotion.

Over half of the neurons tested responded significantly to at least one of these displays. On a

cell by cell basis, 60% of the neurons tested responded selectively to rotation, radial, and

spiral motion, whereas 20% responded selectively to translation motion. The majority of

neurons responded maximally to single-component optic flow displays but was also

significantly activated by the spiral displays that contained their preferred component.

Moreover, there was a bias in the selectivity of the neurons for radial expansion motion. These

results suggest that neurons within STPa are contributing to the analysis of optic flow.

Furthermore, the preponderance of cells selective for radial expansion provides evidence that

this area may be specifically involved in the processing of forward locomotion and/or looming

stimuli. Finally, these results provide carefully controlled physiological evidence for an

extension and specialization of the motion-processing pathway into the anterior temporal lobe.



Anooshian, L. J. (1997). “Distinctions between implicit and explicit memory: Significance for

understanding cognitive development.” International Journal of Behavioral Development

21(3): 453-478.

This research was designed to explore developmental trends for implicit and explicit memory

as well as relations between memory measures and other aspects of cognitive development for

preschool and second-grade children, and adults. For one task, children and adults gradually

clarified patterns of random dots until they could identify an emerging picture, in each of two

testing sessions separated by one week. Reliable effects for testing session and age group were

obtained for explicit memory (verbal recall as well as frequency and recognition ratings), but

not for implicit memory. Typicality ratings, also obtained in this picture-clarification task,

appeared more related to implicit than explicit memory. For other tasks, children and adults

completed word stems (e.g. BR---) and provided examples of categories (e,g. animals), The

absence of developmental differences for implicit memory contrasted with clear

developmental improvement for recall (explicit memory). Other tasks-perceptual

classification, and, for younger children, assessments of theories of mind-provided other

measures of cognitive development. Measures of perceptual classification were generally

unrelated to implicit or explicit memory; for preschoolers with poor explicit memory, naive

theories of mind were associated with good implicit memory. Results were discussed

primarily in terms of the significance of both implicit and explicit memory for understanding

diverse areas of cognitive development.



Anson, L. F. (1993). Fractal Image Compression. Byte: 192-202.



Anstis, S. (1986). “Visual stimuli on the Commodore Amiga: A tutorial.” Behavior Research Methods,

Instruments and Computers 18(6): 535-541.

Describes how to produce some commonly desired visual stimuli on the Commodore Amiga

microcomputer using the DeLuxePaint software package. These include random-dot

stereograms, apparent motion, texture edges, aftereffects from dimming and brightening,

dynamic random noise, and drifting and counterphase gratings. (PsycINFO Database Record

(c) 2002 APA, all rights reserved) Record 638 of 887 in PsycINFO 1985-1987



Anstis, S. (1998). “Picturing peripheral acuity.” Perception 27(7): 817-825.

The grain of the retina becomes progressively coarser from the fovea to the periphery. This is

caused by the decreasing number of retinal receptive fields and decreasing amount of cortex

devoted to each degree of visual field (= cortical magnification factor) as one goes into the

periphery. We simulate this with a picture that is progressively blurred towards its edges;

when strictly fixated at its centre it looks equally sharp all over.



Anstis, S. M. (1970). “Phi movement as a subtraction process.” Vision Research 10: 1411-1430.

How similar must two succesively presented objects be for phi movement to be perceived

between them? Conclusions: Phi movement was perceived between nearby points of similar

brightness, irrespective of form or colour. Phi like stereopsis depended on point-by-point

comparison of brightness between two patterns.



Anzai, A., I. Ohzawa, et al. (1999). “Neural mechanisms for processing binocular information I. Simple

cells.” Journal of Neurophysiology 82(2): 891-908.

The visual system integrates information from the left and right eyes and constructs a visual

world that is perceived as single and three dimensional. To understand neural mechanisms

underlying this process, it is important to learn about how signals from the two eyes interact at

the level of single neurons. Using a sophisticated receptive field (RF) mapping technique that

employs binary m-sequences, we have determined the rules of binocular interactions exhibited

by simple cells in the cat's striate cortex in relation to the structure of their monocular RFs. We

find that binocular interaction RFs of most simple cells are well described as the product of

left and right eye RFs. Therefore the binocular interactions depend not only on binocular

disparity but also on monocular stimulus position or phase. The binocular interaction RF is

consistent with that predicted by a model of a linear binocular filter followed by a static

nonlinearity. The static nonlinearity is shown to have a shape of a half-power function with an

average exponent of similar to 2. Although the initial binocular convergence of signals is

linear, the static nonlinearity makes binocular interaction multiplicative at the output of simple

cells. This multiplicative binocular interaction is a key ingredient for the computation of

interocular cross-correlation, an algorithm for solving the stereo correspondence problem.

Therefore simple cells may perform initial computations necessary to solve this problem.



Arakawa, K., S. Tobimatsu, et al. (1999). “Parvocellular and magnocellular visual processing in

spinocerebellar degeneration and Parkinson's disease: an event-related potential study.”

Clinical Neurophysiology 110(6): 1048-1057.

Objective: We recorded event-related potentials (ERPs) using appropriate visual stimuli to

establish a non-invasive method that separately investigates the parvocellular (P) and

magnocellular (M) visual functions, and to evaluate the visual function in spinocerebellar

degeneration (SCD) and Parkinson's disease (PD).Methods: Eight SCD and 10 PD patients

were compared with 11 age-matched control subjects. In the P-task, subjects were required to

discriminate equiluminant red (frequent) and green (rare) random dots. In the M-task, moving

random dots on a rotating cylinder (frequent) and those moving irregularly (rare) were

discriminated.Results: Control subjects showed an endogenous positive component at 400 ms

(P400(p)) with an early exogenous negative potential (N160(p)) in the P-task. In the M-task,

N160(m) and P400(m) were recorded. A deuteranope lacked P400(p) with normal P400(m). In

SCD, P400(p) latency and N160(p)-P400(p) interval were increased with normal N160(p)

latency. N160(m) latency was also increased while N160(m)-P400(m) interval was normal. In

PD, there were no significant changes in the P-task but P400(m) latency was increased with

normal N160(m) latency.Conclusions: SCD patients may have not only abnormal higher

processing in the P-pathway but abnormal fundamental processing in the M-pathway. PD may

have impaired higher processing of the M-pathway with the preserved P-function. (C) 1999

Elsevier Science Ireland Ltd. All rights reserved.



Arakawa, K., S. Tobimatsu, et al. (1999). “Parvocellular and magnocellular visual processing in

spinocerebellar degeneration and Parkinson's disease: An event-related potential study.”

Clinical Neurophysiology 110(6): 1048-1057.

Recorded event-related potentials (ERPs) using appropriate visual stimuli to establish a non-

invasive method that separately investigates the parvocellular (P) and magnocellular (M)

visual functions, and to evaluate the visual function in spinocerebellar degeneration (SCD) and

Parkinson's disease (PD). Eight SCD and 10 PD patients aged 51-65 yrs were compared with

11 age-matched controls Ss. In the P-task, Ss were required to discriminate equiluminant red

(frequent) and green (rare) random dots. In the M-task, moving random dots on a rotating

cylinder (frequent) and those moving irregularly (rare) were discriminated. Control Ss showed

an endogenous positive component at 400 msec with an early exogenous negative potential in

the P-task. In SCD, latency and interval were increased with normal latency. In PD, there were

no significant changes in the P-task, but latency was increased with normal latency. SCD

patients may have not only abnormal higher processing in the P-pathway but abnormal

fundamental processing in the M-pathway. PD may have impaired higher processing of the M-

pathway with the preserved P-function. (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 193 of 887 in PsycINFO 1999



Archer, S. M., K. K. Miller, et al. (1986). “Vergence Amplitudes with Random-Dot Stereograms.”

British Journal of Ophthalmology 70(10): 718-723.



Arnold, P. (1978). “Mental rotation by deaf and hearing children.” Perceptual and Motor Skills 47(3, Pt

1): 977-978.

26 profoundly deaf children were shown to be superior to 33 hearing children in their ability

to rotate mental images of random dots in matrices. This suggests that their poor linguistic

skills may be augmented by the use of visual imagery in certain situations. (6 ref) (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 797 of 887 in PsycINFO 1978-

1984



Arnott, S. R. and J. M. Shedden (2000). “Attention switching in depth using random-dot

autostereograms: Attention gradient asymmetrics.” Perception and Psychophysics 62(7):

1459-1473.

Random-dot autostereograms (RDASs) were used to investigate attention shifts along the

sagittal plane in distractor-free tasks of high perceptual load. In three experiments using a

same/different comparison task, the shape of the gradient over five different depths was

examined and the conditions under which the gradient is and is not observed were compared.

16 Ss participated in at least one of the experiments. Results found that when the target set

consisted of five similar objects, a robust asymmetric depth gradient was observed. When the

target set consisted of two dissimilar objects, no gradient was observed. It is concluded that

the results support a hypothesis of a viewer-centered asymmetric attention gradient in the

depth plane that is dependent on perceptual or attentional load. (PsycINFO Database Record

(c) 2002 APA, all rights reserved) Record 142 of 887 in PsycINFO 2000



Arnott, S. R. and J. M. Shedden (2000). “Attention switching in depth using random-dot

autostereograms: Attention gradient asymmetries.” Perception & Psychophysics 62(7): 1459-

1473.

Random-dot autostereograms (RDASs) were used to investigate attention shifts along the

sagittal plane in distractor;free tasks of high perceptual load. In three experiments using a

same/different comparison task, the shape of the gradient over five different depths was

examined and the conditions under which the gradient is and is not observed were compared.

When the target set consisted of five similar objects, a robust asymmetric depth gradient was

observed. When the target set consisted of two dissimilar objects, no gradient was observed.

The results support a hypothesis of a viewer-centered asymmetric attention gradient in the

depth plane that is dependent on perceptual or attentional load defined by target-set

discriminability.



Arterberry, M. E. (1992). “Infants Perception of 3-Dimensional Shape Specified by Motion-Carried

Information.” Bulletin of the Psychonomic Society 30(4): 337-339.

The purpose of this study was to replicate Arterberry and Yonas (1988) with an added control

group to provide further evidence that infants respond to distal shape specified by motion-

carried information. In a habituation procedure, 4-month-old infants were tested for

discrimination of a complete and incomplete cube specified in computer-generated, kinetic

random-dot displays. Two groups of infants were tested. One group was provided with a full

view of the habituation and test displays (called the full-view group). A second group of

infants viewed only the central region in which differential motion was located (called the

partial-view group). The full-view group provided evidence of discriminating the two objects,

whereas the partial-view group did not. These findings suggest that 4-month-old infants do

perceive three-dimensional shape specified by motion-carried information.



Arterberry, M. E. (1992). “Infants' perception of three-dimensional shape specified by motion-carried

information.” Bulletin of the Psychonomic Society 30(4): 337-339.

Replicated the study of M. E. Arterberry and A. Yonas (1988) with an added control group to

provide further evidence that infants respond to distal shape specified by motion-carried

information. In a habituation procedure, 24 4-mo-old infants were tested for discrimination of

a complete and incomplete cube specified in computer-generated, kinetic random dot displays.

Two groups of Ss were tested (i.e., a full-view group and a partial-view group). The full-view

group discriminated the 2 objects, whereas the partial-view group did not. Findings suggest

that 4-mo-old infants do perceive 3-dimensional shape specified by motion-carried

information. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 507 of

887 in PsycINFO 1990-1992



Arterberry, M. E. and A. Yonas (1988). “Infants' sensitivity to kinetic information for three-

dimensional object shape.” Perception and Psychophysics 44(1): 1-6.

Investigated infant sensitivity to kinetic information specifying 3-dimensional object shape

using computer-generated random-dot displays. 24 4 mo-old infants were habituated to

displays of an object oscillating about 2 different axes on alternating trials. Following

habituation, the Ss were tested for recovery from habituation to a display of the same object

and a novel object. Both test displays employed a new axis of rotation. The Ss generalized

habituation to same object and increased their looking to the new object. Results provide

evidence that infants are sensitive to motion-carried information specifying 3-dimensional

object shape, since the random-dot displays minimized static information that differentiated

the 2 objects. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 611 of

887 in PsycINFO 1988-1989



Arterberry, M. E. and A. Yonas (2000). “Perception of three-dimensional shape specified by optic flow

by 8-week-old infants.” Perception & Psychophysics 62(3): 550-556.

Sensitivity of 8-week-old infants to optical flow specifying the shape of a three-dimensional

object was assessed. Infants viewed kinetic random-dot displays that specified three-

dimensional cubes. The cubes were identical except for the presence or absence of an interior

corner. Half of the infants viewed the full display. The other half viewed the central region of

the displays, where the flow specifying the presence or absence of the corner differed. Infants

in the full-view condition looked significantly longer to a novel cube than to the familiar cube

following habituation. In contrast, infants in the partial-view condition looked equally to the

novel and familiar cubes, ruling out the possibility that infants who viewed the full displays

merely discriminated differences in motion in the central region of the two displays. These

findings suggest that infants as young as 8 Reeks perceive three-dimensional object shape

from optic flow.



Atkins, G. (1990). “Random-Dot Hologram.” Optics Letters 15(23): 1392-1393.



Atkinson, J. and O. Braddick (1976). “Stereoscopic discrimination in infants.” Perception 5(1): 29-38.

Investigated the ability to make discriminations of binocular disparity in 4 2-mo-old infants by

2 methods: (a) fixation preference between patterns differing in the disparity they contained

and (b) recovery from habituation of high-amplitude sucking when there was a change in

disparity in the visual reinforcer. The stimuli were random-dot stereograms. Results of both

methods indicate that at least some infants of this age can perform stereoscopic

discriminations and that both techniques are feasible for development for longitudinal studies

of stereoscopic vision. (20 ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 829 of 887 in PsycINFO 1967-1977



Attneave, F. (1959). “Stochastic Composition Processes.” The Journal of Aesthetics and Art Criticism

17(4): 503-510.

By stochastic composition processes one can arrive at visual designs similar to those seen in

primitive basketry. It is held that the use of these processes can lead not only to a new art work

in the style of some artist but that new styles may eventually be created.



Attneave, F. and M. D. Arnoult (1956). “The quantitative study of shape and pattern perception.”

Psychological Bulletin 53: 452-471.

There is a need to extend the traditional psycho-physical methods to include the analysis of

shapes or patterns. Heretofore studies designed to determine how form perception is

influenced by various extrinsic factors have employed arbitrarily designed stimuli. This paper

proposes several methods "for drawing 'random' patterns and shapes from clearly defined

hypothetical populations, to which experimental results may then be generalized with

measurable confidence."



Aznar, J. A. and J. Bayo (1993). “Prediccion del valor motor ocular y la profundidad subjetiva en

estereopsis visual. / Prediction of ocular motor value and subjective depth in visual

stereopsis.” Anuario de Psicologia 58(3): 3-25.

Studied the possibility of obtaining a linear adjustment of the function defined by indicators of

motor value determined by relative geometric coordinates, the possibility of obtaining a

function that permits estimation of subjective space based on binocular disparity, and the

possibility of obtaining an equation to be used in estimating subjective space using ocular

motor value. Ss were 10 undergraduate students. A geometric optical method and a direct

psychophysical method using the random-dot stereogram were used. (English abstract)

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 442 of 887 in

PsycINFO 1993-1995



Azzopardi, P. and A. Cowey (2001). “Motion discrimination in cortically blind patients.” Brain 124:

30-46.

Some patients with brain damage affecting the striate cortex, though clinically blind in their

field defects, can still discriminate visual stimuli when forced choice procedures are used.

Such patients seem particularly sensitive to moving stimuli in their scotomata, though there

are conflicting reports as to whether they can discriminate the direction of motion, We tested

three patients with areas of cortical blindness for their ability to detect and discriminate the

direction of motion of a variety of first-order motion stimuli, namely bars, gratings, plaids and

random dot kinematograms depicting translation and motion in depth, during forced choice

tasks. The patients could detect the presence of movement in any kind of stimulus, and could

discriminate the direction of single bars, but none could discriminate the direction of motion

of the more complex stimuli (gratings, plaids and random dot kinematograms) or discriminate

between 0 and 100% coherent random dot kinematograms at any speed tested (from 4 to 640

degrees /s). Similar results were obtained from one of the patients who was additionally tested

with second order versions of the translated bar and random dot kinematograms, eliminating

light scatter as an explanation. Overall, the results suggest that motion processing in the

scotoma is severely impaired, and that the puzzling discrepancies between previous studies

can be accounted for by the type of stimulus used. The motion discrimination impairment

caused by brain damage affecting the primary visual cortex is inconsistent with the proposed

existence of a subcortical pathway to extrastriate cortical motion areas (such as areas MT and

MST) which bypasses the striate cortex and is specialized for analysing 'fast' motion.



Azzopardi, P., M. Fallah, et al. (2003). “Response latencies of neurons in visual areas MT and MST of

monkeys with striate cortex lesions.” Neuropsychologia 41(13): 1738-1756.

Cortical area, MT (middle temporal area) is specialized for the visual analysis of stimulus

motion in the brain. It has been suggested [Brain 118 (1995) 1375] that motion signals reach

area MT via two dissociable routes, namely a 'direct' route which bypasses primary visual

cortex (area, striate cortex (V1)) and is specialized for processing 'fast' motion (defined as

faster than 6degrees/s) with a relatively short latency, and an 'indirect' route via area V1 for

processing 'slow' motion (slower than 6degrees/s) with a relatively long latency. We tested this

proposal by measuring the effects of unilateral V1 lesions on the magnitudes and latencies of

responses to fast- and slow-motion (depicted by random dot kinematograms (RDK)) of single

neurons in areas MT and medial superior temporal area (MST) of anaesthetized macaque

monkeys. In the unlesioned hemisphere contralateral to a VI lesion, response. magnitudes and

latencies of MT neurons were similar to those previously reported from MT neurons in normal

monkeys, and there was no significant association between slow movement and long response

latency (>100 ms), or between fast movement and short latency (less than or equal to 100 ms).

VI lesions led to diminished response magnitudes and increased latencies in area MT of the

lesioned hemisphere, but did not selectively abolish MT responses to slow moving stimuli, or

abolish long-latency responses to either slow- or fast-moving stimuli. Response magnitudes

and latencies in area MST, which receives visual inputs directly from area MT and is also

specialized for visual analysis of motion, were unaffected by VI lesions (though we have

shown elsewhere that directionally-selective responses in both areas were impaired by VI

lesions). Overall, the results are incompatible with the hypothesis that there are dissociable

routes to MT specialized for processing separately fast and slow motion. (C) 2003 Published

by Elsevier Ltd.



Bacon, B. A., F. Lepore, et al. (2000). “Neurons in the posteromedial lateral suprasylvian area of the

cat are sensitive to binocular positional depth cues.” Experimental Brain Research 134(4):

464-476.

Single units in the posteromedial lateral suprasylvian area of the cat are known to be very

sensitive to movement. A proportion of these cells can encode movement in depth, but it is

unclear whether posteromedial lateral suprasylvian cells only rely upon motion cues to

evaluate stimulus depth or whether they can also code for spatial cues. The present study aims

at assessing the sensitivity to spatial disparity of binocular cells, in the postero-medial lateral

suprasylvian area, in order to determine whether these units are tuned to positional depth cues.

A total of 126 single cells located in the posteromedial lateral suprasylvian area of

anesthetized, paralyzed cats were examined. As recordings were performed in the central

visual field representation, receptive fields were small. A third of the receptive fields were

surrounded by an inhibitory region and almost three-quarters of the cells were direction-

selective. Most cells (110/114) were binocular, and a large proportion of single neurons

responded to stimuli appearing on the fixation plane by increasing (tuned excitatory cells,

43%) or decreasing (tuned inhibitory cells, 14%) their response rate. A smaller proportion of

cells increased their firing rate in response to crossed (near cells, 10%) or uncrossed (far cells,

6%) spatial disparities, hence demonstrating respective preference for stimuli presumably

appearing in front of or behind the fixation plane. As compared to primary visual cortex, the

proportion of disparity-sensitive cells in posteromedial lateral suprasylvian area is similar, but

selectivity is significantly coarser. As the posteromedial lateral suprasylvian area can code for

both spatial and temporal aspects of stimuli, this area might be involved in the spatiotemporal

integration of depth cues, a process that may also participate in the control of accommodation

and vergence.



Bacon, B. A., J. Villemagne, et al. (1998). “Spatial disparity coding in the superior colliculus of the

cat.” Experimental Brain Research 119(3): 333-344.

Cells in the superficial layers of the superior colliculus of the cat have mainly binocular

receptive fields. The aim of the present experiment was to investigate the sensitivity of these

cells to horizontal spatial disparity. Unit recordings were carried out in the superficial layers of

the superior colliculus of paralyzed and anesthetized cats, Centrally located receptive fields

were mapped, separated using prisms, and then stimulated simultaneously using two luminous

bars optimally adjusted to the size of the excitatory region of the receptive fields. Only

binocular cells were tested, and 65% of these units were found to be sensitive to spatial

disparities. Some cells (20%) were clearly insensitive to spatial disparity and the remaining

15% showed complex, unclassifiable interactions. The sensitive cells could be divided into

four classes based on their disparity-sensitivity profiles: 38% showed excitatory interactions,

whereas 9% showed inhibitory interactions. Moreover, 11% and 7% of the cells responded,

respectively, to crossed or uncrossed disparities, and were classified as near cells and far cells.

Whereas the general shapes of the sensitivity profiles were similar to those of cells in areas

17-18, selectivity in the superior colliculus was significantly coarser. The superficial layers of

the superior colliculus project topographically to the deep layers of the superior colliculus,

which are known to contain circuits involved in the control of ocular movements. The results

thus suggest that disparity-sensitive cells of the superior colliculus could feed information to

these oculomotor neurons, allowing for the localization and fixation of objects on the

appropriate plane of vision.



Baddeley, A. and R. D. Gill (1993). Kaplan-Meier estimators for interpoint distance distributions of

spatial point processes. Amsterdam, Department of Operations Research, Statistics, and

Systems Theory.



Baker, C. L. and O. J. Braddick (1982). “The Basis of Area and Dot Number Effects in Random Dot

Motion Perception.” Vision Research 22(10): 1253-1259.



Baker, C. L. and O. J. Braddick (1982). “Does segregation of differently moving areas depend on

relative or absolute displacement?” Vision Research 22(7): 851-856.

Examined the occurrence of segregation in random dot kinematograms in which a central

patch of dots and the surrounding area were each coherently displaced, either in the same or

opposite directions by varying amounts. One of the authors and an experimentally naive S

served as observers. The limiting displacement for segregation to occur was determined

primarily by the displacement of each region alone rather than the relative displacement of

neighboring regions. It is concluded that the "correspondence problem" is solved by a short

range motion detection process acting on each region separately: segregation is achieved by

comparing the results of this process for adjacent regions. (27 ref) (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 740 of 887 in PsycINFO 1978-1984



Baker, C. L. and O. J. Braddick (1985). “Eccentricity-dependent scaling of the limits for short-range

apparent motion perception.” Vision Research 25(6): 803-812.

Examined the phenomenon in which the ability to report the direction of apparent motion

when an array of random dots is displaced fails when the displacement exceeds a limiting

value (d-sub(max)), using 1 naive observer and 4 experienced observers (including the 2

authors). It was found that d-sub(max ) increased rapidly with retinal eccentricity, in a manner

different from spatial measures such as acuity that are believed to depend on the magnification

factor of projection to Area 17. The minimum displacement giving detectable motion (d-

sub(min)) showed a shallower increase with eccentricity that was more compatible with the

variation of cortical magnification. The dependence of apparent motion on the timing

variables (exposure duration, interstimulus interval) changed negligibly with eccentricity.

Consequently, the dynamic range and the upper limit of detectable velocities increased greatly

with eccentricity. Results indicate that the increase of d-sub(max ) with eccentricity means

that the perception of apparent motion will show an approximate invariance with display

scale, even though d-sub(max ) has a locally fixed value depending on receptive field

structure. (46 ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 673

of 887 in PsycINFO 1985-1987



Baker, C. L. and O. J. Braddick (1985). “Temporal properties of the short-range process in apparent

motion.” Perception 14(2): 181-192.

Examined the perception of random-dot 2-frame apparent motion in which the durations of

each exposure and the interstimulus interval between them were varied. The authors and 1

naive observer served as Ss. Results are consistent with the rule that, for optimal motion

detection, a portion of each exposure must fall within the same time interval of about 40 msec.

Results show that motion perception is separably dependent on the displacement from one

exposure to the next and on the time interval between those exposures, rather than on the

velocity implied by their ratio. (30 ref) (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 665 of 887 in PsycINFO 1985-1987



Baker, C. L. and R. F. Hess (1998). “Two mechanisms underlie processing of stochastic motion

stimuli.” Vision Research 38(9): 1211-1222.

We have constructed "limited lifetime" stochastic motion stimuli using Gabor functions

instead of dots, thereby controlling the local attributes of spatial frequency and orientation.

Human psychophysical data for direction discrimination using these stimuli reveal two

qualitatively distinct kinds of processing. For small displacements, direction discrimination

performance as a function of displacement is scaled with spatial frequency in a manner

consistent,vith a linear filtering motion mechanism. Motion perception for relatively large

displacements is not directly related to the spatial frequency, and is consistent with a nonlinear

process which signals motion of contrast envelopes. (C) 1998 Elsevier Science Ltd. All rights

reserved.



Baker, C. L., R. F. Hess, et al. (1991). “Residual Motion Perception in a Motion-Blind Patient,

Assessed with Limited-Lifetime Random Dot Stimuli.” Journal of Neuroscience 11(2): 454-

461.

A neurological patient (L.M.) suffering a specific loss of visual motion perception (Zihl et al.,

1983) due to extrastriate cortical damage was studied using random dot "limited-lifetime"

stimuli with a direction discrimination task. With a stimulus like that of Newsome and Pare

(1988), the patient exhibited a severe deficit for motion perception, only being able to perform

well for very high values of coherence.Different versions of the stimulus were employed to

separate out the effects of limited lifetime versus the effects of additive noise as coherence

was lowered. When all "signal" dots had a fixed, specified value of lifetime, and varying

percentages of "noise" dots were added, the patient showed a profound deficit. In contrast, a

stimulus consisting of no noise dots at all, and signal dots having fixed values of lifetime,

revealed relatively good performance for surprisingly brief dot lifetimes. Thus, it is the

presence of noisy, incoherent dot motion, rather than brief lifetimes, that causes such poor

performance on the stimulus of Newsome and Pare (1988). Most surprising was the finding

that the presence of even very small percentages of stationary noise dots was sufficient to

disrupt totally direction discrimination of moving signal dots.The findings reported here

suggest that one major role of extrastriate cortical processing might be the interpretation of

stimuli that suffer from an impaired signal-to-noise ratio; the most commonly encountered

form of "noise" would presumably be contamination by irrelevant directional spatiotemporal

frequency components.



Baker, R. and et al. (1983). “Effects of atropine on visual performance.” Military Medicine 148(6):

530-535.

Two experiments compared atropine (2 mg/70 kg) to a placebo on some basic visual functions

and on 2 more complex visual-motor performance tasks. 16 males 20-23 yrs old served as Ss.

Atropine elevated pulse rates, and Ss reported moderate dry mouth and intoxication, but these

effects subsided within 4 hrs of injection. Atropine reduced lens accommodation 16%,

increased pupil area 50%, and reduced contrast sensitivity slightly at all spatial frequencies 4

hrs after injection. Accommodative and pupil dynamics, visual acuity, intraocular pressure,

saccadic eye movements, depth perception, and color vision were not significantly affected.

Exp II consisted of 2 complex tasks: In the 1st, 6 21-32 yr old males repeatedly focused on

targets at 2 distances, and target identification RTs were measured. The 2nd task required Ss

to search for and identify the location of a target in random dot patterns, while suppressing

vestibular eye movements induced by a rotation in a servo-controlled chair. Ss performed both

tasks as rapidly and accurately after atropine as after placebo. It would appear that in

controlled laboratory conditions, a 2-mg dose of atropine can affect near vision but will not

impair general performance in males under the age of 35 yrs. (9 ref) (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 722 of 887 in PsycINFO 1978-1984



Balaban, C. D. and M. Ariel (1992). “A Beat-to-Beat Interval Generator for Optokinetic Nystagmus.”

Biological Cybernetics 66(3): 203-216.

An analysis of optokinetic responses was used to derive an iterative model that reproduces the

duration of nystagmus slow phases and eye position control during optokinetic nystagmus.

Optokinetic nystagmus was recorded with magnetic search coils from red-eared turtles

(Pseudemys scripta elegans) during monocular, random dot pattern stimulation at constant

velocities ranging from 0.25-63-degrees/s. The beat-to-beat behavior of slow phase durations

was consistent with the existence of an underlying neural clock, termed the basic interval

generator, that is based on an integrate-to-fire neuron model. This hypothetical basic interval

generator produces an interval that is the product of the duration of the previous interval and a

mean 1 truncated normal variate with variance sigma-2. Data analyses indicated that the initial

value of the interval generator during a period of nystagmus, termed tau-0, is proportional to

the inverse square root of slow phase eye velocity. Further, if the eye was deviated in the slow

phase direction (re mean eye position) when the slow phase began, the slow phase duration

was consistent with a single cycle of the basic interval generator. However, if the eye was

deviated in the fast phase direction, the distribution of the durations of the ensuing slow

phases indicated that a proportion of the slow phases were produced by more than one cycle of

the basic interval generator. This phenomenon is termed "skipping a beat" and occurs with

probability p(s). Finally, the amplitude of fast phases behaved as a linear function of eye

position at the fast phase onset and the product of tau-0 and slow phase eye velocity. A

computer simulation reproduced the observed distribution of slow phase durations, the

proportion of fast phases in the fast phase and slow phase directions and the distribution of eye

positions at the onset and end of fast phases. This novel model suggests that both timing and

eye position information contribute to the alternation of nystagmus fast and slow phases.



Ball, K. and R. Sekuler (1982). “A specific and enduring improvement in visual motion

discrimination.” Science 218(4573): 697-698.

Reports an enduring alteration in vision that is specific to the stimulus on which an observer is

trained. Rather than resulting from an increased ability to select a critical feature of the

stimulus, this form of perceptual learning may be related to changes in the selectivity of

elements in the visual system. Since previous studies have suggested that motion perception is

plastic, the present authors attempted to train an observer's discrimination of the direction of

moving targets. Before training, the authors measured how well observers discriminated small

differences in direction of motion. Discrimination was assessed around 8 different directions:

0, 45, 90, 135, 180, 225, 270, and 315|. Eight observers (including one of the authors) served

as Ss. Stimuli were bright, spatially random dots moving along parallel paths over the face of

a CRT. Results show that training improved Ss' ability to discriminate between 2 similar

directions of motion. This gradual improvement was specific to the direction on which an S

was trained, and it endured for several months. It is concluded that improvement does not

affect motion perception generally, nor does it depend on recognition of the details of the

movement. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 736 of 887

in PsycINFO 1978-1984



Ball, K., R. Sekuler, et al. (1983). “Detection and identification of moving targets.” Vision Research

23(3): 229-238.

Followed-up an earlier detection experiment by 2 of the present authors (see record 1982-

08958-001) in which human Ss often greatly misperceived the direction of movement of a

moving target from a blank field. Three experiments explored how judgments of direction of

motion might actually be dissociated from the ability to detect a moving target by comparing

detection of moving random-dot patterns to identification of the pattern's direction of

movement. Results show that under most circumstances, there was a large discrepancy

between the ease of seeing a moving stimulus and the ability to assess its direction. Unless the

separation between possible directions of motion is extremely great, observers may not always

correctly identify the direction presented: They may see a moving target but still not know in

what direction it is moving. (17 ref) (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 732 of 887 in PsycINFO 1978-1984



Baloch, A. A., S. Grossberg, et al. (1999). “Neural model of first-order and second-order motion

perception and magnocellular dynamics.” Journal of the Optical Society of America a-Optics

Image Science and Vision 16(5): 953-978.

A neural model of motion perception simulates psychophysical data concerning first-order and

second-order motion stimuli, including the reversal of perceived motion direction with

distance from the stimulus (Gamma display), and data about directional judgments as a

function of relative spatial phase or spatial and temporal frequency. Many other second-order

motion percepts that have been ascribed to a second non-Fourier processing stream can also be

explained in the model by interactions between ON and OFF cells within a single;

neurobiologically interpreted magnocellular processing stream. Yet other percepts may be

traced to interactions between form and motion processing streams, rather than to processing

within multiple motion processing streams. The model hereby explains why monkeys with

lesions of the parvocellular layers, but not of the magnocellular layers, of the lateral geniculate

nucleus (LGN) are capable of detecting the correct direction of second-order motion, why

most cells in area MT are sensitive to both first-order and second-order motion, and why after

2-amino-4-phosphonobutyrate injection selectively blocks retinal ON bipolar cells, cortical

cells are sensitive only to the motion of a moving bright bar's trailing edge. Magnocellular

LGN cells show relatively transient responses, whereas parvocellular LGN cells show

relatively sustained responses. Correspondingly, the model bases its directional estimates on

the outputs of model ON and OFF transient cells that are organized in opponent circuits

wherein antagonistic rebounds occur in response to stimulus offset. Center-surround

interactions convert these ON and OFF outputs into responses of lightening and darkening

cells that are sensitive both to direct inputs and to rebound responses in their receptive field

centers and surrounds. The total pattern of activity increments and decrements is used by

subsequent processing stages (spatially short-range filters, competitive interactions, spatially

long-range filters, and directional grouping cells) to determine the perceived direction of

motion. (C) 1999 Optical Society of America [S0740-3232(99)02105-5].



Baltes, P. B. and K. Wender (1971). “Age differences in pleasantness of visual patterns of different

variability in late childhood and adolescence.” Child Development 42(1): 47-55.

Investigated pleasantness of 2 kinds of visual patterns (random shaped polygons and random

dot configurations) of 14 different levels of variability in 240 9-, 11-, 13-, and 15-yr-old male

and female Ss, using a cross-sectional approach. A monotonically increasing function between

degree of variability and verbally stated pleasantness was found for all age groups. In addition,

a relatively weak but significant Age * Variability interaction resulted with the older Ss rating

low-variability random shapes as less pleasant. Results are interpreted in the framework of

research relating stimulus complexity to exploratory behavior. Earlier data, suggesting an age-

invariant preference for an intermediate level of variability, are interpreted as representing a

methodological artifact primarily due to biased sampling of the stimulus domain. (17 ref.)

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 874 of 887 in

PsycINFO 1967-1977



Bando, T. (1993). “Discrimination of Random-Dot Texture Patterns in Bluegill Sunfish, Lepomis-

Macrochirus.” Journal of Comparative Physiology a-Sensory Neural and Behavioral

Physiology 172(6): 663-669.

In order to study the ability of fish to perceive and distinguish textures visually, bluegill

sunfish (Lepomis macrochirus) were trained to discriminate between pairs of artificial texture

patterns. Random dot patterns with different statistical dot distributions were presented to the

fish as artificial texture patterns. The results indicate that bluegills have the ability to

discriminate many pairs of patterns with different statistical features of dot distributions which

have different appearance in texture. This suggests that texture could be one of the important

visual features bluegill sunfish recognize and utilize.



Banton, T. and B. I. Bertenthal (1996). “Infants' sensitivity to uniform motion.” Vision Research

36(11): 1633-1640.

Uniform motion across the retina is a powerful cue to the perception of self-motion. In spite of

its importance for adaptive functioning, little is known about the early development of

uniform motion sensitivity. Six-, 12-, and 18-week-old infants viewed random-dot

kinematograms depicting leftward or rightward uniform motion. The display induced

optokinetic nystagmus (OKN), which a trained observer used to judge the direction of target

motion. Both speed of motion and directional coherence were varied to obtain independent

motion detection thresholds. Infants of all three ages could detect uniform motion, and their

detection thresholds were constant during this period of development. This is in contrast to the

clear improvements in relative motion sensitivity noted previously between 6 and 18 weeks of

age with a preferential looking (PL) paradigm. The developmental differences between these

studies may result from: (1) separate mechanisms for detecting uniform (absolute) and

differential (relative) motion; or (2) separate mechanisms underlying OKN and PL response

measures. Copyright (C) 1996 Elsevier Science Ltd.



Banton, T., B. I. Bertenthal, et al. (1999). “Infants' sensitivity to statistical distributions of motion

direction and speed.” Vision Research 39(20): 3417-3430.

Adults combine different local motions to form a global percept of motion. This study

explores the origins of this process by testing how perturbations of local motion influence

infants' sensitivity to global motion. Infants at 6-, 12-, and 18-weeks of age viewed random

dots moving with a gaussian distribution of dot directions defined by a mean of 0 degrees

(rightward) or 180 degrees (leftward) and a standard deviation (SD) of 0, 34, or 68 degrees. A

well-practiced observer used infants' optokinetic responses to judge the direction of stimulus

motion. Infants were studied both cross-sectionally and longitudinally. Direction

discrimination was relatively high at all ages when the SD was 0 degrees. When the SD was

34 or 68 degrees, performance declined with age. Adult performance was nearly perfect at

these SDs. A similar developmental pattern was found with distributions of dot speed. The

decline in infant performance is consistent with the development of both neural tuning and

receptive field size. The subsequent improvement by adulthood suggests the development of

additional processes such as long-range interactions. (C) 1999 Elsevier Science Ltd. All rights

reserved.



Banton, T., K. Dobkins, et al. (2001). “Infant direction discrimination thresholds.” Vision Research

41(8): 1049-1056.

Although adults can detect direction differences as small as 1 are degree, the ability of infants

to discriminate direction of motion is less clear. This study measures the precision with which

6-, 12-, and 18-week-old infants discriminate direction of motion. Infants viewed random dot

kinematograms in which a direction difference between the target and background dots

defined a circular target. The target was then placed into continuous motion. An FPL

paradigm was used to assess infants' preference for the target as a function of the direction

difference between the target and background dots. Direction discrimination thresholds with a

moving target were indeterminate at 6 weeks of age, 22 degrees at 12 weeks of age and 17

degrees at 18 weeks of age. This precision was maintained across different testing conditions.

However, performance dropped markedly when dot motion was presented within a flickering

stationary target. It was concluded that infants can make relatively fine discriminations of

motion direction if given an engaging stimulus. (C) 2001 Elsevier Science Ltd. Ah rights

reserved.



Banton, T. and D. M. Levi (1993). “Spatial Localization of Motion-Defined and Luminance-Defined

Contours.” Vision Research 33(16): 2225-2237.

Thresholds for the vernier alignment of contours defined by luminance and coherent random-

dot motion were measured. The luminance-defined contours were localized with a precision

better than the receptor grain, while the motion-defined contours were localized more poorly

than this limit. When motion-defined and luminance-defined targets were matched for dot

density, vernier thresholds were equivalent at low densities. When the targets were also

equated for perceived contrast, the vernier thresholds became equivalent at higher densities as

well. These results suggest that the precision with which motion-defined contours are

localized is contrast and sample limited. Next, the localization mechanism for motion-defined

targets was investigated. Length summation limits were similar for motion-defined and

luminance-defined targets, suggesting that these targets could be localized by a common

mechanism. Vernier targets were then flanked by two additional bars. Motion-defined flanks

interfered with the localization of motion-defined targets and luminance-defined flanks

interfered with the localization of luminance-defined targets. However, motion-defined and

luminance-defined bars did not interact to produce spatial interference. This result indicates

that the mechanisms for localizing luminance-defined and motion-defined targets are

independent. We suggest that parallel mechanisms govern the vernier localization of motion-

defined and luminance-defined targets.



Barbur, J. L., A. J. Harlow, et al. (1992). “Pupillary Responses to Stimulus Structure, Color and

Movement.” Ophthalmic and Physiological Optics 12(2): 137-141.

Pupillary responses to stimuli which favour the preferential stimulation of neural mechanisms

involved in the detection of visual attributes such as colour, spatial structure, movement and

light flux changes on the retina have been measured and compared. Pupil responses to a

decrement in stimulus luminance (i.e., a flash of darkness), suggest that at least three

components are involved in this response, their relative contribution being determined largely

by stimulus size, contrast and presentation time. A comparison of pupil responses to gratings

of equal and lower space-averaged luminance shows that the amplitude of pupillary

constriction at grating onset for the equal luminance condition is about twice that measured

with similar gratings in the lower luminance condition. Pupillary responses to chromatic

isoluminant gratings are in general of longer latency when compared to responses of similar

amplitude elicited by achromatic gratings. Small pupillary constrictions elicited by the onset

of coherent movement in dynamic, random dot patterns are also demonstrated under stimulus

conditions which eliminate pupillary responses to sudden light flux changes on the retina. The

results support an earlier hypothesis which suggests that the onset of sudden changes in neural

activity in the visual cortex when a visual stimulus is presented to the eye causes an overall

perturbation which weakens transiently the regulatory inhibitory input to the pupillomotor

nucleus. This, in turn, results in a transient increase in the efferent parasympathetic

innervation of the iris sphincter muscle and hence the observed constriction of the pupil. The

characteristics of the pupillary response reflect the properties of the mechanisms and the

number of neurones which participate in the detection of each simulus attribute.



Barlow, H. (2001). “The exploitation of regularities in the environment by the brain.” Behavioral and

Brain Sciences 24(4): 602-+.

Statistical regularities of the environment are important for learning, memory, intelligence,

inductive inference, and in fact, for any area of cognitive science where an information-

processing brain promotes survival by exploiting them. This has been recognised by many of

those interested in cognitive function, starting with Helmholtz, Mach, and Pearson, and

continuing through Craik, Tolman, Attneave, and Brunswik. In the current era, many of us

have begun to show how neural mechanisms exploit the regular statistical properties of natural

images. Shepard proposed that the apparent trajectory of an object when seen successively at

two positions results from internalising the rules of kinematic geometry, and although

kinematic geometry is not statistical in nature, this is clearly a related idea. Here it is argued

that Shepard's term, "internalisation," is insufficient because it is also necessary to derive an

advantage from the process. Having mechanisms selectively sensitive to the spatio-temporal

patterns of excitation commonly experienced when viewing moving objects would facilitate

the detection, interpolation, and extrapolation of such motions, and might explain the twisting

motions that are experienced. Although Shepards explanation in terms of Chasles' rule seems

doubtful, his theory and experiments illustrate that local twisting motions are needed for the

analysis of moving objects and provoke thoughts about how they might be detected.



Barlow, H. and S. P. Tripathy (1997). “Correspondence noise and signal pooling in the detection of

coherent visual motion.” Journal of Neuroscience 17(20): 7954-7966.

In the random dot kinematograms used to analyze the detection of coherent motion in the

middle temporal visual area (MT) and in psychophysical experiments the exact way that dots

are paired between successive presentations is not known by the observer We show how to

calculate the limit to coherence threshold caused by this uncertainty, which we call

''correspondence noise.'' We compare ideal thresholds limited only by this noise with those of

human observers when dot density, ratio of dot numbers in two fields, area of stimulus,

number of fields, and method of generation of the coherent dots are varied. The observed

thresholds vary in the same way as the ideal thresholds over wide ranges, but they are much

higher. We think this difference is because the ideal detector takes advantage of the high

precision with which dots are placed in the kinematograms, whereas the neural motion system

can only operate with low precision. When kinematograms are generated with decreased

precision of dot placement, the ideal detector no longer has this advantage, and the gap

between ideal and actual performance is greatly reduced. Because the signals that result from

objects moving in the real world are scattered over broad ranges of direction and velocity,

high precision is not needed, and it is advantageous for the motion system to pool information

over broad ranges. Other mismatches between kinematograms and the neural motion system,

and internal noise, may also elevate human thresholds relative to the ideal detector. The

importance of external noise suggests that the neurons of MT form a vast array of optimal

filters, each matched to a different combination of parameters in the multidimensional space

required to define motion in patches of the visual field.



Barlow, H. B. (1978). “The efficiency of detecting changes of density in random dot patterns.” Vision

Research 18: 637-650.

The ability of subjects to detect targets of higher average dot density embedded in

backgrounds of random dots was measured. As the average density of dots in the target is

raised above the average density in the background the value of d' for detecting the target rises

linearly.

Barlow, H. B. and B. C. Reeves (1979). “The versatility and absolute efficiency of detecting mirror

symmetry in random dot displays.” Vision Research 19(7): 783-793.

Studied the detection of mirror symmetry by measuring discriminability between 2

populations of dot displays that contained mirror pairs and random dots in different

proportions. The 2 authors served as Ss. The difficulty of the task was varied by changing the

proportions of paired dots in the 2 populations and also by changing the accuracy of

positioning the paired dots. Symmetry was detected in brief exposures, monocularly or

binocularly, when the axis was not vertical and when the axis was not central in the visual

field. The mechanism is therefore versatile. Its efficiency can be measured when the pairing is

imperfect, for unpaired dots then fall where a pair is expected, thus causing the spurious

appearance of a pair. When the pairing has an accuracy of about +-6' vertically and

horizontally, an ideal mechanism would achieve discriminability values about double those

attained by Ss, who were thus using 25% of the statistical information available, which is a

high figure considering the versatility and complexity of the mechanisms required. (24 ref)

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 790 of 887 in

PsycINFO 1978-1984



Barraza, J. F. and N. M. Grzywacz (2002). “Measurement of angular velocity in the perception of

rotation.” Vision Research 42(21): 2457-2462.

Humans are sensitive to the parameters of translational motion, namely, direction and speed.

At the same time, people have special mechanisms to deal with more complex motions, such

as rotations and expansions. One wonders whether people may also be sensitive to the

parameters of these complex motions. Here, we report on a series of experiments that explore

whether human subjects can use angular velocity to evaluate how fast a rotational motion is.

In four experiments, subjects were required to perform a task of speed-of-rotation

discrimination by comparing two annuli of different radii in a temporal 2AFC paradigm.

Results showed that humans could rely on a sensitive measurement of angular velocity to

perform this discrimination task. This was especially true when the quality of the rotational

signal was high (given by the number of dots composing the annulus). When the signal quality

decreased, a bias towards linear velocity of 5-80% appeared, suggesting the existence of

separate mechanisms for angular and linear velocity. This bias was independent from the

reference radius. Finally, we asked whether the measurement of angular velocity required a

rigid rotation, that is, whether the visual system makes only one global estimate of angular

velocity. For this purpose, a random-dot disk was built such that all the dots were rotating with

the same tangential speed, irrespectively of radius. Results showed that subjects do not

estimate a unique global angular velocity, but that they perceive a non-rigid disk, with angular

velocity falling inversely proportionally with radius. (C) 2002 Elsevier Science Ltd. All rights

reserved.



Barris, M. C., I. Bodiswollner, et al. (1980). “Bode Plots of Cortical Potentials-Evoked by Dynamic

Random-Dot Correlograms.” Journal of the Optical Society of America 70(12): 1597-1598.



Barton and J. A. Sharpe (1997). “Motion direction discrimination in blind hemifields.” Annals of

Neurology 41(2): 255-264.

Tested motion direction discrimination with random dot cinematograms (RDC) projected into

the contralateral homonymous visual field defects of 10 patients with unilateral cerebral

hemispheric lesions. Five Ss had medial occipital lesions that spared the putative motion area

in lateral occipitotemporal cortex and the optic radiations and other white matter tracts

proximal to this site. The other 5 had lesions involving this area or the proximal optic

radiations. No patient in either group discriminated motion direction in signal/noise RDCs at a

level better than chance, and the performance of Ss with lesions restricted to medial occipital

lobe did not differ from that of Ss with lateral occipital or optic radiation lesions. A subgroup

of patients with medial occipital lesions also performed a "frequency of discrimination"

experiment, using 100% coherent dot motion with stimulus velocities ranging as high as 79.4

deg./sec. Their results were also no better than chance. Sparing of the putative motion area in

lateral occipitotemporal cortex and its input fibers is not a sufficient condition for residual

direction discrimination with RDCs in homonymous visual field defects. (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 301 of 887 in PsycINFO 1996-1997

Barton, J. J. S., M. Rizzo, et al. (1996). “Optical blur and the perception of global coherent motion in

random dot cinematograms.” Vision Research 36(19): 3051-3059.

We evaluated the effect of +3.25 dioptres of optical blur on the discrimination of motion

direction in random dot cinematograms. Dot displacement between frames varied from 2.1 to

63' of visual angle while the temporal interval was held constant. Optical blur worsened

discrimination in three normal subjects at displacements below 16', but improved

discrimination at displacements of 21' or more. In a second experiment, two subjects viewed

equivalent velocity stimuli constructed with different combinations of temporal interval and

spatial displacement. Results showed that the effect of blur was specific to displacement and

not velocity. Furthermore, varying the dot density of the display showed that the effect of blur

correlated with dot displacement and not the probability of dot mismatches. Since optical blur

attenuates high spatial frequencies, this suggests that high spatial frequencies are important for

motion perception when dot displacements are less than 16' to 21', but reduce motion

perception at larger dot displacements. The use of random dot cinematograms in populations

must take into account stimulus displacement and optical causes of reduced spatial acuity.

Copyright (C) 1996 Elsevier Science Ltd.



Barton, J. J. S. and J. A. Sharpe (1997). “Motion direction discrimination in blind hemifields.” Annals

of Neurology 41(2): 255-264.

We tested motion direction discrimination with random dot cinematograms (RDCs) projected

into the contralateral homonymous visual field defects of 10 patients with unilateral cerebral

hemispheric lesions. Five patients had medial occipital lesions that spared the putative motion

area in lateral occipitotemporal cortex and the optic radiations and other white matter tracts

proximal to this site. The other 5 had lesions involving this area or the proximal optic

radiations. Eye position was monitored to ensure fixation. No patient in either group

discriminated motion direction in signal/noise RDCs at a level better than chance, and the

performance of those with lesions restricted to medial occipital lobe did not differ from those

with lateral occipital or optic radiation lesions. A subgroup of patients with medial occipital

lesions also performed a ''frequency of discrimination'' experiment, using 100% coherent dot

motion with stimulus velocities ranging as high as 73.4 degrees/sec. Their results on these

tests were also no better than chance. Sparing of the putative motion area in lateral

occipitotemporal cortex and its input fibers is not a sufficient condition for residual direction

discrimination (blindsight) with RDCs in homonymous visual field defects.



Barton, J. J. S., J. A. Sharpe, et al. (1995). “Retinotopic and Directional Defects in Motion

Discrimination in Humans with Cerebral-Lesions.” Annals of Neurology 37(5): 665-675.

We investigated the discrimination of motion direction in peripheral and central vision in 23

patients with unilateral cerebral hemispheric lesions on computed tomography or magnetic

resonance imaging. We used random dot cinematograms that determined a percent coherence

motion threshold for 16 points in the peripheral field and for four directions separately in

central vision. We measured asymmetry of right- versus left-field peripheral discrimination

(retinotopic defects) and asymmetry of central discrimination for rightward versus leftward

motion (directional defects), compared with normal subjects. Five patients had directional

asymmetries of foveal motion perception, all worse for motion toward the side of their lesions.

One patient had a bidirectional defect for the perception of horizontal motion. For 3 of these 6,

the average of all horizontal and vertical motion discrimination thresholds was also elevated.

Two had contralateral retinotopic defects. One of these also had an ipsidirectional foveal

defect, but the other did not. The remaining 5 patients with ipsidirectional foveal defects had

hemianopias that precluded testing for coexistent retinotopic defects. The lesions of the 6

patients with ipsidirectional defects overlapped in white matter underlying the lateral temporo-

occipital cortex, at the junction of Brodmann areas 19 and 37. In contrast, lesions of patients

without directional defects spared this region.



Barton, J. J. S., J. A. Sharpe, et al. (1996). “Directional defects in pursuit and motion perception in

humans with unilateral cerebral lesions.” Brain 119: 1535-1550.

We tested motion perception and smooth pursuit in 26 patients with unilateral cerebral

hemispheric lesions. We used random dot cinematograms to test motion direction

discrimination. We measured pursuit gain as they followed a predictable sinusoidal target

moving horizontally at three different frequencies, and an unpredictable horizontal step-ramp

target in the ipsilateral hemi-field. Six patients had defects in motion perception when the

targets were moving towards the side of the lesion ('ipsi-directional' defects) and two had

bidirectional defects. Motion perception defects occurred with lesions of the junction of

Brodmann areas 19 and 37, a putative human homologue of the monkey V5 complex. Seven

patients had ipsi-directional pursuit defects, Jive of whom had damage to the posterior limb of

the internal capsule. Only two patients had ipsi-directional defects of both motion perception

and sinusoidal smooth pursuit. Four patients had ipsi-directional defects of motion perception

alone, and five patients had ipsi-directional pursuit defects alone. The two patients with bi-

directional defects in motion perception had normal sinusoidal smooth pursuit. Patients with

lesions at the 19/37 junction and defects of motion perception alone had normal pursuit of

unpredictable step-ramp targets in the ipsilateral hemi-field. In contrast, patients with ipsi-

directional sinusoidal pursuit defects had decreased ipsi-directional and increased contra-

directional velocities with step-ramp targets. No patient group had a motion-specific

directional defect in saccadic accuracy. We conclude that neither predictable nor unpredictable

pursuit is necessarily impaired by lesions of the 19/37 junction that cause ipsi-directional

defects of motion perception. These dissociations between smooth pursuit and motion

perception provide evidence that the pursuit system operates as an interconnected network

with parallel pathways, rather than as a simple sequential hierarchy of cortical areas.



Bauer, R. and W. Jordan (1993). “Different Anisotropies for Texture and Grating Stimuli in the Visual

Map of Cat Striate Cortex.” Vision Research 33(11): 1447-1450.

A comparison was made of the directional preferences of cat area 17 cells tested with two

different stimuli, gratings and random-dot patterns. Depending on the stimulus, different

distributions of direction preferences (anisotropies) were found in the same cells of the central

representation of upper layers. With gratings most common preferred directions were vertical

and horizontal. With textures, however, horizontal preferred directions were most common. In

contrast, lower layer neurons had a bias for vertical preferred directions regardless of the type

of stimulus used.



Beauchamp, M. S. (1998). FMRI of attention in the human visual motion processing system.

We performed a series of Functional MRI experiments to delineate the complete system of

human cortical areas involved in a visual motion task and study their modulation by attention.

Human subjects discriminated between different point speeds in each half of an annulus

defined by coherent motion within a dynamic random dot field. Our experiments revealed a

low-level network, including area V1, which is important for processing local motion, as

evidenced by equivalent responses to coherently and incoherently moving points. A higher-

level network included a strip of dorsal occipital-parietal cortex running from the ventrolateral

location of hMT (proposed human homolog of macaque area MT) to the banks of the

intraparietal sulcus. This network responded well to the motion defined annulus but poorly to

incoherently moving points, suggesting that it forms a cortical system capable of extracting

and using global motion information. When subjects performed a speed discrimination task

which directed their spatial attention to a peripherally presented annulus and their featural

attention to the speed of points in the annulus, activity in hMT+ was maximal. If subjects were

instead asked to discriminate the color of points in the annulus, the magnitude and volume of

activation in hMT+ fell to 64% and 35%, respectively, of the previously observed maximum

response. In another experiment, subjects were asked to direct their spatial attention away

from the annulus towards the fixation point in order to detect a subtle change in luminance.

The response magnitude and volume dropped to 40% and 9% of maximum. These

experiments demonstrate that both spatial and featural attention modulate hMT+ and that their

effects can work in concert to modulate cortical activity. The high degree of modulation by

attention suggests that an understanding of the stimulus-driven properties of visual cortex

needs to be complemented with an investigation of the effects of task-related factors on visual

processing. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 221 of 887

in PsycINFO 1998



Becker, S., C. Bowd, et al. (1999). “Occlusion contributes to temporal processing differences between

crossed and uncrossed stereopsis in random-dot displays.” Vision Research 39(2): 331-339.

Stereoscopic depth discrimination was investigated in crossed and uncrossed directions using

stimuli defined by binocular disparity differences embedded in dynamic random-dot

stereograms. Across three experiments, fixation was directed to a point on the display screen

(which placed crossed stimuli in front of, and uncrossed stimuli behind, the background dots

of the stereogram), to a point in front of the display screen (which placed both crossed and

uncrossed stimuli in front of the background dots), and to a point behind the display screen

(which placed both crossed and uncrossed stimuli behind the background dots). Results

showed that depth discrimination was always good when the stimuli appeared in front of the

background dots of the stereogram, whereas discrimination was always poor when the stimuli

appeared behind the background dots. These results suggest that differences. between crossed

and uncrossed stereopsis as reported in past research arose, in part, from effects related to

occlusion. (C) 1998 Elsevier Science Ltd. All rights reserved.



Becker, S. and G. E. Hinton (1992). “Self-Organizing Neural Network That Discovers Surfaces in

Random-Dot Stereograms.” Nature 355(6356): 161-163.

THE standard form of back-propagation learning 1 is implausible as a model of perceptual

learning because it requires an external teacher to specify the desired output of the network.

We show how the external teacher can be replaced by internally derived teaching signals.

These signals are generated by using the assumption that different parts of the perceptual input

have common causes in the external world. Small modules that look at separate but related

parts of the perceptual input discover these common causes by striving to produce outputs that

agree with each other (Fig. 1a). The modules may look at different modalities (such as vision

and touch), or the same modality at different times (for example, the consecutive two-

dimensional views of a rotating three-dimensional object), or even spatially adjacent parts of

the same image. Our simulations show that when our learning procedure is applied to adjacent

patches of two-dimensional images, it allows a neural network that has no prior knowledge of

the third dimension to discover depth in random dot stereograms of curved surfaces.



Becker, S. and G. E. Hinton (1993). “Learning mixture models of spatial coherence.” Neural

Computation 5(2): 267-277.

Reviews work by S. Becker and G. E. Hinton (1992) describing an unsupervised learning

procedure that discovers spatially coherent properties of the world by maximizing the

information that parameters extracted from different parts of the sensory input convey about

some common underlying cause. When given random-dot stereograms of curved surfaces, this

procedure learns to extract surface depth and interpolate the depth at 1 location. Two new

models are proposed that handle surfaces with discontinuities. The 1st model attempts to

detect cases of discontinuities and reject them. The 2nd model develops a mixture of expert

interpolators and learns to detect the locations of discontinuities and to invoke specialized,

asymmetric interpolators that do not cross the discontinuities. (PsycINFO Database Record (c)

2002 APA, all rights reserved) Record 491 of 887 in PsycINFO 1993-1995



Becker, S. and G. E. Hinton (1993). “Learning Mixture-Models of Spatial Coherence.” Neural

Computation 5(2): 267-277.

We have previously described an unsupervised learning procedure that discovers spatially

coherent properties of the world by maximizing the information that parameters extracted

from different parts of the sensory input convey about some common underlying cause. When

given random dot stereograms of curved surfaces, this procedure learns to extract surface

depth because that is the property that is coherent across space. It also learns how to

interpolate the depth at one location from the depths at nearby locations (Becker and Hinton

1992b). In this paper, we propose two new models that handle surfaces with discontinuities.

The first model attempts to detect cases of discontinuities and reject them. The second model

develops a mixture of expert interpolators. It learns to detect the locations of discontinuities

and to invoke specialized, asymmetric interpolators that do not cross the discontinuities.



Bell, H. H. and J. S. Lappin (1979). “The detection of rotation in random-dot patterns.” Perception and

Psychophysics 26(5): 415-417.

A study of 3 Ss' ability to detect rotation in circular, random dot patterns found that percentage

of correct discriminations decreased as the extent of rotation increased and as the interstimulus

interval increased. Results are analogous with those for lateral translation of rectangular

patterns; they are incompatible with a neural process of specifically tuned motion analyzers,

but are compatible with one that detects coherent organization of patterns in time and space. (7

ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 783 of 887 in

PsycINFO 1978-1984

Benzing, W. C. and L. R. Squire (1989). “Preserved learning and memory in amnesia: Intact

adaptation-level effects and learning of stereoscopic depth.” Behavioral Neuroscience 103(3):

538-547.

Amnesic patients and control Ss performed similarly on 2 memory tests. In experiments 1A

and 1B, amnesic patients exhibited intact adaptation-level effects: An experience lifting and

judging a group of weights influenced their judgments of a 2nd group of weights 20-25 min

later. The effect did not depend on peripheral accommodation, because Ss used 1 hand during

their 1st encounter with the weights and the opposite hand during their 2nd encounter. In

Experiment 2, amnesic patients acquired at a normal rate the ability to perceive binocular

depth using random-dot stereograms. In both experiments, amnesic patients benefited from

recent experience, despite the fact that they could not remember their prior experience

accurately. The preserved memory abilities demonstrated here appear to be examples of

implicit, or nondeclarative, memory. (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 598 of 887 in PsycINFO 1988-1989



Beran, M. J., D. M. Rumbaugh, et al. (1998). “Chimpanzee (Pan troglodytes) counting in a

computerized testing paradigm.” Psychological Record 48(1): 3-19.

Using computer-mediated joystick manipulation, the ability of a common chimpanzee (Pan

troglodytes) to select arrays of items equal to a given target number was examined. A random

dot condition was included in which all sequence cues were eliminated as a means to reach the

target numbers 1 to 4. The participant, Austin, had only the quantity of items already selected

as a record of how high the count had progressed. Performance on the random dot trials was

found to be significantly above chance and improvement over time was also statistically

significant. Results of this experiment provide evidence that Austin behaved with a knowledge

that the quantity of items selected was the objective of the task rather than adhering rigidly to

any specific pattern of selection. The results indicate that Austin had the ability to discriminate

the number of items needed to reach the target number and then select items individually to

reach that target quantity. (PsycINFO Database Record (c) 2002 APA, all rights

reserved)(journal abstract) Record 252 of 887 in PsycINFO 1998



Beran, M. J., D. M. Rumbaugh, et al. (1998). “Chimpanzee (Pan troglodytes) counting in a

computerized testing paradigm.” Psychological Record 48(1): 3-19.

Using computer-mediated joystick manipulation, the ability of a common chimpanzee (Pan

troglodytes) to select arrays of items equal to a given target number was examined. A random

dot condition was included in which all sequence cues were eliminated as a means to reach the

target numbers 1 to 4. The participant, Austin, had only the quantity of items already selected

as a record of how high the count had progressed. Performance on the random dot trials was

found to be significantly above chance and improvement over time was also statistically

significant. Results of this experiment provide evidence that Austin behaved with a knowledge

that the quantity of items selected was the objective of the task rather than adhering rigidly to

any specific pattern of selection. The results indicate that Austin had the ability to discriminate

the number of items needed to reach the target number and then select items individually to

reach that target quantity.



Berends, E. M. and C. J. Erkelens (2001). “Adaptation to disparity but not to perceived depth.” Vision

Research 41(7): 883-892.

The purpose of the present study was to investigate whether adaptation can occur to disparity

per se. The adapting stimuli were large random-dot patterns of which the two half-images

were transformed such that the depth effects induced by the vertical transformations were

nulled by horizontal transformations. Thus, the adapting stimuli were perceptually the same,

whereas the disparity fields differed from each other. The adapting stimuli were presented for

five minutes. During that period, the percept of a fronto-parallel surface did not change. After

the adapting period, subjects perceived a thin untransformed strip as either slanted or curved

depending on the adapting transformation. The thin strips provided negligible information

about the vertical disparity field. In a forced-choice task we measured the amount of

horizontal transformation that was required to null the acquired adaptation. We found that the

amounts of horizontal transformation required to perceive the test strip fronto-parallel were

significantly different from zero. We conclude that the visual system can adapt to disparity

signals in the absence of a perceptual drive. (C) 2001 Elsevier Science Ltd. All rights

reserved.

Bergua, A. and W. Skrandies (2000). “An early antecedent to modern random dot stereograms - 'The

Secret Stereoscopic Writing' of Ramon y Cajal.” International Journal of Psychophysiology

36(1): 69-72.

The use of computerized random dot stimuli in modern neuroscience was introduced by Julesz

in the 1960s. This method made it possible to study exclusively cortical processing of

binocular information by disparity-sensitive neurons, and it has attained widespread use

among neuroscientists and psychologists. It is now largely forgotten that in the last century,

the famous neuroanatomist Ramon y Cajal had worked on random dot stereograms as a means

of encoding written information. A brief note was finally published in a Spanish journal on

photography in 1901. We present a translation of this text and summarize the early ideas on

random dot stereograms, and we also supply a brief historical account on stereoscopic

perception. (C) 2000 Elsevier Science B.V. All rights reserved.



Bergua, A. and W. Skrandies (2000). “An early antecedent to modern random dot stereograms: 'The

Secret Stereoscoping Writing' of Ramon y Cajal.” International Journal of Psychophysiology

36(1): 69-72.

The use of computerized random dot stimuli in modern neuroscience was introduced by B.

Julesz in the 1960s. This method made it possible to study exclusively cortical processing of

binocular information by disparity-sensitive neurons, and it has attained widespread use

among neuroscientists and psychologists. It is now largely forgotten that in the last century,

the famous neuroanatomist S. Ramon y Cajal had worked on random dot stereograms as a

means of encoding written information. A brief note was finally published in a Spanish journal

on photography in 1901. The authors present a translation of Ramon y Cajal's original text and

summarize the early ideas on random dot stereograms. A brief historical account on

stereoscopic perception is also presented. (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 146 of 887 in PsycINFO 2000



Bergum, B. and L. E. Flamm (1979). “Reversibility and apparent tridimensionality.” Bulletin of the

Psychonomic Society 14(3): 193-196.

Measures of perceived tridimensionality and reversal rates were taken on 101 undergraduates

to determine the relationship between these measures. Three examples each of the Necker and

Mach reversible figures (E. L. Porter, 1938) were employed. It was hypothesized that

perceived tridimensionality would predict reversal rates at least as accurately as would

objective measures of figural complexity, but without recourse to considerations of which

"family" of geometric figures might be involved. The results confirm the prediction. Perceived

tridimensionality predicted reversal rates both within and across types of figures.



Bertamini, M., J. D. Friedenberg, et al. (1997). “Detection of symmetry and perceptual organization:

The way a lock-and-key process works.” Acta-Psychologica 95(2): 119-140.

Explored how figure-ground organization affected 100 undergraduates' detection of

symmetry. Exp 1 studied the speed

with which observers could detect symmetry in line drawings that incorporated symmetric contours

related by reflection or translation. Detection of reflections between contours was faster

when contours belonged to a single object, whereas detection of translation was faster when contours

belonged to 2 objects. Exps 2, 3, and 4 examined whether detection of translation is

easier when a lock-and-key match is possible by manipulating the correspondence of the features or

by altering the praegnanz of the 2 parts of the image. Results indicate that perceptual

organization can alter the detectability of symmetry.



Bertamini, M. and D. R. Proffitt (2000). “Hierarchical motion organization in random dot

configurations.” Journal of Experimental Psychology-Human Perception and Performance

26(4): 1371-1386.

Motion organization has 2 aspects: the extraction of a (moving) frame of reference and the

hierarchical organization of moving elements within the reference frame. Using a

discrimination of relative motions task, the authors found large differences between different

types of motion (translation, divergence, and rotation) in the degree to which each can serve as

a moving frame of reference. Translation and divergence are superior to rotation. There are,

however, situations in which rotation can serve as a reference frame. This is due to the

presence of a second factor, structural invariants (SIs). SIs are spatial relationships persisting

among the elements within a configuration such as a collinearity among points or one point

coinciding with the center of rotation for another (invariant radius). The combined effect of

these 2 factors-motion type and SIs-influences perceptual motion organization.



Bertenthal, B. I., T. Banton, et al. (1993). “Directional Bias in the Perception of Translating Patterns.”

Perception 22(2): 193-207.

Recent findings suggest that the visual system is biased by its past stimulation to detect one

direction of motion over others. Three experiments were designed to investigate whether this

bias is mediated by the direction or by the velocity of the past stimulation, and whether this

bias is offset by contradictory pattern or depth information. Observers were presented with

two solid or random-dot patterns that moved across a display screen in antiphase. As the two

patterns reached the center of the screen, they became superimposed in such a way that their

subsequent directions were ambiguous. Results from experiment 1 showed that the probability

of perceiving these patterns as continuing to move in the same directions was significantly

greater when they moved at a constant velocity than when they moved at a variable velocity.

Results from experiments 2 and 3 revealed that this directional bias was reversed only

gradually as an increasing amount of contradictory pattern information was introduced, but

that this reversal was quite abrupt when a relatively small amount of contradictory depth

information was introduced. Collectively, these results suggest that a directional bias in the

perception of moving patterns is mediated not only by the direction of the previous

stimulation, but also by the velocity of that stimulation. Moreover, the analyses of pattern and

motion information appear relatively independent during the early stages of visual processing,

but the analyses of depth and motion information appear considerably more interdependent.



Bertenthal, B. I. and A. Bradbury (1992). “Infants Detection of Shearing Motion in Random-Dot

Displays.” Developmental Psychology 28(6): 1056-1066.

Random-dot kinematograms were used to estimate infants' thresholds for shearing motion in

the absence of flicker and position cues. The principal advantage of these stimuli is that

changes in dot position are camouflaged by the presence of numerous matching dots, thus

necessitating the detection of motion before the extraction of lor-al pattern features. Thirteen-

and 20-week-old infants were tested with a forced-choice preferential looking technique. The

target stimulus resembled a vertically oriented corrugated pattern that oscillated at 1 Hz, if,

and only if, shearing motion was detected. Infants were tested at different velocities, ranging

from 0.7-degrees/s to 5.6-degrees/s, and the results revealed minimum velocity thresholds of

3.5-degrees/s and 1.2-degrees/s for 13- and 20-week-old infants, respectively. Possible

interpretations for these results based on position- or flicker-sensitive mechanisms are

considered and are found inconsistent with the overall pattern of results. It is concluded that

infants detect shearing motion in random-dot displays with a motion-sensitive mechanism.



Bex, P. J. and S. C. Dakin (2003). “Motion detection and the coincidence of structure at high and low

spatial frequencies.” Vision Research 43(4): 371-383.

We used filtered random dot kinematograms and natural images to examine how motion

detection depends the relative locations of structures defined at low and high spatial

frequencies. The upper displacement limit of motion (D-max), the lower displacement limit

(D-min) and motion coherence thresholds were unaffected by the degree of spatial

coincidence between high and low spatial frequency structures i.e. whether they were

consistent or inconsistent with a single feature. However motion detection was possible

between band-pass filtered random dot patterns whose peak frequencies were separated by up

to 4 octaves. The first result implicates spatial frequency selective motion detectors that

operate independently. The second result implicates a motion system that can integrate the

displacements of edges defined by widely separated spatial frequencies. Both are required to

account for the two results, and they appear to operate under very similar conditions. (C) 2003

Elsevier Science Ltd. All rights reserved.



Bex, P. J., G. K. Edgar, et al. (1995). “Multiple Images Appear When Motion Energy Detection Fails.”

Journal of Experimental Psychology-Human Perception and Performance 21(2): 231-238.

Under certain conditions, multiple images trail behind a target moving across a cathode ray

oscilloscope. Given the relatively sluggish temporal response of the visual system, it is

surprising that when an image is rapidly displaced, multiple images are not seen under most

circumstances. The authors have explored the conditions under which multiple images appear.

The velocity at which multiple images first appear (aliasing velocity) was recorded across a

range of image update rates for a drifting bar and for band-pass and low-pass filtered bars.

Multiple images were found to appear when a fixed spatial displacement was exceeded

between image updates. The value of this displacement was approximately invariant with drift

speed. The effects on aliasing velocity of band-pass and low-pass filtering are similar to those

reported for motion detection after comparable manipulations of a random dot kine-matogram

(R. Cleary and O. J. Braddick, 1990a, 1990b). The findings suggest that multiple imaging

occurs when motion energy detection fails.



Bilodeau, L. and J. Faubert (1999). “Global motion cues and the chromatic system.” Journal of the

Optical Society of America a-Optics Image Science and Vision 16(1): 1-5.

The capacity of the isolated chromatic system to perceive global motion was tested in a 40-deg

visual field by use of random-dot kinematograms. The method of equivalent cone: contrasts

was used to directly compare the chromatic and the achromatic systems. The minimum

number of dots necessary to correctly identify the motion direction was on the order of 20%

for the isochromatic conditions, whereas thresholds were rarely obtained in the chromatic

conditions. For both the isochromatic and the chromatic conditions, the central visual field

was the most sensitive area, whereas the periphery was slightly less sensitive. This study

suggests that the chromatic system does not efficiently integrate local motion cues to generate

a global motion percept. (C) 1999 Optical Society of America [S0740-3232(99)01701-9].



Bingham, G. P. (1993). “Optical-Flow from Eye-Movement with Head Immobilized - Ocular

Occlusion Beyond the Nose.” Vision Research 33(5-6): 777-789.

The point of observation translates with eye movement because it is not coincident with the

center of rotation in the eye. ''Ocular occlusion'' results. The amount of optical structure

revealed by eye rotation depends on the distances of the occluding and occluded surfaces. The

method of adjustment was used in Expt 1 to investigate the amount of structure detected at

distances up to 1 m. In Expt 2, a forced-choice method was used to confirm predictions based

on the assumption that the point of observation is in the entrance pupil at 11 mm from the

center of rotation. (The location of the point of observation in the eye had not been measured

previously.) Experiment 3 investigated the use of ocular occlusion to detect separation of

surfaces in depth.



Bingushi, K. (1979). “Disappearance and reversal of depth in stereopsis.” Japanese Journal of

Psychology 50(5): 256-264.

Conducted 4 experiments to examine the transition of depth selection by mutual inhibition

among disparities. Results show the following: (a) With random-dot stereograms, the time

required for stereoscopic depth disappearance under fixation was an inverse function of the

magnitude of disparity. (b) Measurement of the cumulative time for perception of ambiguous

stereograms showed that depth was perceived longer with relatively smaller disparity. (c) The

perception of stereoscopic depth under fixation was more stable in random-dot than in

ambiguous target. (d) Stereoscopic depth reversal occurred more frequently under fixation

than in free observation. Results suggest that the whole range of disparities might be detected

simultaneously and that the inhibition mechanism might have an important role in stereopsis.

(19 ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 781 of 887 in

PsycINFO 1978-1984



Bingushi, K. (1980). “Local correspondence and global stereopsis in random-dot stereograms.”

Japanese Journal of Psychology 51(5): 250-258.

Examined the effects of different disparities on global stereopsis by measuring the cumulative

time of stereopsis as an index, using 13 complex ambiguous stereograms. It was found that the

difficulty for stereopsis increased (a) as the number of boundaries between different disparities

increased, (b) as the spatial separation between the boundaries decreased, or (c) as the

difference between the 2 disparities increased. These effects were also studied in relation to

other factors such as noise and magnitude of disparity, which might also be important for

global stereopsis. (17 ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 766 of 887 in PsycINFO 1978-1984



Bingushi, K. and S. Yukumatsu (1984). “Disappearance of Stereopsis in Double-Depth Random-Dot

Stereograms.” Perception 13(1): A37-A37.

Birch, E., D. Birch, et al. (1993). “Breast-Feeding and Optimal Visual Development.” Journal of

Pediatric Ophthalmology & Strabismus 30(1): 33-38.

The goal of the present study was to determine whether dietary supply of omega-3 essential

fatty acid (EFA) influences visual development in healthy pre-term and full-term infants.

Visual status was examined in human milk-fed infants (ample dietary omega-3 EFA supply)

and corn oil-based formula-fed infants (no dietary omega-3 EFA; standard formula prior to

1987). At 57 weeks postconception (4 months adjusted age), both pre-term and full-term

human milk-fed infants had significantly better visual evoked potential (VEP) and forced-

choice preferential-looking (FPL) acuity than formula-fed infants. Acuity was correlated with

a dietary omega-3 sufficiency index from red blood cell membranes obtained at 57 weeks

postconception. At 36 months, full-term human milk-fed children had significantly better

random dot stereo acuity and letter matching ability than formula-fed children. Stereo acuity

and performance on the letter matching test were correlated with a dietary omega-3

sufficiency index from red blood cell membranes obtained at 4 months. These results suggest

that dietary omega-3 fatty acids play an important role in visual development.



Birch, E. and B. Petrig (1996). “FPL and VEP measures of fusion, stereopsis and stereoacuity in

normal infants.” Vision Research 36(9): 1321-1327.

Dynamic random dot fusion, stereopsis and stereoacuity were evaluated in 149 healthy,

fullterm infants, using both forced-choice preferential looking (FPL) and steady-state visual

evoked potential (VEP) protocols. Few infants aged 2-3 months demonstrated fusion or

stereopsis in either the FPL or VEP protocol; most infants aged 5 months and older

demonstrated fusion and stereopsis in both protocols. Both FPL and VEP stereoacuity

approached adult-level (7 degrees generated "default" responses that were independent of the direction of the

step, idiosyncratic, and generally had both horizontal and vertical components. We suggest

that the responses depend on detectors that sense local disparity matches, and that orthogonal

and "default" responses result from globally "false" matches. Recordings from three monkeys,

using identical disparity stimuli, confirmed that monkeys also show short-latency disparity

vergence responses (latency approximate to 25 ms shorter than that of humans), and further

indicated that these responses show all of the major features seen in humans, the differences

between the two species being solely quantitative. Based on these data and those of others

implying that foveal images normally take precedence, we suggest that the mechanisms under

study here ordinarily serve to correct small vergence errors, automatically, especially after

saccades.



Busettini, C., F. A. Miles, et al. (1996). “Short-latency disparity vergence responses and their

dependence on a prior saccadic eye movement.” Journal of Neurophysiology 75(4): 1392-

1410.

1. A dichoptic viewing arrangement was used to study the initial vergence eye movements

elicited by brief horizontal disparity steps applied to large textured patterns in three rhesus

monkeys. Disconjugate steps (range, 0.2-10.9 degrees) were applied to the patterns at selected

times (range, 13-303 ms) after 10 degrees leftward saccades into the center of the pattern. The

horizontal and vertical positions of both eyes were recorded with the electromagnetic search

coil technique.2. Without training or reinforcement, disparity steps of suitable amplitude

consistently elicited vergence responses at short latencies. For example, with 1.8 degrees

crossed-disparity steps applied 26 ms after the centering saccade, the mean latency of onset of

convergence for each of the three monkeys was 52.2 +/- 3.8 (SD) ms, 52.3 +/- 5.2 ms, and

53.4 +/- 4.1 ms.3. Experiments in which the disparity step was confined to only one eye

indicated that each eye was not simply tracking the apparent motion that it saw. For example,

when crossed-disparity steps were confined to the right eye (which saw leftward steps), the

result was (binocular) convergence in which the left eye moved to the right even though that

eye had seen only a stationary scene. This movement of the left eye cannot have resulted from

independent monocular tracking and indicates that the vergence here derived from the

binocular misalignment of the two retinal images.4. The initial vergence responses to crossed-

disparity steps had the following main features. 1) They were always in the correct (i.e.,

convergent) direction over the full range of stimuli tested, the initial vergence acceleration

increasing progressively with increases in disparity until reaching a peak with steps of 1.4-2.4

degrees and declining thereafter to a nonzero asymptote as steps exceeded 5-7 degrees. 2)

They showed transient postsaccadic enhancement whereby steps applied in the immediate

wake of a saccadic eye movement resulted in much higher initial vergence accelerations than

the same steps applied some time later. The response decline in the wake of a saccade was

roughly exponential with time constants of 67 +/- 5 (SD) ms, 35 +/- 2 ms, and 54 +/- 4 ms for

the three animals. 3) That the postsaccadic enhancement might have resulted in part from the

visual stimulation associated with the prior saccade was suggested by the finding that

enhancement could also be observed when the disparity steps were applied in the wake of

(conjugate) saccadelike shifts of the textured pattern. However, this visual enhancement did

not reach a peak until 17-37 ms after the end of the ''simulated'' saccade, and the peak

enhancement averaged only 45% of that after a ''real'' saccade. 4) Qualitatively similar

transient enhancements in the wake of real and simulated saccades have also been reported for

the initial ocular following responses elicited by conjugate drifts of the visual scene. We

replicated the enhancement effects on ocular following to allow a direct comparison with the

enhancement effects on disparity vergence using the same animals and visual stimulus

patterns and, despite some clear quantitative differences, we suggest that the enhancement

effects share a similar etiology.5. Initial vergence responses to uncrossed-disparity steps had

the following main features. 1) They were in the correct (i.e., divergent) direction only for

very small steps ( 0.05). Most cells were band-pass with mean bandwidths of 2.2 and 2.7

octaves for S and C cells, respectively. Enlarging the size of pattern elements yielded an

increase in response amplitude and bandwidth in both cell groups.7. Texture-sensitive units

were distributed in all layers. Strong texture-sensitive C cells were generally located in the

infragranular layers. There was no clear relationship between laminar distribution and noise

responsiveness for S cells.8. Our study shows that, except for response profile and strength,

there were no significant differences between response properties of S and C cells with respect

to their noise sensitivity. These data suggest that visual noise does not allow one to clearly

segregate S from C cells. Also, they do not support the notion that C cells receive inputs not

mediated by S cells.

Casco, C. and M. Morgan (1984). “The relationship between space and time in the perception of

stimuli moving behind a slit.” Perception 13(4): 429-441.

When a shape defined by a set of dots plotted along its contour is presented in a sequence of

frames within the boundaries of a slit, and in each frame only 1 dot (featureless frame) or 2

dots (feature frame) are displayed, a whole moving dotted shape is perceived. Six experiments

were conducted with 2 practiced Ss (the authors) and 2 naive Ss in which masking techniques

and psychophysical measures were used to show that a dynamic random-dot mask interfered

with shape identification, provided that the interframe interval was greater than about 15 msec

and there were no stimulus features for recognition in individual frames. A similar pattern of

results was obtained when the S had only to detect the movement of a single dot or a pair of

dots against a dynamic-noise background. It is concluded that the visual system can resolve

the correspondence problem in both apparent movement (1 moving dot) and aperture viewing

(featureless-frame condition) by extracting motion before the extraction of features in each

frame. However, the results also show that in cases in which feature identification in each

frame is possible, it can also be used to identify the moving targets. (23 ref) (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 685 of 887 in PsycINFO 1978-

1984



Caudek, C. and N. Rubin (2001). “Segmentation in structure from motion: Modeling and

psychophysics.” Vision Research 41(21): 2715-2732.

Designed and tested a psychophysical model for how the human visual system solves the

combined "structure from motion' (SFM; extracting 3-dimensional structure and motion of an

object from 2-dimensional motion information) and segmentation problems, termed SSFM,

concurrently. The model is based on computation of a simple scalar property of the optic flow

field known as def, previously shown to be used by human Os in SFM. The def velocity field

components of many triplets of moving dots were computed, and the identification of multiple

objects in the image was based on detecting multiple peaks in the histogram of def values.

Five experiments were conducted, each with the 1st author and 4 naive undergraduate Os (new

Os for each experiment). Os were presented with random-dot SFM displays that depicted 1 or

2 objects (with or without noise) and were asked to discriminate between the 2 cases. The

results show that human SSFM performance was consistent with the predictions of the model.

The authors compare the predictions of the the model to those of other theoretical approaches,

in particular those that use a rigidity hypothesis, and discuss the validity of each approach as a

model for human SSFM. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 74 of 887 in PsycINFO 2002/01-2002/07



Cavanagh, P. (1995). Is there low-level motion processing for non-luminance-based stimuli? Early

vision and beyond. T. V. Papathomas and C. Chubb. Cambridge, MA, US, The MIT Press:

113-119.

(from the book) Cavanagh's chapter . . . is concerned with the role of attention in detection of

2nd-order motion / much of the modeling of 2nd-order motion . . . proposes that 2nd-order

motion is detected by (1) applying to the input stimulus some grossly nonlinear transformation

(such as linear filtering followed by rectification), and then (2) submitting the transformed

stimulus to spatiotemporal Fourier energy analysis similar to that applied directly to the

(untransformed) stimulus by the short-range motion mechanism in detecting the motion of

random-dot cinematograms / however, an alternative possibility is that such motion is detected

by attentional tracking / Cavanagh uses a variety of empirical methods to investigate this

possibility for a range of different sorts of 2nd-order motion (from the chapter) examine

whether there are specialized low-level motion detectors for non-luminance-based stimuli

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 391 of 887 in

PsycINFO 1993-1995



Cavanagh, P., J. Boeglin, et al. (1985). “Perception of motion in equiluminous kinematograms.”

Perception 14(2): 151-162.

Hypothesized that the interference of the dark interstimulus interval with the motion

perception in kinematograms would be even greater for the relatively weak motion stimulus

provided by an equiluminous presentation. Two of the authors and 2 naive observers served as

Ss. Two fields of random dots that were identical except for a slight shift in a central square

region were presented in rapid alternation, producing a vivid impression of a square moving

back and forth above the background. When the kinematogram was presented in equiluminous

red/green, the motion of the central region was still observed, although over a narrower range

of alternation rates, interstimulus intervals, and displacements than for black/white

presentation. The perception of motion for equiluminous stimuli indicates that color and

motion can be analyzed conjointly by the visual system. However, as reported by V. S.

Ramachandran and R. L. Gregory (see record 1980-11163-001), the segregation of the

oscillating central square from the background is lost at equiluminance. This segregation

process appears to be color-blind. (32 ref) (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 664 of 887 in PsycINFO 1985-1987



Cavanagh, P. and S. Shioiri (1992). “Visual persistence of figures defined by relative motion.” Vision

Research 32(5): 943-951.

Measured

visual persistence (VP) of figures that were solely defined by relative motion (motion-defined figures

[MDFs] or motion figures) in 3 experiments with the author and 4 observers using

random-dot kinematograms. MDFs persisted for about 130 msec after the dots stopped moving,

which was slightly longer than the VP of figures that were defined by a luminance difference

(luminance-defined figures [LDFs] or luminance figures) in the same random-dot pattern. VP is

probably not only a retinal phenomenon but also a cortical one. Coherent movement of the

dots

over the whole display after the stimulus offset did not reduce the VP of motion figures. VP for the

MDFs was longer than that for LDFs independently of the contrast of the stimulus figure as

long as the stimuli could be seen clearly enough. Different mechanisms are most likely involved in

the VP of MDFs and LDFs.



Celebrini, S. and W. T. Newsome (1994). “Neuronal and psychophysical sensitivity to motion signals

in extrastriate area MST of the macaque monkey.” Journal of Neuroscience 14(7): 4109-4124.

Compared the ability of 2 rhesus monkeys and their single medial superior temporal (MST)

neurons to discriminate the direction of motion in a stochastic random dot display. Average

psychophysical and neuronal thresholds, measured on the same trials under precisely identical

conditions, proved to be remarkably similar. Additionally, the slopes of the psychometric and

neurometric functions relating discriminative ability to the strength of the motion signal were

nearly the same on average. Thus, single MST neurons carried motion signals that are well

matched to the psychophysical performance of the Ss. (PsycINFO Database Record (c) 2002

APA, all rights reserved) Record 437 of 887 in PsycINFO 1993-1995



Celebrini, S. and W. T. Newsome (1995). “Microstimulation of Extrastriate Area Mst Influences

Performance on a Direction Discrimination Task.” Journal of Neurophysiology 73(2): 437-

448.

1. Evidence from single-unit recordings suggests that neurons in the medial superior temporal

visual area (MST) carry directional signals that influence psychophysical judgements of

motion direction. We tested this hypothesis by electrically stimulating clusters of directionally

selective neurons in MST (the dorsomedial subdivision, primarily) while rhesus monkeys

performed a two-alternative, forced-choice direction discrimination task.2. We performed

forty-six microstimulation experiments on two rhesus monkeys. The visual stimuli were

dynamic random dot patterns in which the strength of a coherent motion signal could be varied

continuously about psychophysical threshold. The monkeys were rewarded for reporting

correctly the direction of the coherent motion signal. Microstimulation was applied on half the

trials, selected randomly, and the psychophysical data were analyzed to determine whether

stimulation of MST neurons influenced the monkeys' choices.3. Microstimulation influenced

the monkeys' performance in a statistically significant manner in 67% of the experiments. In

all but one of the significant experiments, microstimulation biased the monkeys' choices

toward the direction of motion encoded by MST neurons at the stimulation site.

Microstimulation had little effect on the slopes of the psychometric functions, suggesting that

the stimulation-induced neural activity resembled a relatively pure motion ''signal'' rather than

''noise.''4. Microstimulation exerted strong effects on the monkeys' behavior only when the

visual stimulus was located within the multiunit receptive field measured at the stimulation

site. This kind of spatial specificity has also been observed in the middle temporal visual area

(MT), but receptive fields in MST are typically much larger than those in MT. Thus MST

microstimulation effects are characterized by a coarser spatial scale: stimulation of a single

site in MST can influence judgements over a much larger portion of the visual field than

equivalent stimulation in MT.5. Microstimulation was often most effective when visual

stimuli were placed within a particularly responsive subregion of the receptive field (a ''hot

spot'').6. The results show that MST neurons, like MT neurons, can strongly influence

performance on a direction discrimination task. Whether MT and MST influence the decision

process in parallel or in series remains to be determined.



Celebrini, S., B. Stricanne, et al. (1996). “Neural processing of stereopsis as a function of viewing

distance in primate visual cortical area V1. 700 M 710 Trotter:Yves.” Journal of

Neurophysiology 76(5): 2872-2885.

Investigated how stereoscopic and viewing distance interact in V1, first cortical area where

inputs from each eye are integrated, of 2 behaving monkeys. Cortical cells were recorded

extracellularly in the foveal representation while the Ss performed a fixation tasks. Disparity

selectivity was assessed using static random dot stereograms. Overall results showed that the

neural activity of a large majority of cells in area V1 is modulated by the viewing distance so

that disparity selectivity may be present, or better expressed, at a given viewing distance. The

ongoing activity of about half of the neurons is also modulated, being often significantly

higher at the shortest distance. The finding that visual responsiveness is modulated by viewing

distance in the primary visual cortex indicates that integration of information from retinal and

extraretinal sources can occur early in visual processing pathway for cortical representation of

3-D space. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 293 of 887

in PsycINFO 1996-1997



Chang, J. J. (1986). “Theoretical and methodological approaches to apparent movement of short-range

process and pattern perception.” Behavior Research Methods, Instruments and Computers

18(6): 542-550.

Describes a variable raster and vector display processor interfaced with a PDP-11/23

computer. Several experiments are described that used random-dot cinematograms (raster

displays) and line segments (vector displays) to study apparent motion and attentional effects

in feature discrimination. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 637 of 887 in PsycINFO 1985-1987



Chang, J. J. (1990). “New phenomena linking depth and luminance in stereoscopic motion.” Vision

Research 30(1): 137-147.

Used a novel random-dot stereogram, in which the direction of luminance motion and the

direction of the moving cyclopean (CYC) pattern could be independently controlled, to study

stereoscopic motion in 3 observers. The perceived CYC motion was examined under 5

different conditions, in which the CYC pattern was moving up or down and the luminant dots

were (1) moving in the CYC direction; (2) moving opposite to the CYC direction; (3) moving

orthogonal to the CYC direction; (4) stationary; or (5) dynamic (dots uncorrelated in

successive frames). Luminance direction dominated CYC direction, and smooth and coherent

CYC motion was seen only if luminance motion was present. Results suggest that stereoscopic

motion is processed by interactions between separate binocular disparity units and luminance

motion units. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 569 of

887 in PsycINFO 1990-1992



Chang, J. J. and B. Julesz (1983). “Displacement Limits, Directional Anisotropy and Direction Versus

Form Discrimination in Random-Dot Cinematograms.” Vision Research 23(6): 639-&.



Chang, J. J. and B. Julesz (1983). “Displacement Limits for Spatial-Frequency Filtered Random-Dot

Cinematograms in Apparent Motion.” Vision Research 23(12): 1379-&.



Chang, J. J. and B. Julesz (1984). “Cooperative Phenomena in Apparent Movement Perception of

Random-Dot Cinematograms.” Vision Research 24(12): 1781-1788.



Chang, J. J. and B. Julesz (1985). “Cooperative Process in Depth-Perception of Random-Dot

Stereograms.” Perception 14(1): A21-A21.



Chen, D. and A. Getis (1998). Point Pattern Analysis.

Chen, I. P., S. L. Yeh, et al. (1992). “Motion Capture and Contrast with Spatially Nonoverlapping

Random Dots.” Investigative Ophthalmology & Visual Science 33(4): 1141-1141.



Chen, Y., K. Nakayama, et al. (2003). “Processing of global, but not local, motion direction is deficient

in schizophrenia.” Schizophrenia Research 61(2-3): 215-227.

Visual motion processing is compromised in a substantial proportion of schizophrenic

patients, but precise neural mechanisms underlying the motion-processing deficit have not yet

been elaborated. The visual motion pathway includes a local and a global processing stage,

each of which has distinct neural substrates. Here, we attempt to identify the stage(s) that are

implicated in impaired motion processing of schizophrenia-local, global, or both. For

schizophrenia patients (n = 23) and normal controls (n = 26), we measured (1) the thresholds

for detecting the motion direction of a random dot pattern, a task that requires global motion

processing, and (2) the thresholds for detecting the motion direction of a grating, a task that

requires only local motion processing, using psychophysical methods. Schizophrenia patients

showed elevated thresholds for detecting the direction of coherent motion, particularly for the

high dot-density target. In contrast, schizophrenia patients showed normal thresholds for

detecting the direction of motion of a grating. The results indicate that the global, but not the

local, processing stage of the visual motion system is compromised in schizophrenia patients,

thus implicating motion-sensitive brain areas that possess large receptive fields for spatial and

temporal integration, such as Middle Temporal Area/Medial Superior Temporal Area. (C)

2002 Elsevier Science B.V. All rights reserved.



Chen, Y. Z., Y. J. Wang, et al. (2001). “Modeling V1 disparity tuning to time-varying stimuli.” Journal

of Neurophysiology 86(1): 143-155.

Most models of disparity selectivity consider only the spatial properties of binocular cells.

However, the temporal response is an integral component of real neurons' activities, and time-

varying stimuli are often used in the experiments of disparity tuning. To understand the

temporal dimension of V1 disparity representation, we incorporate a specific temporal

response function into the disparity energy model and demonstrate that the binocular

interaction of complex cells is separable into a Gabor disparity function and a positive time

function. We then investigate how the model simple and complex cells respond to widely used

time-varying stimuli, including motion-in-depth patterns, drifting gratings, moving bars,

moving random-dot stereograms, and dynamic random-dot stereograms. It is found that both

model simple and complex cells show more reliable disparity tuning to time-varying stimuli

than to static stimuli, but similarities in the disparity tuning between simple and complex cells

depend on the stimulus. Specifically, the disparity tuning curves of the two cell types are

similar to each other for either drifting sinusoidal gratings or moving bars. In contrast, when

the stimuli are dynamic random-dot stereograms, the disparity tuning of simple cells is highly

variable, whereas the tuning of complex cells remains reliable. Moreover, cells with similar

motion preferences in the two eyes cannot be truly tuned to motion in depth regardless of the

stimulus types. These simulation results are consistent with a large body of extant

physiological data, and provide some specific, testable predictions.



Cheung, B. S., I. P. Howard, et al. (1991). “Visually-induced sickness in normal and bilaterally

labyrinthine-defective subjects.” Aviation, Space, and Environmental Medicine 62(6): 527-

531.

Exposed a group of 9 Ss (aged 22-59 yrs) with no overt vestibular dysfunction and a group of

6 bilaterally labyrinthine-defective Ss (aged 34-76 yrs) to a visual field rotating about an

Earth-horizontal axis (orthogonal to the gravity axis). The visual stimulus was provided by a

3-m diameter sphere with random dots rotating at 30, 45, and 60|| per second about the

stationary S's roll, pitch, and yaw axes. The S's head was positioned at the center of the sphere

such that it experienced apparent motion in all 3 axes. In the normal group, symptoms of

motion sickness were reported in 21 of 27 trials. When labyrinthine-defective Ss were exposed

to the roll and pitch stimulus, no sickness symptoms were reported or observed. Results

suggest that the vestibular system is necessary for sickness induced by moving visual fields.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 544 of 887 in

PsycINFO 1990-1992

Cheung, B. S. K., I. P. Howard, et al. (1991). “Visually-Induced Sickness in Normal and Bilaterally

Labyrinthine-Defective Subjects.” Aviation Space and Environmental Medicine 62(6): 527-

531.

A group of nine normal subjects (with no overt vestibular dysfunction) and a group of 6

bilaterally labyrinthine-defective subjects were exposed to a visual field rotating about an

Earth-horizontal axis (orthogonal to the gravity axis). The visual stimulus was provided by a

3-m diameter sphere with random dots rotating at 30, 45, and 60 degrees per second

(degrees/s) about the stationary subject's roll, pitch and yaw axes. The subject's head was

positioned at the center of the sphere such that it experienced apparent motion in all three

axes. Results indicated that in the normal group, symptoms of motion sickness were reported

in 21 of 27 test-trials. When labyrinthine-defective subjects were exposed to the roll and pitch

stimulus, no sickness symptoms were reported or observed. These results strongly suggest that

the vestibular system is necessary for sickness induced by moving visual fields.



Chey, J., S. Grossberg, et al. (1997). “Neural dynamics of motion grouping: from aperture ambiguity to

object speed and direction.” Journal of the Optical Society of America a-Optics Image Science

and Vision 14(10): 2570-2594.

A neural network model of visual motion perception and speed discrimination is developed to

simulate data concerning the conditions under which components of moving stimuli cohere or

not into a global direction of motion, as in barberpole and plaid patterns (both type 1 and type

2). The model also simulates how the perceived speed of lines moving in a prescribed

direction depends on their orientation, length, duration, and contrast. Motion direction and

speed both emerge as part of an interactive motion grouping or segmentation process. The

model proposes a solution to the global aperture problem by showing how information from

feature tracking points, namely, locations from which unambiguous motion directions can be

computed, can propagate to ambiguous motion direction points and capture the motion signals

there. The model does this without computing intersections of constraints or parallel Fourier

and non-Fourier pathways. Instead, the model uses orientationally unselective cell responses

to activate directionally tuned transient cells. These transient cells, in turn,activate spatially

short-range filters and competitive mechanisms over multiple spatial scales to generate speed-

tuned and directionally tuned cells. Spatially long-range filters and top-down feedback from

grouping cells are then used to track motion of featural points and to select and propagate

correct motion directions to ambiguous motion points. Top-down grouping can also prime the

system to attend a particular motion direction. The model hereby links low-level automatic

motion processing with attention-based motion processing. Homologs of model mechanisms

have been used in models of other brain systems to simulate data about visual grouping,

figure-ground separation, and speech perception. Earlier versions of the model have simulated

data about short-range and long-range apparent motion, second-order motion, and the effects

of parvocellular and magnocellular lateral geniculate nucleus lesions on motion perception.

(C) 1997 Optical Society of America.



Chey, J., S. Grossberg, et al. (1998). “Neural dynamics of motion processing and speed

discrimination.” Vision Research 38(18): 2769-2786.

A neural network model of visual motion perception and speed discrimination is presented.

The model shows how a distributed population code of speed tuning, that realizes a size-speed

correlation, can be derived from the simplest mechanisms whereby activations of multiple

spatially short-range fillers of different size are transformed into speed-tuned cell responses.

These mechanisms use transient cell responses to moving stimuli? output thresholds that

covary with filter size, and competition. These mechanisms are proposed to occur in the V1 --

> MT cortical processing stream. The model reproduces empirically derived speed

discrimination curves and simulates data showing how visual speed perception and

discrimination can be affected by stimulus contrast, duration, dot density and spatial

frequency. Model motion mechanisms are analogous to mechanisms that have been used to

model 3-D form and figure-ground perception. The model forms the front end of a larger

motion processing system that has been used to simulate how global motion capture occurs,

and how spatial attention is drawn to moving forms. It provides a computational foundation

for an emerging neural theory of 3-D form and motion perception. (C) 1998 Elsevier Science

Ltd. All rights reserved.

Chi, M. T. and D. Klahr (1975). “Span and rate of apprehension in children and adults.” Journal of

Experimental Child Psychology 19(3): 434-439.

In 2 experiments, 12 adults (college students and faculty) and 12 5-6 yr olds quantified

random patterns of dots under unlimited exposure duration. For adults and children 2 distinct

processes appeared to operate. For adults the quantification of collections of from 1 to 3 dots

was essentially errorless and proceeded at the rate of 46 msec/item, while the quantification

rate for from 4 to 10 dots was 307 msec/dot. For children the same operating ranges appeared

to hold, although children were much slower. The lower slope was 195 msec/dot, while the

upper was 1,049. Although the results for adults and children were similar except for the

overall rates, the nature of the isomorphism between children and adults is unclear.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 847 of 887 in

PsycINFO 1967-1977



Chong, S. C. and A. Treisman (2003). “Representation of statistical properties.” Vision Research 43:

393-404.

Everyday scenes often contain sets of similar objects. Perceptual representations may

summarize these with statistical descriptors. After determining the psychological mean of two

sizes, we measured thresholds for judging the mean with arrays of 12 circles of heterogeneous

sizes. They were close to those for the size of elements in homogeneous arrays and single

elements, and were little affected by either exposure duration (50-1000 ms) or memory delays

(up to 2 s). They were only slightly more accurate within the same distribution than across

different distributions (normal, uniform, two-peaks, and homogeneous), confirming that

subjects were indeed averaging sizes.



Christophers, R. A. and B. J. Rogers (1994). “The Effect of Viewing Distance on the Perception of

Complex Random-Dot Stereograms.” Investigative Ophthalmology & Visual Science 35(4):

1624-1624.



Christophers, R. A., B. J. Rogers, et al. (1993). “Perceptual Latencies, Vergence Eye-Movements and

Random Dot Stereograms.” Investigative Ophthalmology & Visual Science 34(4): 1438-1438.



Chubb, C. and G. Sperling (1991). “Texture Quilts - Basic Tools for Studying Motion-from-Texture.”

Journal of Mathematical Psychology 35(4): 411-442.



Chung, C. S. (1983). Form and depth perception in global stereopsis.



Chung, C. S. and K. Berbaum (1984). “Form and depth in global stereopsis.” Journal of Experimental

Psychology: Human Perception and Performance 10(2): 258-275.

Investigated the role of vergence and the relationship between form and depth processes in

global stereopsis in 3 experiments with 47 undergraduates. In Exp I, the speed of stereoscopic

resolution as a function of initial fixation-target distance was measured. In Exp II, accuracy of

discrimination was measured. In Exp III, the speed of resolving random-dot stereograms

(RDSs) in the presence or absence of juxtaposed contoured stereograms (JCSs) was observed.

Results show that performance with JCSs was better than with the RDSs in speed and

accuracy. In RDSs, vergence played a role in solution; discrimination of forms was

independent of and more accurate than discrimination of depth; and the disparity of target

relative to fixation systematically affected discrimination of form. Strong interference with the

solution of the RDS by the monocular contour occurred when the 2 types of stimuli were

present simultaneously. (60 ref) (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 705 of 887 in PsycINFO 1978-1984



Ciner, E., L. Cyert, et al. (2003). “Testability of preschoolers on stereotests used to screen vision

disorders.” Optometry and Vision Science 80(11): 753-757.

Objective. The purpose was to determine whether preschool children aged 3 years 0 months

through 3 years 6 months could be tested with the Random Dot E, Stereo Smile, and Randot

Preschool stereoacuity tests, which are random dot stereotests marketed for use with

preschoolers. Methods. A total of 118 children from five Vision In Preschoolers Study

Clinical Centers participated. Strabismic children, as determined by the cover test at distance

and near, were excluded from this study. Stereopsis was tested on each child using each of the

three tests in a variable, balanced order. A child's testability for each test was determined by

the ability to complete the nonstereo task (pretest) and the gross stereo task for each stereotest.

Proportions of children able to perform each test were compared using statistical methods

accommodating multiple measurements per child. Results. Testability of children on the

pretest was greater for the Stereo Smile test (91%) than for the Random Dot E test (81%; p =

0.007) or the Randot Preschool test (71%; p 0.12, all comparisons). Conclusions. Among preschoolers aged 3

years 0 months through 3 years 6 months, testability differs significantly across the three

commercially available random dot stereotests evaluated. The results suggest that two-choice

procedures increase testability of young preschoolers.



Ciner, E. B., E. SchanelKlitsch, et al. (1996). “Stereoacuity development: 6 months to 5 years. A new

tool for testing and screening.” Optometry and Vision Science 73(1): 43-48.

A new tool to measure changes in random dot stereoacuity development from 6 months to 5

years of age was developed and tested. Either a forced choice or operant preferential looking

(PL) paradigm with a happy face target was successfully used to test 136 children. Results

indicate that stereoacuity measurements continue to develop through the first years of life.

Although children below 24 months of age can be expected to have stereo thresholds in the

range of 300 sec are, there is a transition at approximately 24 months of age after which

stereoacuity approaches adult levels. The sensitivity of this test in detecting binocular vision

problems was 80%. These results provide guidelines for the assessment of stereoacuity in

young children and also provide a new tool for the early detection of binocular vision

anomalies.



Ciner, E. B., E. Schanelklitsch, et al. (1991). “Stereoacuity Development in Young-Children.”

Optometry and Vision Science 68(7): 533-536.

An operant preferential looking (OPL) test with random dot stereo targets was used to gather

developmental data on stereoacuity thresholds in 180 children between 18 and 65 months of

age. Results indicated a steady improvement in stereoacuity with age from 250 sec arc in the

youngest children tested to 60 sec arc in the oldest group of children. The greatest

improvement in stereoacuity occurs at 30 months of age where mean values improve from 225

to 125 sec arc. This large change in stereo threshold appears to be attributable to the

significantly higher variability in responses in the children under 30 months of age vs. the

lower variability in responses in children over 30 months of age. The overall steady

improvements in stereoacuity appear to be a result of the developmental changes in the

variability of responses rather than actual neurophysiological changes within the visual

system.



Ciner, E. B., P. P. Schmidt, et al. (1998). “Vision screening of preschool children: Evaluating the past,

looking toward the future.” Optometry and Vision Science 75(8): 571-584.

Vision problems of preschool children are detectable with a comprehensive eye examination;

however, it is estimated that only 14% of children below the age of 6 years receive an eye

examination. Screening is advocated as a cost-effective alternative to identify children in need

of further vision care. Thirty-four states recommend or require vision screening of preschool

children. Although laws and guidelines exist, only 21% of preschool children are actually

screened for vision problems. There is little agreement concerning the best screening methods,

and no validated, highly effective model for screening vision of preschool children. Newer

screening tests have been designed specifically for preschool populations, and can be

administered by lay screeners. Many have not been validated. Several are recommended by

states or organizations without convincing scientific evidence of their effectiveness. This

paper summarizes current laws and guidelines for preschool vision screening in the United

States, reviews advantages and disadvantages of several test procedures, and provides

recommendations for developing future preschool vision screening programs.



Cleary, R. (1990). “Contrast dependence of short-range apparent motion.” Vision Research 30(3): 463-

478.

Assessed the apparent motion (APMO) of band-pass filtered random dot kinematograms by

measurements of 2 alternative direction discrimination performances. In the case of 2-

dimensional stimuli, results were independent of contrast. However, for 1-dimensional

(grating) stimuli, APMO seemed to depend on contrast. The breakdown of APMO is

interpreted as a decreased signal-to-noise ratio in the pooled response of motion detectors that

tend to contrast saturation. "Noise" refers to the sampling components present in any APMO

sequence. The discrepancy between results from 1- and 2-dimensional stimuli suggests that

motion is initially encoded by orientationally tuned mechanisms. (PsycINFO Database Record

(c) 2002 APA, all rights reserved) Record 568 of 887 in PsycINFO 1990-1992



Cleary, R. and O. J. Braddick (1990). “Direction Discrimination for Band-Pass Filtered Random Dot

Kinematograms.” Vision Research 30(2): 303-&.



Cleary, R. and O. J. Braddick (1990). “Masking of low frequency information in short-range apparent

motion.” Vision Research 30(2): 317-327.

Examined the masking of low spatial frequency information within the short range process,

using spatially low-pass filtered random dot kinematograms. Three observers were presented

with a set of kinematograms in which the upper cut-off frequency of the stimulus (F-sub(h))

was constant and stimulus displacement was varied. Ss reported the direction of apparent

motion. Results show that the upper limit, d-sub(max ) was dependent on F-sub(h), which in

turn depended on the size of the stimulus. Data suggest a process whereby low spatial

frequency motion information is masked by the presence of high spatial frequencies in the

same region of the field, analogous to phenomena occurring in the perception of static form.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 572 of 887 in

PsycINFO 1988-1989



Cleveland, W. S. and R. Guarino (1978). “The use of numerical and graphical statistical methods in the

analysis of data on learning to see complex random-dot stereograms.” Perception 7(1): 113-

118.

Several numerical and graphical statistical methods are illustrated in an analysis of data from

an experiment (J. P. Frisby and J. L. Clatworthy; see record 1976-06036-001) that investigated

a hypothesis of B. Julesz (1971) that giving a person a priori information about the structure of

a complex random-dot stereogram reduces the time needed to perceive it when it is viewed.

The data are divided into 2 groups, one consisting of those observers who received no cue or

verbal cues (NV) and the other consisting of those who received verbal-visual cues (VV). A

quantile-quantile plot shows that the NV times were longer than the VV times. By using

probability plots, it is shown that the perception times have an exponential probability

distribution. A hypothesis test based upon this distribution is used to show that the differences

between the NV and VV were significant slightly below the 0.05 level. (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 812 of 887 in PsycINFO 1967-1977



Clifford, C. W. G., S. A. Beardsley, et al. (1999). “The perception and discrimination of speed in

complex motion.” Vision Research 39(13): 2213-2227.

Random dot kinematograms were used to simulate radial, rotational and spiral optic flow. The

stimuli were designed so that, while dot speed increased linearly with distance from the centre

of the display, the density of dots remained uniform throughout their presentation. In two

experiments, subjects were required to perform a temporal 2AFC speed discrimination task.

Experiment 1 measured the perceived speed of a range of optic flow patterns against a

rotational comparison stimulus. Radial motions were found to appear faster than rotations by

approximately 10%, with a smaller but significant effect for spirals. Experiment 2 measured

discrimination thresholds for pairs of similar optic flow stimuli identical in all respects except

mean speed. No consistent differences were observed between the speed discrimination

thresholds of radial, rotational and spiral motions and a control stimulus with the same speed

profile in which motion followed fixed random trajectories. The perceived speed results are

interpreted in terms of a model satisfying constraints on motion-in-depth and object rigidity,

while speed discrimination appears to be based upon the pooled responses of elementary

motion detectors. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.



Cobo Lewis, A. B. (1993). A psychophysical investigation of mechanisms selective for the spatial

frequency of disparity modulation in random-dot stereograms.

Cobo Lewis, A. B. (1996). “Monocular dot-density cues in random-dot sterograms.” Vision Research

36(3): 345-350.

Describes the nature of the density cues introduced by the projection method for constructing

random dot stereograms by deriving them mathematically. S. C. de Vries et al (see record

80:08167) proposed to minimize the density cues by selecting half of the random dots from a

uniform random distribution in the right-eye image, projecting them onto the cyclopean

surface, and then projecting them back to the left-eye image and vice versa. It is shown that

the projection method and the modification introduced by de Vries et al have very similar

density cues near the medial sagittal plan when polar projection is employed and that they

have identical density cues over the entire random-dot field when parallel projection is

employed. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 352 of 887

in PsycINFO 1996-1997



CoboLewis, A. B. (1996). “Monocular dot-density cues in random-dot stereograms.” Vision Research

36(3): 345-350.

In the original random-dot stereograms (RDSs) invented by Julesz, binocular disparity could

only take on values that were integral multiples of dot width. The other common method for

constructing RDSs (the projection method) relaxes this restriction, However, the projection

method can introduce dot-density cues into the monocular images, When polar projection is

employed, density variation is introduced as an expression of perspective cues; when parallel

projection is employed, there are no perspective cues, but density variation is nonetheless

introduced whenever disparity varies as a function of horizontal position. de Vries, Kappers,

and Koenderink [(1994) Vision Research, 34, 2409-2423] proposed to minimize the density

cues by selecting half of the random dots from a uniform random distribution in the right-eye

image, projecting them onto the cyclopean surface, and then projecting them back to the left

eye image and vice versa, In this paper the precise nature of the density cues introduced by the

projection method, and by de Vries et al.'s modification of that method, are derived. It is also

shown that the projection method and its modification have very similar density cues near the

medial sagittal plane when polar projection is employed, and that they have identical density

cues over the entire random-dot field when parallel projection is employed.



Cobolewis, A. B., S. C. Panish, et al. (1995). “Monocular Dot-Density Cues in Random-Dot

Stereograms.” Investigative Ophthalmology & Visual Science 36(4): S364-S364.



Cobolewis, A. B. and Y. Y. Yeh (1992). “Adaptation Aftereffects Following Viewing of Rotating

Random-Dot Stereoscopic Spheres.” Investigative Ophthalmology & Visual Science 33(4):

1374-1374.



Cogan, A. I., A. J. Lomakin, et al. (1993). “Depth in Anticorrelated Stereograms - Effects of Spatial

Density and Interocular Delay.” Vision Research 33(14): 1959-1975.

Disparity-based depth is not perceived in densely textured, anticorrelated random-dot

stereograms (RDSs) whose elements carry opposite signs of brightness contrast on

corresponding loci, as extant data show. We observed global depth in anticorrelated RDSs

flashed repetitively with an interocular delay. During the delay time, a dot array in one eye

was paired with a gray frame in the other eye and thus could interact with the negative

afterimage of the contralateral dot array. A correlated RDS (e.g. 8 min arc dots, 50% density,

15-msec flash duration) lost depth with delays > 45 msec. An anticorrelated RDS, that was

otherwise identical, showed robust depth when flashed with an interocular delay of some 60

msec. A delay was not always necessary to produce depth. At low dot density (1-2%),

anticorrelated RDSs showed disparity-dependent local depth even when displayed

continuously, or flashed simultaneously; as dot density alone was increased, depth was

progressively lost. To make global depth visible in a dense RDS flashed with an interocular

delay, the internal response had to be strongly biphasic. Our results support the generally held

notion that cyclopean depth signals emerge exclusively from same-sign binocular cortical

filters. However, the exclusionary rule may be invalid with respect to the processing of coarse

local depth with figural stimuli. Relative depth between a pair of small dots was easily

perceived when one of the dots was in opposite contrast, but the depth threshold was then

about 0.5 log unit higher than with the same-contrast pair of dots indicating that the internal

effects of contrast have not all lost their sign prior to binocular disparity processing. It remains

to be determined whether depth can be perceived from edges of opposite contrast.



Cogan, A. I., A. J. Lomakin, et al. (1993). “Depth in anticorrelated stereograms: Effects of spatial

density and interocular delay.” Vision Research 33(14): 1959-1975.

Observed global depth in anticorrelated random dot stereograms (RDSs) flashed repetitively

with an interocular delay. During the delay time, a dot array in one eye was paired with a gray

frame in the other eye and thus could interact with the negative afterimage of the contralateral

dot array. A correlated RDS lost depth with delays >45 msec. An anticorrelated RDS that was

otherwise identical showed robust depth when flashed with an interocular delay of 60 msec. A

delay was not always necessary to produce depth. At low dot density, anticorrelated RDSs

showed disparity-dependent local depth even when displayed continuously, or flashed

simultaneously; as dot density alone was increased, depth was progressively lost. To make

global depth visible in a dense RDS flashed with an interocular delay, the internal response

had to be strongly biphasic. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 475 of 887 in PsycINFO 1993-1995



Cohene, L. S. and H. P. Bechtoldt (1974). “Some temporal factors in visual pattern recognition: II.”

Proceedings of the Iowa Academy of Science(81): 111-115.

Pairs of random dot patterns in which the patterns of each pair formed bigrams when

superimposed were used to investigate the hypothesis that the temporal integration of visual

patterns reported by C. W. Eriksen could be extended toward the longer time scale used in

studies of eidetic imagery. An integration theory suggests that when the dot pattern stimuli are

temporally separated, the neural trace arising from the 1st pattern must be combined with the

2nd pattern for a verbal recognition to occur. However, the unexpected results of the present 3

experiments with a total of 98 undergraduates indicate that a 1st dot pattern of 1-, 3-, or 5.4-

sec duration was not integrated with a complementary 2nd dot pattern of 2 sec unless the pair

of patterns were overlapped in time. The duration of the overlapped exposure times required

for recognition was 5-8 times longer than the time required for recognition with simultaneous

onset and offset of the same dot patterns. Suggestions as to the source of the serious

interfering or masking effect in the integration process are discussed. (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 846 of 887 in PsycINFO 1967-1977



Compton, B. J. and G. D. Logan (1993). “Evaluating a Computational Model of Perceptual Grouping

by Proximity.” Perception & Psychophysics 53(4): 403-421.

A formal approach to the phenomenon of perceptual grouping by proximity was investigated.

Grouping judgments of random dot patterns were made by the CODE algorithm (van Oeffelen

& Vos, 1982) and several related algorithms, and these judgments were compared with

subjects' grouping judgments for the same stimuli. Each algorithm predicted significantly

more subject judgments than would be expected by chance. The more subjects agreed on how

a given dot pattern should be grouped, the more successful was the algorithms' ability to

match the judgments for that pattern. CODE predicted significantly fewer subject judgments

than did some of the other algorithms, largely because of its overemphasis on the extent of

interactivity among dots as they are being grouped.



Compton, B. J. and G. D. Logan (1999). “Judgments of perceptual groups: Reliability and sensitivity to

stimulus transformation.” Perception & Psychophysics 61(7): 1320-1335.

The reliability of subjects' judgments of the groups present in dot patterns and the sensitivity

of those judgments to stimulus transformation were assessed. The subjects indicated the

groups that they saw within random dot patterns, and each judgment was compared with those

of other subjects and with their own judgments for related presentations. Within subjects, each

pattern appeared in an initial presentation, an identical repetition, and a transformed state (a

rotation or a change in scale), Within-subjects judgments were more reliable than between-

subjects judgments, An interpretation of within-subjects results was made in relation to

predictions made by a formal algorithm of grouping by proximity (the CODE algorithm),

which assumes that grouping by proximity is invariant over transformations such as rotations

or changes in scale. A slight cost to transforming the patterns was found. The implications for

CODE and for using grouping judgments as data are discussed.

Cooper, J. and J. Feldman (1980). “Operant-Conditioning of Fusional Convergence Ranges Using

Random Dot Stereograms.” American Journal of Optometry and Physiological Optics 57(4):

204-213.



Cornelissen, F. W. and A. C. Kooijman (1991). “Influence of Blur, Eccentricity, Luminance, and

Contrast on the Visibility of Density-Modulated Random Dot Patterns.” Perception 20(1):

121-121.



Cornelissen, F. W. and A. C. Kooijman (1994). “Interactions between Modulated Luminance Patterns

and Random-Dot Patterns.” Vision Research 34(19): 2561-2568.

It has been suggested that density modulated random-dot patterns can be used to study higher

order pattern vision [Van Meeteren and Barlow (1981) Vision Research, 21, 765-777]. The

high contrast dots of which the pattern is composed, are assumed to be reliably transduced-and

transmitted by the lower levels of the visual system. Therefore, such dot patterns could offer a

way of by-passing the limits set by these earlier steps in the visual system. So, detection

performance should reflect the capacity of more central visual mechanisms to combine and

compare groups of dots. We test this assumption by selectively desensitizing the spatial

frequency channels which are involved in detecting luminance contrast patterns. The results

show a selective decrease in sensitivity for modulations in dot density at the adapting spatial

frequency. We conclude that detection of differences in dot density is mediated by the same

channels that detect luminance contrast. The conclusion by Van Meeteren and Barlow that dot

patterns can be used to study higher order processing in the visual system appears not to be

valid. In addition, we present a new type of modulated dot pattern of which the density

modulations are shown to be invisible for the spatial frequency channels. This pattern may

therefore be used to study higher order visual processing.



Cornelissen, F. W., A. C. Kooijman, et al. (1992). “Binocular Combination of Density Modulated

Random Dot Patterns.” Investigative Ophthalmology & Visual Science 33(4): 1374-1374.



Cornette, L., P. Dupont, et al. (1998). “Human brain regions involved in direction discrimination.”

Journal of Neurophysiology 79(5): 2749-2765.

To obtain further evidence for the functional specialization and task-dependent processing in

the human visual system, we used positron emission tomography to compare regional cerebral

blood flow in two direction discrimination tasks and four control tasks. The stimulus

configuration, which was identical in all tasks, included the motion of a random dot pattern,

dimming of a fixation point, and a tone burst. The discrimination tasks comprised the

identification of motion direction and successive direction discrimination. The control tasks

were motion detection, dimming detection, tone detection, and passive viewing. There was

little difference in the activation patterns evoked by the three detection tasks except for

decreased activity in the parietal cortex during the detection of a tone. Thus attention to a

nonvisual stimulus modulated different visual cortical regions nonuniformly. Comparison of

successive discrimination with motion detection yielded significant activation in the right

fusiform gyrus, right lingual gyrus, right frontal operculum, left inferior frontal gyrus, and

right thalamus. The fusiform and opercular activation sites persisted even after subtracting

direction identification from successive discrimination, indicating their involvement in

temporal comparison. Functional magnetic resonance imaging (fMRI) experiments confirmed

the weak nature of the activation of human MT/V5 by successive direction discrimination but

also indicated the involvement of an inferior satellite of human MT/V5. The fMRI

experiments moreover confirmed the involvement of human V3A, lingual, and parietal regions

in successive discrimination. Our results provide further evidence for the functional

specialization of the human visual system because the cortical regions involved in direction

discrimination partially differ from those involved in orientation discrimination. They also

support the principle of task-dependent visual processing and indicate that the right fusiform

gyrus participates in temporal comparison, irrespective of the stimulus attribute.



Cornette, L., P. Dupont, et al. (1998). “Human cerebral activity evoked by motion reversal and motion

onset - A PET study.” Brain 121: 143-157.

In this PET study, we have investigated the human brain activity evoked by a visual motion

paradigm commonly used to measure motion-related visual evoked potentials (VEPs).

Because standard PET activation studies have been performed with motion along four axes,

we first determined the pattern of brain activation when motion was restricted to a single axis.

Motion back and forward along a single horizontal axis compared with a static condition

revealed weak differential activations in the cuneus and the parietal cortex. Human area

MT/V5 (middle temporal area) was hardly activated at all in this subtraction. Additional

functional MRI experiments proved that MT/V5 activity is significantly higher for motion

along four axes than for motion along a single axis. Secondly we attempted to isolate the

pattern of brain activity related to the reversal of motion direction and to the onset of motion,

i.e. two transient motion components commonly used in measuring motion-related VEPs. To

that end, we added a continuous linear contrast modulation, that reached maximum contrast at

reversal or onset of motion, and compared both conditions with a cingulate cortex. Although

the significance of this activation is unclear it adds further evidence for the visual function of

this region. contrast-modulated static or continuous motion condition. Subtraction of the static

random dot pattern condition from the single-axis motion reversal condition, both contrast-

modulated revealed three significant activations: the anterior parieto-occipital sulcus, the

lateral sulcus and the anterior claustrum. Additional analysis showed that these activations

were not due to motion appearance or disappearance, but were due to the combination of

motion reversal and contrast modulation. Hence, these activations do not reflect the motion

reversal transient per se. In order to isolate a metabolic response to the reversal transient per

se, we used a conjunction analysis, which suggests that activity in human MT/V5, the cuneus

and a parietal insular region could underlie the motion reversal VEP in our experiments.

Subtraction of the static random dot pattern conditions from the single-axis motion onset

condition, both contrast-modulated revealed a single significant activation in the posterior

cingulate cortex. Although the significance of this activation is unclear, it adds further

evidence for the visual function of this region.



Costa, T. and G. Pravettoni (1995). “Analisi dell'illusione di Poggendorff con textures casuali. / The

analysis of the Poggendorff effect as a function of random dot textures.” Ricerche di

Psicologia 19(3): 71-79.

Studied the influence of retinal factors, observer distance, and the strength of the Poggendorff

illusion depicted with different densities of random dots in the vertical portion of the illusion.

Human Ss: 15 normal Italian persons. Ss were seated 1.5 m from a computer screen and

presented with a series of Poggendorff illusions that differed in the alignment of left and right

oblique lines and pixel density between vertical line segments. Ss were asked to move the

right oblique line and align it with the left oblique line. Each Ss completed 20 trials under 9

conditions of pixel density. The results were evaluated according to degree of alignment

errors, measured in mm, and pixel density. Statistical tests were used. (English abstract)

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 356 of 887 in

PsycINFO 1993-1995



Cowey, A., A. M. Parkinson, et al. (1975). “Global stereopsis in rhesus monkeys.” Quarterly Journal of

Experimental Psychology 27(1): 93-109.

In 3 separate experiments an attempt was made to demonstrate global stereopsis in 2 rhesus

monkeys by using random dot stereograms projected and viewed through polarizing filters.

Although both Ss learned a number of discriminations, control tests showed that both were

perceiving nondepth cues such as monocular identification of minute pattern differences or

brightness differences caused by reflections of polarized light. In a final experiment, red-green

anaglyph forms of the stereograms were viewed through red-green filters. Both Ss, together

with a 3rd experimentally naive animal, showed incontrovertible evidence of prompt

discrimination based on stereopsis. Recommendations about the use of random dot

stereograms to demonstrate global stereopsis in animals are presented. (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 848 of 887 in PsycINFO 1967-1977



Crawford, M. L. J., R. S. Harwerth, et al. (1996). “Binocularity in prism-reared monkeys.” Eye 10:

161-166.

Prismatic binocular dissociation in infant monkeys mimicked a concomitant squint. Within 3

weeks, the numbers of binocular neurons in the primary visual cortex were reduced by half

and did not recover with up to 5 years of subsequent unrestricted binocular visual experience.

The monkeys failed to show binocular summation for spatial contrast sensitivity tasks and

were unable to utilise horizontal binocular disparities in random-dot stereograms - two indices

of stereoblindness. Electrophysiological analysis of the V1 and V2 cortices showed a dramatic

reduction in binocular neurons. Analysis of interocular spatial phase tuning functions showed

a conspicuous loss of excitatory binocular drive in V1 neurons which was sufficient to account

for many of the defects in binocular function.



Crawford, M. L. J., R. S. Harwerth, et al. (1996). “Loss of stereopsis in monkeys following prismatic

binocular dissociation during infancy.” Behavioural Brain Research 79(1-2): 207-218.

Prismatic binocular dissociation was used during infancy to mimic conditions of strabismus in

macaque infants. Prisms worn continuously produce a diplopia unfavorable for the

maintenance and development of the binocular visual system. Prism-reared monkeys were

tested as young adults and found to be permanently stereoblind for dynamic random dot

stereograms. Control monkeys did comparably to humans on such tests. It is concluded that

short periods of diplopia attendant with strabismus are sufficient to produce permanent

stereoblindness. (PsycINFO Database Record (c) 2002 APA, all rights reserved)(journal

abstract) Record 331 of 887 in PsycINFO 1996-1997



Crawford, M. L. J., R. S. Harwerth, et al. (1996). “Loss of stereopsis in monkeys following prismatic

binocular dissociation during infancy.” Behavioural Brain Research 79(1-2): 207-218.

Prismatic binocular dissociation was used during infancy to mimic conditions of strabismus in

macaque infants. Prisms worn continuously produce a diplopia unfavorable for the

maintenance and development of the binocular visual system. Prism-reared monkeys were

tested as young adults and found to be permanently stereoblind for dynamic random dot

stereograms. Control monkeys did comparably to humans on such tests. It is concluded that

short periods of diplopia attendant with strabismus are sufficient to produce permanent

stereoblindness.



Crawford, M. L. J., T. W. Pesch, et al. (1996). “Excitatory binocular neurons are lost following

prismatic binocular dissociation in infant monkeys.” Behavioural Brain Research 79(1-2):

227-232.

Four infant rhesus monkeys had prismatic dissociation of binocular vision by viewing the

world through prisms. Those monkeys tested previously for ability to utilize horizontal

disparity cues in detection of dynamic random dot stereograms were found here to have few

excitatory binocular neurons in visual cortex (V1). Each eye was well represented in the

monocular ability to drive cortical neurons, while stimulus orientation tuning appeared normal

in the monocular neurons, but somewhat less sensitive in the remaining binocular neurons.

Binocular dissociation early in life constitutes conditions unfavorable for the maintenance of

neural connections delivering binocular excitation to the visual cortex. (PsycINFO Database

Record (c) 2002 APA, all rights reserved)(journal abstract) Record 329 of 887 in PsycINFO

1996-1997



Crawford, M. L. J., T. W. Pesch, et al. (1996). “Excitatory binocular neurons are lost following

prismatic binocular dissociation in infant monkeys.” Behavioural Brain Research 79(1-2):

227-232.

Four infant rhesus monkeys had prismatic dissociation of binocular vision by viewing the

world through prisms. Those monkeys tested previously for ability to utilize horizontal

disparity cues in detection of dynamic random dot stereograms, were found here to have few

excitatory binocular neurons in visual cortex (V1). Each eye was well represented in the

monocular ability to drive cortical neurons, whilst stimulus orientation tuning appeared

normal in the monocular neurons, but somewhat less sensitive in the remaining binocular

neurons. Binocular dissociation early in life constitutes conditions unfavorable for the

maintenance of neural connections delivering binocular excitation to the visual cortex.



Crawford, M. L. J., G. K. von Noorden, et al. (1996). “Judgments by monkeys of apparent depth in

dynamic random-dot stereograms.” Behavioural Brain Research 79(1-2): 219-225.

Young macaques discriminated apparent depths of targets embedded in dynamic random dot

stereograms; a test of stereopsis. In a 'same/different' paradigm, the discrimination took longer

if the pair of stimuli appeared to be in same depth plane, than when they appeared to be

located in a different depth plane. The decision time was an inverse function of the disparity

difference. Apparent depth discrimination performance decreased as a function of disparity,

with no differences in judgments regarding crossed or uncrossed disparities. (PsycINFO

Database Record (c) 2002 APA, all rights reserved)(journal abstract) Record 330 of 887 in

PsycINFO 1996-1997



Crawford, M. L. J., G. K. vonNoorden, et al. (1996). “Judgments by monkeys of apparent depth in

dynamic random-dot stereograms.” Behavioural Brain Research 79(1-2): 219-225.

Young macaques discriminated apparent depths of targets embedded in dynamic random dot

stereograms; a test of stereopsis. In a 'same/different' paradigm, the discrimination took longer

if the pair of stimuli appeared to be in same depth plane, than when they appeared to be

located in a different depth plane. The decision time was an inverse function of the disparity

difference. Apparent depth discrimination performance decreased as a function of disparity,

with no differences in judgments regarding crossed or uncrossed disparities.



Croner, L. J. and T. D. Albright (1997). “Image segmentation enhances discrimination of motion in

visual noise.” Vision Research 37(11): 1415-1427.

The primate visual system uses form cues-such as hue, contrast polarity,luminance, and

texture-to segment complex retinal images into the constituent objects of the visual scene. We

investigated whether segmentation of dynamic images on the basis of hue, luminance contrast

polarity, or luminance contrast amplitude aids discrimination of motion direction. Human

subjects viewed dynamic displays of randomly positioned dots, in which a variable proportion

of the dots moved in the same direction at the same speed (''signal'' dots) while the remaining

dots were randomly displaced (''noise'' dots). In agreement with previous reports, we observed

a reliable relationship between the strength of the motion signal and subjects' ability to

discriminate motion direction, enabling the measurement of thresholds for direction

discrimination. When signal dots had a different luminance contrast amplitude than noise dots,

direction discrimination performance was directly related to the relative contrast of the signal

dots, demonstrating the importance of matching the perceived contrast amplitude of signal and

noise tokens when testing the effects of segmentation by other cues. When Michelson

luminance contrast was matched, distinguishing signal from noise dots by hue or by

luminance contrast polarity strongly improved direction discrimination, lowering thresholds

by an average factor of five. These results reveal a strong influence of form cues on motion

processing in the human visual system, and suggest that segmentation on the basis of form

cues occurs prior to motion processing. (C) 1997 Elsevier Science Ltd.



Cropper, S. J., D. R. Badcock, et al. (1994). “On the Role of 2nd-Order Signals in the Perceived

Direction of Motion of Type-Ii Plaid Patterns.” Vision Research 34(19): 2609-2612.

Second-order Type I and Type II plaids were constructed by combining two random-dot

gratings. Each component consisted of a dynamic random-dot field, the contrast of which was

modulated by a drifting sinusoidal grating. Orienting the two components suitably and

interleaving at 120 Hz allowed us to produce a two-dimensional plaid pattern made from one-

dimensional second-order components. The perceived direction of motion of both Type I and

Type II plaids was measured as a function of stimulus duration. Type I plaids had a perceived

direction close to the intersection of constraints/vector sum solution (which only coincide for

these patterns) at all durations. Type II plaids had a perceived direction that moved away from

the vector sum and toward the intersection of constraints solution as the duration of

presentation increased. These results are similar in form to those found for plaids made from

first-order (luminance-defined) components [Yo & Wilson (1992), Vision Research, 32, 135-

147]. This suggests that a delay which operates specifically on second-order signals cannot be

the sole cause for the change in perceived direction of Type II plaids made from first-order

components [Wilson, Ferrera and Yo (1992), Visual Neuroscience, 9,79-97].



Crowell, J. A. and R. A. Andersen (2001). “Pursuit compensation during self-motion.” Perception

30(12): 1465-1488.

The pattern of motion in the retinal image during self-motion contains information about the

person's movement. Pursuit eye movements perturb the pattern of retinal-image motion,

complicating the problem of self-motion perception. A question of considerable current

interest is the relative importance of retinal and extra-retinal signals in compensating for these

effects of pursuit on the retinal image. We addressed this question by examining the effect of

prior motion stimuli on self-motion judgments during pursuit. Observers viewed 300 ms

random-dot displays simulating forward self-motion during pursuit to the right or to the left; at

the end of each display a probe appeared and observers judged whether they would pass left or

right of it. The display was preceded by a 300 ms dot pattern that was either stationary or

moved in the same direction as, or opposite to, the eye movement. This prior motion stimulus

had a large effect on self-motion judgments when the simulated scene was a frontoparallel

wall (experiment 1), but not when it was a three-dimensional (3-D) scene (experiment 2).

Corresponding simulated-pursuit conditions controlled for purely retinal motion aftereffects,

implying that the effect in experiment 1 is mediated by an interaction between retinal and

extra-retinal signals. In experiment 3, we examined self-motion judgments with respect to a 3-

D scene with mixtures of real and simulated pursuit. When real and simulated pursuits were in

opposite directions, performance was determined by the total amount of pursuit-related retinal

motion, consistent with an extra-retinal 'trigger' signal that facilitates the action of a retinally

based pursuit-compensation mechanism. However, results of experiment 1 without a prior

motion stimulus imply that extra-retinal signals are more informative when retinal information

is lacking. We conclude that the relative importance of retinal and extra-retinal signals for

pursuit compensation varies with the informativeness of the retinal motion pattern, at least for

short durations. Our results provide partial explanations for a number of findings in the

literature on perception of self-motion and motion in the frontal plane.



Crowell, J. A. and M. S. Banks (1996). “Ideal observer for heading judgments.” Vision Research 36(3):

471-490.

Several aspects of the viewing situation affect the ability to determine heading from optical

flow, These include the amount of depth variation and number of texture elements in the

scene, the location and amount of the visual field stimulated, and the position of the focus of

expansion within the stimulus. Without a quantification of the discrimination information

provided by the stimuli presented to the observer, it is impossible to determine how much of

an observed change in performance reflects the properties of neural mechanisms and strategies

employed by the observer. To enable a better quantification, we developed an ideal observer

for the discrimination of heading from random-dot bow fields, Internal noises of the ideal

observer were set by the results of single-dot velocity discrimination experiments, We

compared human and ideal observer performance in discriminating headings with different

patterns of flow (e.g. radial vs laminar) presented on different parts of the retina, Efficiency-

the ratio of ideal and human thresholds-was fairly constant for the various flow patterns and

retinal eccentricities, This outcome indicates that most of the variation in human observers'

ability to estimate heading from the flow patterns and retinal loci considered here is due to

changes in the discrimination information provided by the stimulus after measurement by the

visual system, In the discussion, we show how the ideal observer can be used to quantify the

spatial distribution of heading discrimination information for any observer translation through

any scene represented by dots.



Cumming, B. G. (1995). “The Relationship between Stereoacuity and Stereomotion Thresholds.”

Perception 24(1): 105-114.

There are in principle at least two binocular sources of information that could be used to

determine the motion of an object towards or away from an observer; such motion produces

changes in binocular disparities over time and also generates different image velocities in the

two eyes. It has been argued in the past that stereomotion is detected by a mechanism that is

independent of that which detects static disparities. More recently this conclusion has been

questioned. If stereomotion detection in fact depends upon detecting disparities, there should

be a clear correlation between static stereo-detection thresholds and stereomotion thresholds.

If the systems are separate, there need be no such correlation.Four types of threshold

measurement were performed by means of random-dot stereograms: (1)static stereo

detection/discrimination; (2)stereomotion detection in dynamic random-dot stereograms

(temporally uncorrelated); (3)stereomotion detection in temporally correlated random-dot

stereograms; and (4)binocular detection of frontoparallel motion, Three normal subjects and

five subjects with unusually high stereoacuities were studied. In addition, two manipulations

were performed that altered stereomotion thresholds: changes in mean disparity, and image

defocus produced by positive spectacle lenses. Across subjects and conditions, stereomotion

thresholds were well correlated with stereo-discrimination thresholds. Stereo-motion was

poorly correlated with binocular frontoparallel-motion thresholds. These results suggest that

stereomotion is detected by means of registering changes in the output of the same disparity

detectors that are used to detect static disparities.

Cumming, B. G. (2002). “An unexpected specialization for horizontal disparity in primate primary

visual cortex.” Nature 418(6898): 633-636.

The horizontal separation of the eyes means that objects nearer or farther than the fixation

point project to different locations on the two retinae, differing principally in their horizontal

coordinates (horizontal binocular disparity). Disparity-selective neurons have generally been

studied with disparities applied in only one direction 1 (often horizontal), which cannot

determine whether the encoding is specialized for processing disparities along the horizontal

axis. It is therefore unclear if disparity selectivity represents a specialization for naturally

occurring disparities. I used random dot stereograms to study disparity-selective neurons from

the primary visual cortex (V1) of awake fixating monkeys. Many combinations of vertical and

horizontal disparity were used, characterizing the surface of responses as a function of two-

dimensional disparity. Here I report that the response surface usually showed elongation along

the horizontal disparity axis, despite the isotropic stimulus. Thus these neurons modulated

their firing rate over a wider range of horizontal disparity than vertical disparity. This

demonstrates that disparity-selective cells are specialized for processing horizontal disparity,

and that existing models(2,3) of disparity selectivity require substantial revision.



Cumming, B. G. and G. C. DeAngelis (2001). “The physiology of stereopsis.” Annual Review of

Neuroscience 24: 203-238.

Binocular disparity provides the visual system with information concerning the three-

dimensional layout of the environment. Recent physiological studies in the primary visual

cortex provide a successful account of the mechanisms by which single neurons are able to

signal disparity. This work also reveals that additional processing is required to make explicit

the types of signal required for depth perception (such as the ability to match features correctly

between the two monocular images). Some of these signals, such as those encoding relative

disparity, are found in extrastriate cortex. Several other lines of evidence also suggest that the

link between perception and neuronal activity is stronger in extrastriate cortex (especially MT)

than in the primary visual cortex.



Cumming, B. G., E. B. Johnston, et al. (1991). “Vertical Disparities and Perception of 3-Dimensional

Shape.” Nature 349(6308): 411-413.

THE information about depth and three-dimensional shape available from the horizontal

component of the stereo disparity field requires interpretation in conjunction with information

about ego-centric viewing distance (D). A novel computational approach for estimating D was

proposed by Mayhew and Longuet-Higgins 1,2, who demonstrated that the horizontal gradient

of vertical disparities uniquely specifies the viewing distance. We have now used random dot

stereograms in a shape judgement task to show that changes in vertical disparities have no

effect on perceived three-dimensional shape. Changes in ocular convergence do alter

perceived shape, suggesting substantial changes in the subjects' scaling of horizontal

disparities. We conclude that vertical disparities are not used to scale disparities for viewing

distance, and that extraretinal signals must be considered when analysing human three-

dimensional shape perception.



Cumming, B. G. and A. J. Parker (1994). “Binocular Mechanisms for Detecting Motion-in-Depth.”

Vision Research 34(4): 483-495.

There are in principle at least two binocular sources of information that could be used to

determine the motion of an object towards or away from an observer: such motion produces

changes in binocular disparities over time and also generates different image velocities in the

two eyes. Existing psychophysical and physiological evidence is reviewed. It is concluded that

these data are inconclusive concerning whether one or both of these sources of information are

used in primate vision. Thresholds were measured for disparity modulations in dynamic

(temporally uncorrelated) random dot stereograms (RDS), and for RDS in which the same

random dot pattern was used throughout (temporally correlated). Although the first stimulus

contains no consistent inter-ocular velocity differences, thresholds were generally slightly

lower for this stimulus than for temporally correlated stimuli. Sensitivity to the temporal

derivative of disparity is therefore adequate to account for human stereomotion detection. A

stimulus was devised in which monocular motion was clearly visible to each eye (with

opposite velocities) but in which all disparity changes were beyond the temporal resolution of

stereopsis. This produced no sensation of motion-in-depth. Similarly, stimuli beyond the

spatial resolution of stereopsis did not support stereomotion detection. These data strongly

suggest that stereomotion is primarily detected by means of temporal changes in binocular

disparity. We argue that there is no experimental evidence that supports the existence of a

mechanism sensitive to inter-ocular velocity differences.



Cumming, B. G. and A. J. Parker (1997). “Responses of primary visual cortical neurons to binocular

disparity without depth perception.” Nature 389(6648): 280-283.

The identification of brain regions that are associated with the conscious perception of visual

stimuli is a major goal in neuroscience(1). Here we present a test of whether the signals on

neurons in cortical area V1 correspond directly to our conscious perception of binocular

stereoscopic depth. Depth perception requires that image features on one retina are first

matched with appropriate features on the other retina. The mechanisms that perform this

matching can be examined by using random-dot stereograms(2), in which the left and right

eyes view randomly positioned but binocularly correlated dots. We exploit the fact that

anticorrelated random-dot stereograms (in which dots in one eye are matched geometrically to

dots of the opposite contrast in the other eye) do not give rise to the perception of depth(3)

because the matching process does not find a consistent solution. Anticorrelated random-dot

stereograms contain binocular features that could excite neurons that have not solved the

correspondence problem. We demonstrate that disparity-selective neurons in V1 signal the

disparity of anticorrelated random-dot stereograms, indicating that they do not unambiguously

signal stereoscopic depth. Hence single V1 neurons cannot account for the conscious

perception of stereopsis, although combining the outputs of many V1 neurons could solve the

matching problem. The accompanying paper(4) suggests an additional function for disparity

signals from V1: they may be important for the rapid involuntary control of vergence eye

movements (eye movements that bring the images on the two foveae into register).



Cumming, B. G., S. E. Shapiro, et al. (1998). “Disparity detection in anticorrelated stereograms.”

Perception 27(11): 1367-1377.

Recent physiological observations in which stimuli with opposite contrast signs in the two

eyes have been used (anticorrelated stereograms) show that these stimuli evoke responses in

primary visual cortex which are the reverse of responses to correlated stimuli. Psychophysical

investigations reveal no such reversals: reversed-contrast bars with crossed disparities are seen

in front of those with uncrossed disparities. For anticorrelated random-dot stereograms human

subjects perceive no depth at all, except at low dot densities. However, these human studies

were carried out with stimuli that differed in several ways from those used in physiological

studies. We therefore reexamined psychophysical responses using stimuli similar to those used

for physiological recordings. Our results confirm the previous findings: there is no evidence of

a reversed depth sensation for bar stereograms (crossed disparities are never seen behind

uncrossed disparities), and subjects are unable to detect depth in anticorrelated random-dot

stereograms at the densities used for the physiological recordings. The discrepancy between

the psychophysical data and the responses of single neurons in primary visual cortex suggests

that further processing outside area V1 is necessary to provide the signals that produce the

sensation of stereoscopic depth.



Curran, W. and O. J. Braddick (2000). “Speed and direction of locally-paired dot patterns.” Vision

Research 40(16): 2115-2124.

Phenomenal transparency in random-dot kinematograms is abolished when two motion

directions are 'locally-balanced' by pairing limited-lifetime dots at each location [Qian,

Andersen and Adelson (1994). Journal of Neuroscience, 14, 7357-7366]. Qian et al. also

report that locally-paired stimuli appear as directionless flicker when the paired dots differ in

their directions by 90 degrees or more. They attribute this to local inhibition between motion

detectors more than 45 degrees apart. We investigated perceived motion in such displays, by

requiring subjects to make direction and speed judgements with locally-paired stimuli

containing two directions 60, 90 or 120 degrees apart. Subjects perceived coherent motion in

these displays and made reliable direction judgements, indicating that the two motions are

combined rather than interfering destructively. Our results show that the judged motion of

locally-paired stimuli is in the vector-average direction of the two components. This vector-

averaging rule also applies when the two sets of component dots differ in their velocity.

Similarly, speed judgements comply with a vector-averaging rule for a range of speeds as well

as for mixed-speed stimuli. These results suggest that the abolition of transparency does not

necessarily imply abolition of a global motion percept. The local interaction abolishing

transparency is not exclusively inhibitory, at least for directions up to 120 degrees apart, but

generates a Vector combination of the superimposed motions. (C) 2000 Elsevier Science Ltd.

All rights reserved.



Dakin, S. C. (1997). “The Detection of Structure in Glass Patterns: Psychophysics and Computational

Models.” Vision Research 37(16): 2227-2246.

Examined the judgement of the mean orientation of textures composed either of short lines or

dipoles (Glass patterns). The effects of element length, density, and orientation variation are

described. Psychophysical data are compared with predictions from 4 schemes for extracting

features from Glass patterns: token matching, isotropic filtering, oriented filtering, and

"adaptive" filtering. Simulations indicate that neither models using isotropic filtering nor

token matching achieve human levels of performance on certain tasks. Adaptive filtering,

operating at a scale selected using the criterion described, provides good agreement with the

psychophysical data reported and is a practical scheme for deriving features using oriented

filters.



Dakin, S. C. (1997). “Glass patterns: Some contrast effects re-evaluated.” Perception 26(3): 253-268.

The relative contrast of features is known to be important in determining if they can be

grouped. Two manipulations of feature contrast have previously been used to criticise models

of visual grouping based on spatial filtering: high-pass filtering and reversal of contrast

polarity. The effects of these manipulations are considered in the context of the perception of

Glass patterns. It is shown that high-pass filtering elements, whilst destroying structure in the

output of low-pass filters, do not significantly disrupt the output of locally band-pass filters.

The finding that subjects can perceive structure in Glass patterns composed of high-pass

features therefore offers no evidence against such spatial filtering mechanisms. Band-pass

filtering models are shown to explain the rotation of perceived structure in Glass patterns

composed of opposite contrast features. However, structure is correctly perceived in patterns

composed of two 'interleaved' opposite contrast patterns, which is problematic for oriented

filtering mechanisms. Two possible explanations are considered: nonlinear contrast

transduction prior to filtering, and integration of local orientation estimates from first-order

and second-order mechanisms.



Dakin, S. C. (1999). “Orientation variance as a quantifier of structure in texture.” Spatial Vision 12(1):

1-30.

Considers how structure is derived from texture containing changes in orientation over space,

and proposes that multi-local orientation variance (the average orientation variance across a

series of discrete images locales) is an estimate of the degree of organization that is useful

both for spatial scale selection and for discriminating structure from noise. The oriented

textures used are Glass patterns, which contain structure at a narrow range of scales. The

effect of adding noise to Glass patterns, on a structure vs noise task, is compared to

discrimination based on orientation variance and template matching. At all but very low

densities, the variance model accounts well for human data. Next, both models' estimates of

tolerable orientation variance are shown to be broadly consistent with human discrimination of

texture from noise. However, neither model can account for Ss' lower tolerance to noise for

translational patterns than other patterns. Finally, to investigate how well these structural

measures preserve local orientation discontinuities, the author shows that the presence of a

patch of unstructured dots embedded in a Glass pattern produces a change in multi-local

orientation variance.



Dakin, S. C. and P. J. Bex (2001). “Local and global visual grouping: Tuning for spatial requency and

contrast.” Journal of Vision 1: 99-111.



Dakin, S. C. and P. J. Bex (2002). “Summation of concentric orientation structure: seeing the Glass or

the window?” Vision Research 42(16): 2013-2020.

Rotational Glass patterns are discrimnable from noise at substantially lower signal-to-noise

levels than translational patterns, a finding that has been attributed to the operation of

concentrically tuned units in cortical area V4 (Wilson, Wilkinson, & Asaad, Vis. Res. 37 (17)

(1997) 2325; Wilson & Wilkinson, Vis. Res. 38 (19) (1998) 2933). Under experimental

conditions similar to Wilson et al. We found this advantage to be largely contingent on the

pattern being viewed through a circular aperture. Because rotation of a random dot set cannot

lead to the presence of unmatched dots at the boundary of a circular aperture, the integrity of

low spatial frequency information at the boundary reliably indicates the presence of rotational,

but not translational, structure. When we removed this cue, either using a square aperture or

surrounding a round aperture with noise dots, none of the nine subjects tested showed any

statistically significant advantage for rotational Glass patterns (although at least two did take

longer to master the task with translational compared to rotational patterns). We go on to show

generally similar patterns of global integration for both rotational and translational patterns.

We conclude that this paradigm presently offers no concrete psychophysical evidence for

specialised concentric orientation detectors. (C) 2002 Elsevier Science Ltd. All rights

reserved.



Dakin, S. C. and P. J. Bex (2003). “Motion detection and the coincidence of structure at high and low

spatial frequencies.” Vision Research 43: 371-383.

We used filtered random dot kinematograms and natural images to examine how motion

detection depends the relative locations of structures defined at low and high spatial

frequencies. The upper displacement limit of motion, the lower displacement limit, and motion

coherence thresholds were unaffected by the degree of spatial coincidence between high and

low spatial frequency structures, i.e., whether they were consistent or inconsistent with a

single feature. However motion detection was possible between band-pass filtered random dot

patterns whose peak frequencies were separated by up to 4 octaves. The first result implicates

spatial frequency selective motion detectors that operate independently. The second result

implicates a motion system that can integrate the displacements of edges defined by widely

separated spatial frequencies. Both are required to account for the two results, and they appear

to operate under very similar conditions.



Dakin, S. C. and P. J. Bex (2003). “Response to Wilson & Wilkinson: Evidence for global processing

but no evidence for specialised detectors in the visual processing of Glass patterns.” Vision

Research 43(5): 565-566.



Dakin, S. C. and A. M. Herbert (1998). “The spatial region of integration for visual symmetry detection

(vol 265, pg 659, 1998).” Proceedings of the Royal Society of London Series B-Biological

Sciences 265(1413): 2455-2455.



Dakin, S. C. and R. F. Hess (1997). “The spatial mechanisms mediating symmetry perception.” Vision

Research 37(20): 2915-2930.

This paper examines the role of spatial frequency and orientation tuned channels in the

perception of visual symmetry. Subjects discriminated between band-pass filtered, white noise

textures that either did or did not contain vertical bilateral symmetry (VBS, i.e., around a

vertical midline) as a function of the spatial phase disruption imposed on the images,

Resistance to phase noise is largely scale- invariant for isotropically filtered images, but

horizontally filtered images are consistently more noise-resistant than vertical, However, when

stimuli are rotated through 90 deg (horizontal bilateral symmetry, HBS) performance is better

with vertically filtered images suggesting a general advantage for orientations orthogonal to

the axis of symmetry, At these orientations symmetry may be signaled directly by clusters of

features along the axis. Our data further suggest that the established disadvantage for HBS

may be attributable to an over-reliance on the output of horizontal filters. We compare models

which exploit feature clustering around the axis by measuring the co-alignment in the output

of oriented filters. Models using filters oriented orthogonal to the axis of symmetry predict the

psychophysical performance for isotropic patterns and for patterns filtered orthogonal to the

axis. For patterns filtered parallel to the axis, our data suggest that visual attention may play a

role. (C) 1997 Elsevier Science Ltd.



Dakin, S. C. and I. Mareschal (2000). “The role of relative motion computation in 'direction

repulsion'.” Vision Research 40(7): 833-841.

When two sets of intermixed dots move in different directions thr:perceived direction of each

is considerably shifted [Marshak & Sekuler (1979). Science, 205, 1399-1401; Mather &

Moulden, (1980). Quarterly Journal of Experimental Psychology, 32, 325-333)]. This

phenomenon has been attributed to 'repulsive' interactions between channels tuned to different

directions of motion. However, we report that it is not only the relative direction, but also the

density and speed of the sets, which determines the magnitude of the apparent shift. These

results are difficult to reconcile-with the notion of 'repulsive' interactions, and we describe an

alternative, functionally motivated explanation. In the natural environment, observed motion

results from objects moving over background surfaces that may themselves be mobile.

Disentanglement of motion signals therefore necessitates a computation of relative motion.

We propose that the phenomenon:of 'direction repulsion' results from a deliberate adjustment

of observed motion to compensate for an inferred source of 'background' motion. A simple

scheme to do this subtracts the weighted vector-sum of all motion signals from observed

motion. This relative motion computation quantitatively predicts the observed effects of the

density of do;sers on perceived direction: The effects of speed cannot be reconciled with the

scheme as it stands, but this could be due to the model's failure to consider the effect of

temporal frequency on the effective contrast of the sets. (C) 2000 Elsevier Science Ltd. All

rights reserved.



Dakin, S. C. and R. J. Watt (1996). Detection of bilateral symmetry using spatial filters. Human

Symmetry Perception and its Computational Analysis. C.W.Tyler. Utrecht, VSP: 187-207.



Das, A. and C. D. Gilbert (1995). “Receptive-Field Expansion in Adult Visual-Cortex Is Linked to

Dynamic Changes in Strength of Cortical Connections.” Journal of Neurophysiology 74(2):

779-792.

1. Receptive field (RF) sizes of neurons in adult primary visual cortex are dynamic, expanding

and contracting in response to alternate stimulation outside and within the RF over periods

ranging from seconds to minutes. The substrate for this dynamic expansion was shown to lie

in cortex, as opposed to subcortical parts of the visual pathway. The present study was

designed to examine changes in cortical connection strengths that could underlie this observed

plasticity by measuring the changes in cross-correlation histograms between pairs of primary

visual cortex neurons that are induced to dynamically change their RF sizes.2. Visually driven

neural activity was recorded from single units in the superficial layers of primary visual cortex

in adult cats, with two independent electrodes separated by 0.1-5 mm at their tips, and cross-

correlated on-line. The neurons were then conditioned by stimulation with an ''artificial

scotoma,'' a field of flashing random dots filling the region of visual space around a blank

rectangle enclosing the RFs of the recorded neurons. The neuronal RFs were tested for

expansion and their visually driven output again cross-correlated. After this, the neurons were

stimulated vigorously through their RF centers to induce the field to collapse, and the visually

driven output from the collapsed RFs was again cross-correlated. Cross-correlograms obtained

before and after conditioning, and after RF collapse, were normalized by their flanks to

control for changes in peak size due solely to fluctuations in spike rate.3. A total of 37 pairs of

neurons that showed distinct cross-correlogram peaks, and whose RF borders were clearly

discernible both before and after conditioning, were used in the final analysis. Of these neuron

pairs, conditioning led to a clear expansion of RF boundaries in 28 pairs, whereas in 9 pairs

the RFs did not expand. RFs that did expand showed no significant shifts in their orientation

preference, orientation selectivity, or ocularity.4. When the RFs of a pair of neurons expanded

with conditioning, the area of the associated flank-normalized cross-correlogram peaks also

increased (by a factor ranging from 0.84 up to 3.5). Correlograms returned to their

preconditioning values when RFs collapsed. Within the populaton of neurons that expanded

with conditioning, the subset of neurons starting with substantial RF overlap before

conditioning showed essentially no increase in cross-correlation peak area (peak areas

increased by factors ranging from 0.84 to 1.75 with a mean of 1.2 +/- 0.23), whereas the

complementary set of neuron pairs with low or no initial overlap showed a significant increase

in cross-correlation peak area (peak areas increased by factors ranging from 1.1 to 3.5 with a

mean of 1.72 +/- 0.53). RFs that did not expand showed no increases in their flank-normalized

cross-correlograms (correlogram peak area changed by a factor of 0.81 +/- 0.23 with

conditioning). Neuron pairs that showed no significant cross-correlation before conditioning

(i.e., neurons whose orientation preference differed by >40 degrees, or were highly directional

in opposite senses, or were separated by more than similar to 3 mm on the surface of the

cortex, or were highly monocular with opposite ocularity) showed no significant cross-

correlation after conditioning.5. Correlation strength did not change uniformly with

conditioning over the area of the RFs. We measured this inhomogeneity in the effects of

conditioning by obtaining correlograms with stimuli placed in different positions within the

RFs of each pair of neurons. In three neuron pairs where the RF expansion was highly

asymmetric, this comparison showed that correlation strength increased significantly only in

the RF subregions where the expansion was greater.



Davidson, R. M. and D. B. Bender (1991). “Selectivity for Relative Motion in the Monkey Superior

Colliculus.” Journal of Neurophysiology 65(5): 1115-1133.

1. Cells in the superficial layers of the colliculus were studied in immobilized monkeys

anesthetized with nitrous oxide. We examined sensitivity to the relative motion between two

stimuli: a small target in a cell's receptive field and a large random-dot back-ground pattern

that filled most of the visual field outside the receptive field.2. Most cells were nonselective

for either target direction or speed when the background pattern was stationary but were

selective for both direction and speed relative to a moving background. Selectivity for relative

motion was independent of the absolute direction and speed of both target and background.

When both moved at the same speed in the same direction, the response evoked by the target

was strongly suppressed. Changing the background direction relative to the target reduced the

suppression; suppression was minimal when the two moved in opposite directions. Selectivity

for relative direction was broad: the average tuning width at half-amplitude was 136-degrees.

When target and background moved in the same direction, increasing or decreasing

background speed relative to the target likewise reduced suppression. Average tuning width

for relative speed was 1.4 log units.3. Selectivity for relative motion was a global

phenomenon. Suppression was present even when the background pattern was excluded from

a region 10 times the receptive-field diameter. However, suppression gradually diminished

with increasing distance between the receptive field and the background pattern.4. Relative

motion selectivity was most common in the deeper part of the superficial layers. Ninety

percent of the cells below the middle of the stratum griseum superficiale were selective for

relative direction, whereas above this level only 45% of the cells were.5. Cells in the

magnocellular and parvocellular layers of the lateral geniculate nucleus did not show

selectivity for relative direction.6. We suggest that the lower one-half of the superficial grey

layer and the stratum opticum together constitute a subdivision of the superior colliculus that

is specialized to detect strong discontinuities in relative motion. Descending input by way of

the corticotectal tract is probably essential for the detection process. The projections from this

tectal motion zone to the pulvinar, and from there to prestriate cortex, may provide a feedback

pathway through which motion discontinuities such as occur at dynamic occulusion

boundaries can influence local feature detection by cortical neurons.



Dawson, M. and V. di Lollo (1990). “Effects of adapting luminance and stimulus contrast on the

temporal and spatial limits of short-range motion.” Vision Research 30(3): 415-429.

Examined perception of short-range motion in computer simulations and in psychological

experiments with 7 human Ss. The stimuli were random dots plotted on an oscilloscope in 2

sequential frames, separated by an interstimulus interval (ISI). The maximum spatial

displacement (d-sub(max)) was estimated between corresponding dots in the successive

frames, and the maximum ISI (t-sub(max)) was estimated at which coherent motion was

perceived 80% of the time. A strong effect of adapting luminance on the spatial and temporal

limits of motion perception was found: decrements in luminance produced marked increments

in d-sub(max ) and t-sub(max). However, d-sub(max ) and t-sub(max ) were not affected by

changes in stimulus contrast. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 567 of 887 in PsycINFO 1990-1992



De Bruyn, B. (1995). “Asymmetric spatial distributions of motion vectors yield characteristic errors in

direction judgements.” Vision Research 35(11): 1541-1545.

Examined whether the perceived direction of motion corresponds to the true direction of

translation or to the direction of the mean vector. Five observers with normal or corrected-to-

normal vision participated in 3 conditions with 5 random-dot patterns. Ss indicated of the

global direction of motion for each presentation of a stimulus. For the conditions tested, the

actual translation angle could not be recovered. The variation in the mean direction for a given

set of translation/expansion parameters was attributable to the spatial asymmetries of different

random-dot patterns. This effect was paralleled in perception since these spatial asymmetries

yielded a characteristic error in the perceived direction of object motion. Given the similarity

between the flow fields resulting from object motion and observer motion, the latter result

indicates that asymmetric distributions would affect heading judgments. (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 360 of 887 in PsycINFO 1993-1995

de Bruyn, B. and G. A. Orban (1988). “Human velocity and direction discrimination measured with

random dot patterns.” Vision Research 28(12): 1323-1335.

Studied 3 motion discrimination tasks in 5 experiments with 3 human observers using a

random dot pattern as stimulus: velocity discrimination, direction discrimination, and

discrimination of opposite directions. The analysis of the motion of random dot patterns was

based on motion sensitive mechanisms. Human velocity discrimination and direction

discrimination displayed a U-shaped dependence on the stimulus velocity. The velocity

discrimination curve obtained with the random dot pattern was similar to that previously

obtained with light bars. Discrimination of opposite directions was better than the 90%

response level at all speeds. However, at low contrast, opposite directions were reliably

discriminated only at intermediate speeds. Results show that the short range process of human

motion perception operates optimally at intermediate speeds (between 4 and 64 deg/sec-

super(-2)). (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 601 of 887

in PsycINFO 1988-1989



de Bruyn, B. and G. A. Orban (1989). “Discrimination of opposite directions measured with

stroboscopically illuminated random-dot patterns.” Journal of the Optical Society of America

A: Optics and Image Science 6(2): 323-328.

Two experiments with 2 emmetropic adults examined the effects of pattern size and spatial-

frequency content on the maximum spatial asynchrony by using a multiframe stroboscopic

display. Results indicate that the maximum displacement between sequentially presented

random-dot patterns (D-sub(max)) is not a fixed value. This is in agreement with data from

studies on stroboscopic motion in cats and monkeys and with results obtained with a 2-frame

display. D-sub(max ) depends on the size of the pattern as well as on spatial-frequency

content. Results obtained with the unfiltered, random-dot pattern also indicate that detectors

tuned to high spatial frequencies inhibit detectors tuned to low spatial frequencies. (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 602 of 887 in PsycINFO 1988-

1989



de Bruyn, B. and G. A. Orban (1990). “The importance of velocity gradients in the perception of three-

dimensional rigidity.” Perception 19(1): 21-27.

Two Ss viewed the display monocularly from a distance of 57 cm and indicated whether or

not an isotropic homogeneous stretch (a cloud of dots moving coherently, in a rigid manner)

had been perceived. Data show that sequential presentation of a number of random-dot

patterns, which when super-imposed yield an expanding flow field, leads to the perception of

a coherent motion toward the observer. The motion vectors in this type of flow field all radiate

from the origin. This percept of a global coherent expanding flow results only when the local

speeds are zero at the center and increase linearly toward the periphery. If all the dots radiate

outwards but have the same speed, a clear percept of 3-dimensional nonrigidity arises.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 565 of 887 in

PsycINFO 1990-1992



De Bruyn, B. and G. A. Orban (1999). “What is the speed of transparent and kinetic-boundary

displays?” Perception 28(6): 703-709.

To compare transparent motion and kinetic boundaries with unidirectional motion, in many

studies the relative motion is generated by superimposing or adjoining unidirectional motions

oriented in opposite directions. The presumption, tacitly underlying this comparison, is that

the two oppositely directed velocities are independent of one another as far as their speed is

concerned, ie the speed of the relative motion is presumed to be equivalent to the speed of the

unidirectional components. Here we report that the relative motion between dots moving in

opposite directions augments perceived speed. A constant-stimuli procedure was used to pair

transparent-motion or kinetic-boundary displays with unidirectional motion, and human

observers were asked to match the speed of the relative and unidirectional motions. The results

show that transparency and kinetic boundaries increase the perceived visual speed by about

50%, compared with the speed of the individual components.



de Vries, S. C., A. M. Kappers, et al. (1993). “Shape from stereo: A systematic approach using

quadratic surfaces.” Perception and Psychophysics 53(1): 71-80.

Used quadratic shapes in several psychophysical shape from stereo tasks in 4 experiments

involving the same 4 adult Ss. The shapes were represented in a 2-dimensional (2-D)

parameter space by the scale-independent shape index and the scale-dependent curvedness.

Using random-dot stereograms to depict the surfaces, it was found that the shape of hyperbolic

surfaces is slightly more difficult to recognize than the shape of elliptic surfaces. Results

showed that curvedness (and indirectly, scale) has little or no influence on shape recognition.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 483 of 887 in

PsycINFO 1993-1995



de Weert, C. M. (1979). “Colour contours and stereopsis.” Vision Research 19(5): 555-564.

Used 2 observers to investigate the role of color contours in stereopsis for random dot

stereograms and for figural stereo stimuli. The main conclusion is that for random dot

stereograms there were ratios of luminances for dots and background where stereopsis

disappeared, which points to the possibility that color differences alone are not sufficient to

evoke stereopsis. The ratio of the luminances, however, was not unity when dots and

background were of different colors. This points to color-specific effects. For figural

stereograms, stereopsis did not disappear at the aforementioned ratios of the luminances of

figure and background. Here, color certainly had a contribution to stereopsis on its own. In

another series of experiments the influence of color rivalry on the stereo thresholds was

investigated. Results suggest that the color information used in the figural system to evoke

stereopsis is the same for both eyes. (14 ref) (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 796 of 887 in PsycINFO 1978-1984



de Weert, C. M. and N. J. Wade (1988). “Compound binocular rivalry.” Vision Research 28(9): 1031-

1040.

Examined binocular rivalry with random dot patterns consisting of 3 colors: red, green, and

gray. Microstructure of the patterns was defined by the individual dots, and correspondence

between the microstructures in the 2 eyes was manipulated in 2 adults. Macrostructures were

defined by the distributions of red, green, and gray dots over the displays, so that they

consisted of orthogonally striped patterns. Degree of correspondence between the

microstructures was varied in Exp I, together with spatial frequency of the microstructure.

Rivalry periods of the macrostructures were briefer when the microstructures were in

correspondence. In Exp II the spatial frequencies of the macrostructures were varied. The

lower spatial frequency predominated for longer than the higher. Results are discussed in

terms of independent pathways for corresponding and rivalry stimulation. (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 606 of 887 in PsycINFO 1988-

1989



DeAngelis, G. C. and T. Uka (2003). “Coding of horizontal disparity and velocity by MT neurons in

the alert macaque.” Journal of Neurophysiology 89(2): 1094-1111.

We performed the first large-scale (n = 501), quantitative study of horizontal disparity tuning

in the middle temporal (MT) visual area of alert, fixating macaque monkeys. Using random-

dot stereograms, we quantified the direction tuning, speed tuning, horizontal disparity tuning,

and size tuning of each neuron. The vast majority (93%) of MT neurons were significantly

tuned for horizontal disparity. Although disparity tuning was generally quite robust, the

average disparity sensitivity of MT neurons was significantly weaker than their direction or

speed sensitivity as quantified using both an index of response modulation and an index of

signal-to-noise ratio. Disparity tuning was not correlated with direction or size tuning but

tended to be broader and weaker for neurons that preferred faster speeds of motion. By

comparison with recent studies, we find that disparity selectivity in MT is substantially

stronger than that seen in either primary visual cortex (V1) or area V4. In addition, MT

neurons are more broadly tuned for disparity than V1 neurons at comparable eccentricities.

Disparity tuning curves are very well described by Gabor functions for >80% of MT neurons.

The distribution of Gabor phases shows clear bimodality, indicating that MT neurons tend to

have odd-symmetric disparity tuning (unlike neurons in V1). The preferred disparities were

more strongly correlated with the phase parameter of the Gabor function than with the

positional offset parameter. In fact, for neurons with preferred disparities close to zero, the

positional offset tended to oppose the phase shift in specifying the disparity preference. We

suggest that this result reflects a strategy used to finely distribute the disparity preferences of

MT neurons, given the predominance of odd-symmetry and broad tuning.

Debecker, I., H. J. Macpherson, et al. (1992). “Negative Predictive Value of a Population-Based

Preschool Vision Screening-Program.” Ophthalmology 99(6): 998-1003.

Background. The Enhanced Vision Screening Program is a population-based vision screening

program that has, at present, examined 59,782 children. Its main goal is to detect amblyopia,

strabismus, and high refractive errors. An average of 11,910 4 1/2- to 5 1/2-year-old children

are screened yearly. The current study determines the negative predictive value of the

screening program: For a subject having passed the vision screening test, what is the

probability of not having amblyopia, strabismus, or high refractive errors?Methods: Of the

11,734 subjects who passed the vision screening, 200 were randomly chosen to undergo a

strictly defined gold standard examination by an orthoptist and an ophthalmologist.Results: Of

the 200 randomly chosen subjects, 157 underwent the gold standard evaluation. The negative

predictive value of the Enhanced Vision Screening Program was 97.6% for any potentially

vision-threatening ocular condition. It was 98.7% if we considered only the visually

significant ocular problems that the test was designed to detect.Conclusion: Because the

negative predictive value of the Enhanced Vision Screening Program is not 100%, some

children with amblyopia, strabismus, or refractive errors are missed. Occasionally, a rare,

potentially vision-threatening condition may go undetected. Parents should be made aware of

this when they receive the results of the vision screening.



Debruyn, B. (1995). “Asymmetric Spatial Distributions of Motion Vectors Yield Characteristic Errors

in Direction Judgments.” Vision Research 35(11): 1541-1545.

For a continuous flow field depicting a combined translation and expansion, there exists a

natural distribution of local motion directions whose mean direction corresponds to the

direction of translation. A random sampling of this distribution may introduce spatial

asymmetries and thus alter the mean direction. This statistical phenomenon has a perceptual

parallel: the spatial distribution of the. dots becomes relevant with respect to the perceived

global direction. The perceived direction of motion corresponds to the mean direction, not to

the actual direction of translation.



Debruyn, B. and G. A. Orban (1988). “Human Velocity and Direction Discrimination Measured with

Random Dot Patterns.” Vision Research 28(12): 1323-1335.



Debruyn, B. and G. A. Orban (1989). “Discrimination of Opposite Directions Measured with

Stroboscopically Illuminated Random-Dot Patterns.” Journal of the Optical Society of

America a-Optics Image Science and Vision 6(2): 323-328.



Decoux, B. (1997). “Self-supervised learning in cooperative stereo vision correspondence.”

International Journal of Neural Systems 8(1): 101-111.

This paper presents a neural network model of stereoscopic vision, in which a process of

fusion seeks the correspondence between points of stereo inputs. Stereo fusion is obtained

after a self-supervised learning phase, so called because the learning rule is a supervised-

learning rule in which the supervisory information is autonomously extracted from the visual

inputs by the model. This supervisory information arises from a global property of the

potential matches between the points. The proposed neural network, which is of the

cooperative type, and the learning procedure, are tested with random-dot stereograms (RDS)

and feature points extracted from real-world images. Those feature points are extracted by a

technique based on the use of sigma-pi units. The matching performance and the

generalization ability of the model are quantified. The relationship between what have been

learned by the network and the constraints used in previous cooperative models of stereo

vision, is discussed.



Dejonge, A. B. and C. Rashbass (1982). “Apparent Numerosity Differences in Pairs of Static Random-

Dot Patterns.” Perception 11(1): A32-A32.



Dev, P. (1975). “Perception of depth surfaces in random-dot stereograms: A neural model.”

International Journal of Man Machine Studies 7(4): 511-528.

Presents a model which segments the visual field into spatially disjoint regions, each region

characterized by a specific feature such as a texture or color. The neural connectivity

hypothesized to be necessary is formulated in mathematical terms, and the corresponding

neural network simulated on the digital computer. The properties of the network that result

from the postulated patterns of excitatory and inhibitory connectivity are investigated. It is

shown that the required connectivity is that of excitatory connections only between neurons

detecting similar features, and inhibitory connections between all feature-detecting neurons.

The model explains the phenomenon of stereopsis as investigated through the use of random-

dot stereograms. The process of depth perception through stereopsis is viewed as a

segmentation process with each segment characterized by a specific retinal disparity. It is

shown that the model suffices to detect the different depth surfaces embedded in the random-

dot patterns. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 845 of

887 in PsycINFO 1967-1977



Devries, S. C., A. M. L. Kappers, et al. (1993). “Shape from Stereo - a Systematic-Approach Using

Quadratic Surfaces.” Perception & Psychophysics 53(1): 71-80.

We used quadratic shapes in several psychophysical shape-from-stereo tasks. The shapes were

elegantly represented in a 2-D parameter space by the scale-independent shape index and the

scale-dependent curvedness. Using random-dot stereograms to depict the surfaces, we found

that the shape of hyperbolic surfaces is slightly more difficult to recognize than the shape of

elliptic surfaces. We found that curvedness (and indirectly, scale) has little or no influence on

shape recognition.



Deweerd, P., E. Vandenbussche, et al. (1992). “Texture Segregation in the Cat - a Parametric Study.”

Vision Research 32(2): 305-322.

We have investigated how different texture parameters affect texture segregation in the cat,

and which strategies cats use to solve the segregation task. Five cats were presented with

stimuli consisting of two adjacent panels. One side contained a square area of a particular

texture embedded in a different background texture; the other side was filled with only the

background texture. The animal's task was to detect at which side the texture difference was

presented. Sensitivity for the texture difference was assessed by making one aspect of the

texture (in most instances the size of the texture elements) dependent upon performance by

means of a staircase procedure. Among the most prominent parametric effects are those of

density and element position randomization. In general, segregation was optimal at

intermediate densities and deteriorated at larger and smaller densities. Element position

randomization caused a slight but systematic decrease in segregation performance.

Furthermore, we found texture elements at the border between different textures to be of

primary importance for segregation. Which strategy the animals used for solving the

segregation task depended upon the presence of random figure/background reversals in

subsequent stimulus presentations during training. The animals learned to detect texture

differences if these reversals were present, and without reversals, they learned to identify the

particular texture in the target square. Interestingly, parameter dependencies of segregation did

not depend upon the detection strategy used. We have speculated that the two different

strategies used by the cats to solve the segregation tasks are related to different hierarchical

levels of texture segregation which can be traced back to different stages of texture processing

in human models of segregation performance.



di Lollo, V. and W. F. Bischof (1991). “Yes, there is a half-cycle displacement limit for directional

motion detection.” Vision Research 31(4): 763-765.

Argues that O. J. Braddick and R. Cleary (see record 1991-23312-001) question the

sufficiency of the model and data presented by W. F. Bischof and V. Di Lollo (see record

1991-23311-001) for establishing the half-cycle displacement limit as a general rule of motion

perception. Experimental evidence is provided to support the findings. (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 547 of 887 in PsycINFO 1990-1992



Di Maio, V. (1998). “Threshold effect in visual perception of geometrical figures.” Perceptual and

Motor Skills 87(1): 340-342.

Filtering of the input image has been shown to play a central role in several aspects of visual

perception. In our experiments in visual perception of the area of geometrical figures the

orientation in random dot patterns, and some visual illusions, we have shown that a threshold

effect inferred from the filtering of the input image produces a perceptual error. This error has

been explained by using the concept of Image Function. The present paper is a brief review of

our experimental results and of the models we have proposed.

Diamond, R. and S. Carey (1990). “On the acquisition of pattern encoding skills.” Cognitive

Development 5(4): 345-368.

Evaluated 2 potential sources of developmental changes in pattern encoding: advances at a

perceptual level enabling better representation of the spatial relations among elements, and

acquisition of metaperceptual knowledge supporting a deliberate search for distinguishing

features. 56 children (aged 6, 10, and 12 yrs) and 120 undergraduates encoded high level

distortions of random dot configurations. In the 1st experiment, Ss matched exemplars to their

prototypes. In 2 other experiments, Ss learned to categorize distortions under 2 different

training conditions. Following training, Ss classified new instances into the learned categories.

The same pattern of developmental change was found in the matching task and in the

classification task: major gains between ages 6 and 12 yrs and continued gains to adulthood.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 533 of 887 in

PsycINFO 1990-1992



DiCarlo, J. J. and K. O. Johnson (1999). “Velocity invariance of receptive field structure in

somatosensory cortical area 3b of the alert monkey.” Journal of Neuroscience 19(1): 401-419.

This is the second in a series of studies of the neural representation of tactile spatial form in

cortical area 3b of the alert monkey. We previously studied the spatial structure of 330 area 3b

neuronal receptive fields (RFs) on the fingerpad with random dot patterns scanned at one

velocity (40 mm/sec; DiCarlo et al., 1998). Here, we analyze the temporal structure of 84

neuronal RFs by studying their spatial structure at three scanning velocities (20, 40, and 80

mm/sec). As in the previous study, most RFs contained a single, central, excitatory region and

one or more surrounding or flanking inhibitory regions. The mean time delay between skin

stimulation and its excitatory effect was 15.5 msec, Except for differences in mean rate, each

neuron's response and the spatial structure of its RF were essentially unaffected by scanning

velocity. This is the expected outcome when excitatory and inhibitory effects are brief and

synchronous. However, that interpretation is consistent neither with the reported timing of

excitation and inhibition in somatosensory cortex nor with the third study in this series, which

investigates the effect of scanning direction and shows that one component of inhibition lags

behind excitation. We reconcile these observations by showing that overlapping (in-field)

inhibition delayed relative to excitation can produce RF spatial structure that is unaffected by

changes in scanning velocity. Regardless of the mechanisms? the velocity invariance of area

3b RF structure is consistent with the velocity invariance of tactile spatial perception (e.g.,

roughness estimation and form recognition).



DiCarlo, J. J. and K. O. Johnson (2000). “Spatial and temporal structure of receptive fields in primate

somatosensory area 3b: Effects of stimulus scanning direction and orientation.” Journal of

Neuroscience 20(1): 495-510.

This is the third in a series of studies of the neural representation of tactile spatial form in

somatosensory cortical area 3b of the alert monkey. We previously studied the spatial

structure of >350 fingerpad receptive fields (RFs) with random-dot patterns scanned in one

direction (DiCarlo et al., 1998) and at varying velocities (DiCarlo and Johnson, 1999). Those

studies showed that area 3b RFs have a wide range of spatial structures that are virtually

unaffected by changes in scanning velocity. In this study, 62 area 3b neurons were studied

with three to eight scanning directions (58 with four or more directions). The data from all

three studies are described accurately by an RF model with three components: (1) a single,

central excitatory region of short duration, (2) one or more inhibitory regions, also of short

duration, that are adjacent to and nearly synchronous with the excitation, and (3) a region of

inhibition that overlaps the excitation partially or totally and is temporally delayed with

respect to the first two components. The mean correlation between the observed RFs and the

RFs predicted by this three-component model was 0.81. The three-component RFs also

predicted orientation sensitivity and preferred orientation to a scanned bar accurately. The

orientation sensitivity was determined most strongly by the intensity of the coincident RF

inhibition in relation to the excitation. Both orientation sensitivity and this ratio were stronger

in the supragranular and infragranular layers than in layer IV.



DiCarlo, J. J. and K. O. Johnson (2002). “Receptive field structure in cortical area 3b of the alert

monkey.” Behavioural Brain Research 135(1-2): 167-178.

More than 350 neurons with fingerpad receptive fields (RFs) were studied in cortical area 3b

of three alert monkeys. Random dot patterns, which contain all stimulus patterns with equal

probability, were scanned across these RFs at three velocities and eight directions to reveal the

RFs' spatial and temporal structure. Area 3b RFs are characterized by three components: (1) a

single, central excitatory region of short duration, (2) one or more inhibitory regions, also of

short duration, that are adjacent to and nearly synchronous with the excitation, and (3) a region

of inhibition that overlaps the excitation partially or totally and is temporally delayed with

respect to the first two components. As a result of these properties, RF spatial structure

depends on scanning direction but is virtually unaffected by changes in scanning velocity.

This RF characterization, which is derived solely from responses to scanned random-dot

patterns, predicts a neuron's responses to random patterns accurately, as expected, but it also

predicts orientation sensitivity and preferred orientation measured with a scanned bar. Both

orientation sensitivity and the ratio of coincident inhibition (number 2 above) to excitation are

stronger in the supra- and infragranular layers than in layer IV. (C) 2002 Elsevier Science

B.V. All rights reserved.



DiCarlo, J. J., K. O. Johnson, et al. (1998). “Structure of receptive fields in area 3b of primary

somatosensory cortex in the alert monkey.” Journal of Neuroscience 18(7): 2626-2645.

We investigated the two-dimensional structure of area 3b neuronal receptive fields (RFs) in

three alert monkeys. Three hundred thirty neurons with RFs on the distal fingerpads were

studied with scanned, random dot stimuli. Each neuron was stimulated continuously for 14

min, yielding 20,000 response data points. Excitatory and inhibitory components of each RF

were determined with a modified linear regression algorithm. Analyses assessing goodness-of-

fit, repeatability, and generality of the RFs were developed. Two hundred forty-seven neurons

yielded highly repeatable RF estimates, and most RFs accounted for a large fraction of the

explainable response of each neuron. Although the area 3b RF structures appeared to be

continuously distributed, certain structural generalities were apparent. Most RFs (94%)

contained a single, central region of excitation and one or more regions of inhibition located

on one, two, three, or all four sides of the excitatory center The shape, area, and strength of

excitatory and inhibitory RF regions ranged widely. Half the RFs contained almost evenly

balanced excitation and inhibition. The findings indicate that area 3b neurons act as local

spatiotemporal filters that are maximally excited by the presence of particular stimulus

features. We believe that form and texture perception are based on high-level representations

and that area 3b is an intermediate stage in the processes leading to these representations. Two

possibilities are considered: (1) that these high-level representations are basically somatotopic

and that area 3b neurons amplify some features and suppress others, or (2) that these

representations are highly transformed and that area 3b effects a step in the transformation.



Diehl, R. R. (1991). “Measurement of Interocular Delays with Dynamic Random-Dot Stereograms.”

European Archives of Psychiatry and Clinical Neuroscience 241(2): 115-118.

A psychophysical method of measuring interocular delay based on dynamic random-dot

stereograms is presented. The measurement requires only about 2 min. The sensitivity of this

method to detect differences in the transmission times of the two optic nerves is demonstrated

in patients with multiple sclerosis and in healthy subjects in whom interocular delays were

produced by using different luminance levels for each eye. This new method may be a useful

and economic method for monitoring the time course of optic neuritis.



Dijkstra, T. M. H., B. J. M. Melis, et al. (1990). “The Effects of Open-Loop Control of Moving 3-D

Random-Dot Patterns on Postural Responses.” Perception 19(3): 383-383.



Dill, M. and M. Fahle (1999). “Display symmetry affects positional specificity in same-different

judgment of pairs of novel visual patterns.” Vision Research 39(22): 3752-3760.

Deciding whether a novel visual pattern is the same as or different from a previously seen

reference is easier if both stimuli are presented to the same rather than to different locations in

the field of view (Foster & Kahn (1985). Biological Cybernetics, 51, 305-312; Dill & Fable

(1998). Perception and Psychophysics, 60, 65-81). We investigated whether pattern symmetry

interacts with the effect of translation. Patterns were small dot-clouds which could be mirror-

symmetric or asymmetric. Translations were displacements of the visual pattern symmetrically

across the fovea, either left-right or above-below. We found that same-different

discriminations were worse (less accurate and slower) for translated patterns, to an extent

which in general was not influenced by pattern symmetry, or pattern orientation, or direction

of displacement. However, if the displaced pattern was a mirror image of the original one

(along the trajectory of the displacement), then performance was largely invariant to

translation. Both positional specificity and its reduction in symmetric displays may be

explained by location-specific pre-processing of the visual input. (C) 1999 Elsevier Science

Ltd. All rights reserved.



Distler, C. and K. P. Hoffmann (1991). “Depth-Perception and Cortical Physiology in Normal and

Innate Microstrabismic Cats.” Visual Neuroscience 6(1): 25-41.

Evidence is presented that innate microstrabismus and abnormal cortical visual receptive-field

properties can occur also in cats without any apparent involvement of the Siamese or albino

genetic abnormalities in their visual system. A possible cause for microstrabismus in these

cats may be sought in an abnormally large horizontal distance between blind spot and area

centralis indicated by a temporal displacement of the most central receptive fields on both

retinae.Depth perception was found to be impaired in cats with innate microstrabismus.

Behavioral measurements using a Y-maze revealed in four such cats that the performance in

recognizing the nearer of two random-dot patterns did not improve when they were allowed to

use both eyes instead of only one. The ability of microstrabismic cats to perceive depth under

binocular viewing conditions only corresponded to the monocular performance of five normal

cats.Electrophysiological recordings were performed in the visual cortex (areas 17 and 18) of

four awake cats, two normal, and two innate microstrabismic animals. Ocular dominance and

orientation tuning of single neurons in area 17 and 18 were analyzed quantitatively.The

percentage of neurons in area 17 and 18 which could be activated through either eye was

significantly reduced to 49.7% in the microstrabismic animals when compared to the normal

cats (74.8%). "True binocular cells," which can only be activated by simultaneous stimulation

of both eyes, were significantly less frequent (1.6%) in microstrabismic cats than in normal

animals (10.4%). However, subthreshold binocular interactions were identical in both groups

of animals. In the strabismic animals, long-term binocular stimulation of monocular neurons

did not give a clear indication of alternating use of one or the other eye.The range of stimulus

orientations leading to discharge rates above 50% of the maximal response, i.e. the half-width

of the orientation tuning curves, was the same in the two groups of cats. However, orientation

sensitivity, i.e. the alternation in discharge rate per degree change in stimulus orientation, was

higher in cortical cells of normal cats than in those of microstrabismic cats.In normal and

microstrabismic cats, no clear sign of an "oblique effect," i.e. the preference of cortical

neurons for vertical and horizontal orientations compared to oblique orientations, could be

found neither in the incidence of cells with horizontal or vertical preferred orientation nor in

the sharpness of orientation tuning and sensitivity of these neurons.In summary, the receptive-

field properties reported here for awake innate microstrabismic cats are similar to those

reported in the literature for anesthetized cats with varying degrees of albinism and for cats

with artificial symmetrical strabismus surgically induced by sectioning the equivalent

extraocular muscles in both eyes. Our innate microstrabismic cats may provide, however, an

animal model for investigating the etiology of one form of naturally occurring strabismus.



Distler, C., F. Vital Durand, et al. (1999). “Development of the optokinetic system in macaque

monkeys.” Vision Research 39(23): 3909-3919.

Measured optokinetic nystagmus (OKN) in response to horizontal movement of a whole field

random dot pattern in infant macaque monkeys from the 1st wk to about 5 mo after birth,

using electrooculography. During monocular and binocular viewing conditions stimulus

velocities were varied between 10 and 120 deg./sec. Monocular stimulation in the

temporonasal direction yielded slow phase gain of the optokinetic system that was relatively

constant for a given stimulus velocity over the whole period of observation. Gain during

nasotemporal stimulation was also clearly present but significantly lower at early stages and

increased during further development. This asymmetry of monocular horizontal OKN clearly

depended on the stimulus velocity. At lower stimulus velocities (10-20 deg./sec) OKN was

largely symmetrical at 2-5 wks of age. At higher stimulus velocities (40 deg./sec) symmetry

was reached at about 12 wks of age or even much later (80-120 deg./sec). (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 182 of 887 in PsycINFO 1999



Distler, C., F. Vital-Durand, et al. (1999). “Development of the optokinetic system in macaque

monkeys.” Vision Research 39(23): 3909-3919.

Optokinetic nystagmus in response to horizontal movement of a whole field random dot

pattern was measured in infant macaque monkeys from the first week to about 5 months after

birth using electrooculography. During monocular and binocular viewing conditions stimulus

velocities were varied between 10 and 120 degrees/s. Monocular stimulation in the

temporonasal direction yielded slow phase gain of the optokinetic system which was relatively

constant for a given stimulus velocity over the whole period of observation. Gain during

nasotemporal stimulation was also clearly present but significantly lower at early stages and

increased during further development. This asymmetry of monocular horizontal optokinetic

nystagmus (OKN) clearly depended on the stimulus velocity. At lower stimulus velocities (10-

20 degrees/s) OKN was largely symmetrical at 2-5 weeks of age. At higher stimulus velocities

(40 degrees/s) symmetry was reached at about 12 weeks of age or even much later (80-120

degrees/s). (C) 1999 Elsevier Science Ltd. All rights reserved.



Ditzinger, T., M. Stadler, et al. (2000). “Noise improves three-dimensional perception: Stochastic

resonance and other impacts of noise to the perception of autostereograms.” Physical Review

E 62(2): 2566-2575.

Autostereograms can be perceived in different well-defined spatial levels. Therefore they are

an excellent tool with which to examine spatiotemporal processes of multistable three-

dimensional perception. We study properties of spatial ambiguity such as phase transitions

between different spatial levels and hysteresis in perception with and without noise. We show

that the perception of physical noise-which is added to the autostereograms in the form of a

random dot pattern-is dependent on the perceived spatial level. We demonstrate that noise can

be helpful for the perception of depth in some cases. We show that the signal-to-noise ratio of

depth perception is enhanced at an intermediate level of noise strength that is the signature of

stochastic resonance in depth perception.



Dodd, J. V., K. Krug, et al. (2001). “Perceptually bistable three-dimensional figures evoke high choice

probabilities in cortical area.” Journal of Neuroscience 21(13): 4809-4821.

The role of the primate middle temporal area (MT) in depth perception was examined by

considering the trial-to-trial correlations between neuronal activity and reported depth

sensations. A set of moving random dots portrayed a cylinder rotating about its principal axis.

In this structure-from-motion stimulus, the direction of rotation is ambiguous and the resulting

percept undergoes spontaneous fluctuations. The stimulus can be rendered unambiguous by

the addition of binocular disparities. We trained monkeys to report the direction of rotation in

a set of these stimuli, one of which had zero disparity. Many disparity-selective neurons in

area MT are selective for the direction of rotation defined by disparity. Across repeated

presentations of the ambiguous (zero-disparity) stimulus, there was a correlation between

neuronal firing and the reported direction of rotation, as found by Bradley et al. (1998).

Quantification of this effect using choice probabilities (Britten et al., 1996) allowed us to

demonstrate that the correlation cannot be explained by eye movements, behavioral biases, or

attention to spatial location. MT neurons therefore appear to be involved in the perceptual

decision process. The mean choice probability (0.67) was substantially larger than that

reported for MT neurons in a direction discrimination task (Britten et al., 1996). This implies

that MT neurons make a different contribution to the two tasks. For the depth task, either the

pool of neurons used is smaller or the correlation between neurons in the pool is larger.



Dodd, J. V., K. Krug, et al. (2001). “Perceptually bistable three-dimensional figures evoke high choice

probabilities in cortical area MT.” Journal of Neuroscience 21(13): 4809-4821.

Examined the role of the primate middle temporal (MT) area in depth perception by

considering the trial-to-trial correlations between neuronal activity and reported depth

sensations. A set of moving random dots portrayed a cylinder rotating about its principal axis.

In this structure-from-motion stimulus, direction of rotation is ambiguous and the resulting

percept undergoes spontaneous fluctuations. The stimulus can be rendered unambiguous by

the addition of binocular disparities. Two male monkeys were trained to report the direction of

rotation in a set of these stimuli, 1 of which had zero disparity. Across repeated presentations

of the ambiguous stimulus, there was a correlation between neuronal firing and reported

direction of rotation. Quantification of this effect using choice probabilities allowed the

authors to demonstrate that the correlation cannot be explained by eye movements, behavioral

biases, or attention to spatial location. MT neurons appear to be involved in the perceptual

decision process. The mean choice probability (0.67) was substantially larger than that

reported for MT neurons in a direction discrimination task. Results suggest that for the depth

task, either the pool of neurons used is smaller or the correlation between neurons in the pool

is larger. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 100 of 887 in

PsycINFO 2001 Part A



Doi, M. (1987). “The effects of memory load on a counting task: A working memory analysis for

developmental trends.” Japanese Journal of Psychology 58(1): 28-34.

Studied developmental aspects of short-term memory limitations. Human subjects: 36 normal

male and female Japanese children (aged 7-8 yrs). 36 normal male and female Japanese

children (aged 9-10 yrs). In 2 experiments Ss were asked to count and memorize the number

of dots in a series of random dot patterns and to report the memorized numbers at the end of

the series. Counting time and counting span were analyzed as measures of operational

efficiency and memory capacity. Experimental variables were grade level, degree of memory

load, number of dots, and interstimulus interval. (English abstract) (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 619 of 887 in PsycINFO 1985-1987



Domini, F., E. Blaser, et al. (2000). “Color-specific depth mechanisms revealed by a color-contingent

depth aftereffect.” Vision Research 40(4): 359-364.

Models of stereoscopic depth perception for both natural and random-dot images have focused

mainly on the matching of achromatic features of binocular images. Recently, a growing body

of research has investigated whether chromatic features can also contribute to the construction

of stereoscopic depth. Here we present experiments yielding color-contingent depth

aftereffects comparable in magnitude to those measured after adaptation to achromatic stimuli

as evidence of neural mechanisms tuned to both color and depth. Further-more, we report that

the locus of the combined processing of color and depth is likely to lie beyond the site of

binocular matching. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.



Domini, F. and C. Caudek (1999). “Perceiving surface slant from deformation of optic flow.” Journal

of Experimental Psychology-Human Perception and Performance 25(2): 426-444.

Perceived surface orientation and angular velocity were investigated for orthographic

projections of 3-D rotating random-dot planes, It was found that (a) tilt was accurately

perceived and (b) slant and angular velocity were systematically misperceived. It was

hypothesized that these misperceptions are the product of a heuristic analysis based on the

deformation, one of the differential invariants of the first-order optic flow. According to this

heuristic, surface attitude and angular velocity an recovered by determining the magnitudes of

these parameters that most likely produce the deformation of the velocity field, under the

assumption that all slant and angular velocity magnitudes have the same a priori probability,

The results of the present investigation support this hypothesis. Residual orientation

anisotropies not accounted for by the proposed heuristic were also found.



Domini, F., C. Caudek, et al. (1998). “Distortions of depth-order relations and parallelism in structure

from motion.” Perception & Psychophysics 60(7): 1164-1174.

Four experiments related human perception of depth-order relations in structure-from-motion

dis plays to current Euclidean and affine theories of depth recovery from motion.

Discrimination between parallel and nonparallel lines and relative-depth judgments was

observed for orthographic projections of rigidly oscillating random-dot surfaces. We found

that (1) depth-order relations were perceived veridically for surfaces with the same slant

magnitudes, but were systematically biased for surfaces with different slant magnitudes. (2)

Parallel (virtual) Lines defined by probe dots on surfaces with different slant magnitudes were

judged to be nonparallel. (3) Relative-depth judgments were internally inconsistent for probe

dots on surfaces with different slant magnitudes. It is argued that both veridical performance

and systematic misperceptions may be accounted for by a heuristic analysis of the first-order

optic flow.



Doner, J., J. S. Lappin, et al. (1984). “Detection of three-dimensional structure in moving optical

patterns.” Journal of Experimental Psychology: Human Perception and Performance 10(1): 1-

11.

Three experiments examined parameters affecting human observers' ability to detect the

global 3-dimensional (3D) organization of a random-dot display corresponding to the polar

projection of a rotating sphere. Ss were the authors and 3 other experienced observers. Results

indicate that the detection of 3D structure is critically dependent on the detectability of

motion, is disrupted by increased redundant information specifying the 2D location of points

in the display, and undergoes a rapidly increasing resistance to the disruptive effects of noise

with increasing numbers of frames. These results are inconsistent with existing theories

concerning the perception of 3D in moving displays, in that they indicate a high degree of

visual sensitivity to stimulus organizations with unique topological representations. (25 ref)

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 708 of 887 in

PsycINFO 1978-1984



Donnelly, M., C. Bowd, et al. (1997). “Direction discrimination of cyclopean (stereoscopic) and

luminance motion.” Vision Research 37(15): 2041-2046.

This study compared direction discrimination of cyclopean (stereoscopic) and luminance

motion involving stimuli equated for effective strength, The stimuli were random-walk

cinematogram (RWC) displays whose signal and noise discs were created from binocular

disparity differences embedded in a dynamic random-dot stereogram or from luminance

differences, Experiment 1 measured global motion detection thresholds for cyclopean and

luminance stimuli by manipulating the proportion of signal to noise discs, Detection

thresholds fbr cyclopean motion were about 25% whereas detection thresholds for luminance

motion were 5%, thus five times more cyclopean motion events than luminance events were

necessary to elicit threshold responding. Experiment 2 measured thresholds for discriminating

the direction of cyclopean and luminance motion under conditions of equal stimulus strength

by presenting the motion displays at equal multiples of detection threshold. Direction

discrimination thresholds (ranging from about 5-30 deg, depending upon conditions) were

similar for cyclopean and luminance motion, thus the precision with which the pooling of

local motion events in one direction can be discriminated from the pooling of events in a

slightly different direction is the same for cyclopean and luminance stimuli, The finding that

cyclopean motion information is pooled is consistent with the idea that the direction of

cyclopean motion is coded in the responses of a population of directionally selective

mechanisms. (C) 1997 Elsevier Science Ltd.



Dosher, B. A., M. S. Landy, et al. (1989). “Kinetic depth effect and optic flow: I. 3D shape from

Fourier motion.” Vision Research 29(12): 1789-1813.

53 different 3-dimensional (3D) shapes were defined by sequences of 2-dimensional views

(frames) of dots on a rotating 3D surface and presented to a total of 3 Ss in 6 experiments. Ss'

accuracy of shape identifications dropped from over 90% to less than 10% when either the

polarity of the stimulus dots was alternated from light-on-gray to dark-on-gray on successive

frames or when neutral gray interframe intervals were interposed. 3D shape discrimination

survived contrast reduction in standard stimuli, whereas it failed completely with polarity-

alternation even at full contrast. 3D shape identification did not require continuity of stimulus

tokens. Perceptual 1st-order analysis of optic flow is the primary substrate for structure-from-

motion computations in random dot displays because it offers sufficient quality of perceptual

motion at a sufficient number of locations. (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 583 of 887 in PsycINFO 1988-1989



Dowd, J. M., R. K. Clifton, et al. (1980). “Children Perceive Large-Disparity Random-Dot Stereograms

More Readily Than Adults.” Journal of Experimental Child Psychology 29(1): 1-11.



Dry, M. J. (2002). A generative transformational approach to the perception of Glass pattern structure.

Psychology. Adelaide, University of Adelaide.



Dubois, M. F. and H. Collewijn (1979). “Optokinetic reactions in man elicited by localized retinal

motion stimuli.” Vision Research 19(10): 1105-1115.

The role of different parts of the human retina in eliciting optokinetic pursuit was investigated

with continuously moving random dot or grid patterns; 9 Ss were used. With a central

stimulus, pursuit velocity (gain) in the 8 principal directions showed individual, but no

systematic differences. In the periphery, a centrifugal stimulus movement was much more

effective than a centripetal movement. This directional preference may assist foveation.

Pursuit open-loop gain was only moderately diminished by a decrease of the stimulus

diameter, but much more severely by deleting small parts in the center. This indicated that the

fovea is more powerful than the periphery in eliciting optokinetic pursuit. The distribution of

fast and slow nystagmic phases with respect to the primary position was unaffected by the use

of open-loop conditions or central scotomata. For all peripheral stimuli, the responses were

strongly enhanced by the Ss' specific attention. (25 ref) (PsycINFO Database Record (c) 2002

APA, all rights reserved) Record 786 of 887 in PsycINFO 1978-1984



Dumbrava, D., J. Faubert, et al. (2001). “Global motion integration in the cat's lateral posterior-pulvinar

complex.” European Journal of Neuroscience 13(12): 2218-2226.

Our laboratory previously showed that thalamic neurons in an extrageniculate nucleus, the

lateral posterior-pulvinar complex (LP-pulvinar) could perform higher-order neuronal

operations that had until then only been attributed to higher-level cortical areas. To further

assess the role of the thalamus in the analysis of complex percepts, we have investigated

whether neurons in the LP-pulvinar complex can signal the direction of motion of random-dot

kinematograms wherein the individual elements of the pattern do not provide coherent motion

cues. Our results indicate that a subset of LP-pulvinar cells can integrate the displacement of

individual elements into a global motion percept and that their large receptive fields permit the

integration of motion for elements separated by large spatial intervals. We also found that

almost all of the global motion-sensitive neurons were not systematically pattern-motion-

selective when tested with plaid patterns. The results indicate that LP-pulvinar cells can

perform the higher-level spatio-temporal integration required to detect the global displacement

of objects in a complex visual scene, further supporting the notion that extrageniculate

thalamic cells are involved in higher-order motion processing. Furthermore, these results

provide some evidence that there may be specialized mechanisms for processing different

types of complex motion within the LP-pulvinar complex.



Dupont, P., G. A. Orban, et al. (1994). “Many areas in the human brain respond to visual motion.”

Journal of Neurophysiology 72(3): 1420-1424.

Compared viewing of a moving random dot pattern with stationary viewing of the same

pattern but optimized stimulus size and dot density. Human Ss viewed a 3|| diameter random

dot pattern made of white dots on a dark background. During viewing, regional cerebral blood

flow (rCBF) was measured by positron emission tomography (PET). In addition to bilateral

foci at the border between Brodmann areas 19 and 37, a V1/V2 focus and a focus in the

cuneus, activation was observed in other visual areas in the cerebellum and in 2 other,

presumed vestibular areas: at the posterior bank of lateral sulcus and at the border of BA 2/40.

Results show that the sensitivity of PET activation studies can be increased by optimizing the

visual stimulus. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 426 of

887 in PsycINFO 1993-1995



Dupont, P., G. A. Orban, et al. (1994). “Many Areas in the Human Brain Respond to Visual-Motion.”

Journal of Neurophysiology 72(3): 1420-1424.

1. The regions of the human brain responsive to motion were mapped using the (H2O)-O-15

position emission tomography (PET) activation technique and compared by viewing a moving

random dot pattern with a stationary dot pattern. The stimulus was optimized in dot density

and 3 degrees in diameter. 2. In addition to bilateral foci at the border between Brodmann

areas 19 and 37, a V1/V2 focus and a focus in the cuneus reported earlier, we observed

activations in other visual areas (lower BA 19 and the parieto-occipital fissure) in the

cerebellum and in two other, presumed vestibular areas, the posterior bank of lateral sulcus

and at the border of BA 2/40.3. Homologies between monkey and human cortex are discussed.



Durand, J. B., S. P. Zhu, et al. (2002). “Neurons in parafoveal areas V1 and V2 encode vertical and

horizontal disparities.” Journal of Neurophysiology 88(5): 2874-2879.

Stereoscopic vision mainly relies on binocular horizontal disparity (HD), and its cortical

encoding is well established in the foveal representation of the visual field. The role of vertical

disparity (VD) is more controversial. Thus far, in the monkey, very few studies have

investigated the HD sensitivity beyond 5degrees of retinal eccentricity and no evidence of a

real encoding of VD exists in the parafoveal representation of areas V1 and V2. Using

dynamic random dot stereograms, we have tested both HD and VD selectivities in the

parafoveal representation of V1 (calcarine V1) and V2 (eccentricities > 10degrees) in a

behaving monkey. HD and VD selectivities have been characterized using fitting with Gabor

function. A large proportion of the tested cells were both HD and VD selective (47%) and, to a

lesser extent, HD selective only (8%) or VD selective only (23%). We found a real encoding

of VD, with the same diversity in the tuning profiles as described for HD, that cannot be

assimilated to a simple perturbation of the HD matching process. Moreover, the VD encoding

had a finer scale than the HD one, which is coherent with the smaller range of naturally

occurring VD. For the HD encoding, both the percentage of selective cells and the tuning

parameters were close to those reported in foveal V1. These results show that, at parafoveal

eccentricities in V1 and V2, disparity detectors are tuned to both horizontal and vertical

dimensions of the positional disparity existing between matched features in both retinas.



Durgin, F. H. (2001). “Texture contrast aftereffects are monocular; texture density aftereffects are

binocular.” Vision Research 41(20): 2619-2630.

Two experiments examined interocular transfer for simple and dynamic aftereffects of density

and contrast. Simple aftereffects of texture contrast were shown to be primarily monocular.

Texture density aftereffects were shown to be primarily binocular. Similarly, dynamic

aftereffects to repeated changes in contrast were found to be completely monocular; those to

repeated changes in density were found to be entirely binocular. Since contrast and density

aftereffects differ in their sensitivity to eye-of-origin, they likely depend on different neural

loci, and are not manifestations of the same underlying adaptation. Consistent with this

conclusion, it is proposed that. whereas contrast normalization (and perhaps contrast

aftereffects) may be localized to simple cells in Vl, density coding and normalization require

computations only available in complex cells and beyond. (C) 2001 Elsevier Science Ltd. All

rights reserved.



Duwaer, A. L. (1982). “Patent Stereopsis with Diplopia in Random-Dot Stereograms.” Perception

11(1): A24-A24.



Duwaer, A. L. (1983). “Patent Stereopsis with Diplopia in Random-Dot Stereograms.” Perception &

Psychophysics 33(5): 443-454.



Dzhafarov, E. N., R. Sekuler, et al. (1993). “Detection of Changes in Speed and Direction of Motion -

Reaction-Time Analysis.” Perception & Psychophysics 54(6): 733-750.

Observers reacted to the change in the movement of a random-dot field whose initial velocity,

V-0, was constant for a random period and then switched abruptly to another value, V-1. The

two movements, both horizontally oriented, were either in the same direction (speed

increments or decrements), or in the opposite direction but equal in speed (direction reversals).

One of the two velocities, V-0 or V-1, could be zero (motion onset and offset, respectively). In

the range of speeds used, 0-16 deg/sec (dps), the mean reaction time (MRT) for a given value

of V-0 depended on \V-1 - V-0\ only: MRT approximate to r + c(V-0)/\V-1 - V-0\(beta),

where beta = 2/3, r is a velocity-independent component of MRT, and c(V-0) is a parameter

whose value is constant for low values of V-0 (0-4 dps), and increases beginning with some

value of V-0 between 4 and 8 dps. These and other data reviewed in the paper are accounted

for by a model in which the time-position function of a moving target is encoded by mass

activation of a network of Reichardt-type encoders. Motion-onset detection (V-0 = 0) is

achieved by weighted temporal summation of the outputs of this network, the weights

assigned to activated encoders being proportional to their squared spatial spans. By means of a

''subtractive normalization,'' the visual system effectively reduces the detection of velocity

changes (a change from V-0 to V-1) to the detection of motion onset (a change from 0 to V-1 -

V-0). Subtractive normalization operates by readjustment of weights: the weights of all

encoders are amplified or attenuated depending on their spatial spans, temporal spans, and the

initial velocity V-0. Assignment of weights and weighted temporal summation are thought of

as special-purpose computations performed on the dynamic array of activations in the motion-

encoding network, without affecting the activations themselves.



Dzhafarov, E. N., R. Sekuler, et al. (1993). “Detection of changes in speed and direction of motion:

Reaction time analysis.” Perception and Psychophysics 54(6): 733-750.

Proposes a possible mechanism by which the human visual system detects changes in the

fronto-parallel movement of a visual target. Observers reacted to the change in the movement

of a random-dot field whose initial velocity, V-sub-0, was constant for a random period and

then switched abruptly to another value, V-sub-1. The 2 movements, both horizontally

oriented, were either in the same direction (speed increments or decrements), or in the

opposite direction but equal in speed (direction reversals). One of the two velocities, V-sub-0

or V-sub-1, could be zero (motion onset and offset, respectively). Data reviewed in the paper

are accounted for by a model in which the time-position function of a moving target is

encoded by mass activation of a network of Reichardt-type encoders. By means of a

"subtractive normalization," the visual system effectively reduces the detection of velocity

changes to the detection of motion onset. (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 465 of 887 in PsycINFO 1993-1995



Eagle, R. A. (1996). “What determines the maximum displacement limit for spatially broadband

kinematograms?” Journal of the Optical Society of America a-Optics Image Science and

Vision 13(3): 408-418.

Two experiments are described that are designed to investigate what determines the maximum

spatial displacement detectable (d(max)) for spatially broadband patterns exposed in a two-

frame motion sequence. In experiment 1, d(max) was found to be 1.63 times greater for a two-

dimensional (2-D) broadband random pattern with a 1/f Fourier amplitude spectrum (equal

contrast in each octave) than for a 2-D binary-valued random-dot pattern with a flat spectrum

(higher contrast in higher-frequency octaves). In experiment 2, d(max) was shown to vary in

inverse proportion to the lowest stimulus frequency for random patterns with a one-octave

bandwidth and normalized contrast. Furthermore, when these five one-octave patterns were

summed together, d(max) for this new five-octave pattern was found to be only 1.46 times

lower than d(max) for the lowest-frequency one-octave pattern presented alone. A model is

described in which direction discrimination is based on the nearest-neighbor matching of zero

crossings in the output of a single-spatial-filter bandpass in both spatial frequency and

orientation. Data from the model show that the difference between d(max) for the five-octave

and the lowest one-octave patterns can be accounted for by the same filter passing some of the

additional higher frequencies in the former pattern. Furthermore, it is argued that all the data

can be accounted for by assuming that d(max) is determined by the coarsest spatial filter

activated by each stimulus. Modeling the results of both experiments suggests that the

bandwidth of this filter is similar to 2.6 octaves and reaches peak sensitivity at similar to 0.47

c/deg. The model is shown to be capable of accounting for a wide range of other two-frame

d(max) data. (C) 1996 Optical Society of America



Eagle, R. A. (1997). “Independent processing across spatial frequency in moving broadband patterns.”

Perception 26(8): 961-976.

The aim of the experiments was to discover whether the visual system has independent access

to motion information at different spatial scales when presented with a broadband stimulus.

Subjects were required to discriminate between a pair of two-frame motion sequences, one

containing a coherently displacing pattern and the other containing a pattern with high-

frequency noise. The stimuli were either narrowband (1 octave) or broadband (6 octaves

spanning 0.23-15.0 cycles deg(-1)) and their power spectra were either flat or followed a

1/f(2) function. For the broadband stimuli, noise was introduced cumulatively into

increasingly lower frequencies. For the narrowband stimuli, noise was introduced into the

same frequency band as the signal. All stimuli could be defined by the lowest noise frequency

(n(1)) they contained. For each stimulus, the largest spatial displacement across the two

frames at which the task could be performed was measured (d(max)). For the narrowband

stimuli, d(max) increased as n(1) was lowered, This was true over the entire frequency range

for the 1/f(2) stimuli, though the task became impossible for the flat-spectrum stimuli at the

lowest frequencies. This is attributed to the very low contrast of these latter stimuli. The

d(max) values for the broadband stimuli tended to shadow those of the narrowband stimuli

with the equivalent values of n(1) being around 25% lower. The data were modelled by

spatiotemporally filtering the stimuli and considering the amount of directional power in the

signal and noise sequences. The results suggest that there must be multiple spatial-frequency

channels in operation, and that for broadband patterns the visual system has perceptual access

to these individual channel outputs, utilising different filters depending on the task

requirements.



Eagle, R. A. and B. J. Rogers (1991). “Maximum Displacement (Dmax) as a Function of Density,

Patch Size, and Spatial-Filtering in Random-Dot Kinematograms.” Investigative

Ophthalmology & Visual Science 32(4): 893-893.

Eagle, R. A. and B. J. Rogers (1996). “Motion detection is limited by element density not spatial

frequency.” Vision Research 36(4): 545-558.

Two-frame random-element kinematograms were used to study the matching algorithm

employed by the visual system to keep track of moving elements. Previous data have shown

that the maximum spatial displacement detectable (d(max)) for random-dot kinematogram

stimuli increases both with increasing dot size and with decreasing centre frequency for

spatially band-pass kinematograms. Both of these findings could be explained by either (i) a

matching algorithm sensitive to the number of false targets in the display (informational limit)

or (ii) spatial-frequency tuned sensors hardwired for detecting displacements of a constant

proportion of their preferred frequency (phase-based limit), The present experiment was

designed to differentiate between these alternative explanations. The stimuli were band-pass

filtered (difference-of-Gaussian) random-dot patterns, The combination of six dot densities

and three filter sizes produced 18 experimental conditions and allowed independent control of

the spectral content and filtered-element density of the stimuli, When the dot density was high,

d(max) was larger for the coarse-filtered stimuli, as predicted by both theories, There was also

a critical dot density for each filter size, above which d(max) was constant but below which

d(max) rose sharply, This critical density was higher for fine-filtered stimuli such that at the

lowest dot density of 0.025%, d(max) was constant for all filter sizes. In support of the

informational limit model, d(max) was found to be directly proportional to the two-

dimensional spacing of filtered elements, In contrast, d(max) varied from 0.6 to 8.5 cycles of

the stimulus peak frequency, suggesting that a phase-based model of motion detection cannot

account for the results.



Eagle, R. A. and B. J. Rogers (1997). “Effects of dot density, patch size and contrast on the upper

spatial limit for direction discrimination in random-dot kinematograms.” Vision Research

37(15): 2091-2102.

Two-frame random-dot kinematograms (RDKs) of different dot density, area and contrast

were used to study the spatial properties of the human visual motion system, It was found that

the maximum spatial displacement at which observers could reliably discriminate the direction

of motion (d(max)) increased gradually by a factor of up to 6.4 as dot density was decreased

from 50 to 0.025% for high Michelson contrast (0.997) stimuli. As stimulus area was reduced

from 645 deg(2), this trend gradually disappeared so that by a stimulus area of 2.56 deg(2),

there was no effect of density upon d(max). A further experiment investigated the effects of

reducing Michelson contrast from 0.77 to 0.2 on d(max) over this same range of dot densities,

It was found that at the highest densities, d(max) declined as contrast was reduced,

Furthermore, for contrasts at and below 0.4, d(max) was invariant of density over the range

50-5%. These results can be accounted for by the fact that both reducing contrast, while

keeping density fixed, and reducing density, while maintaining a fixed high contrast, reduce

the stimulus mean luminance, For all contrasts, decreasing density below 5% led to an

increase in d(max). However, the rate of this increase was slower for the lower contrast

stimuli, A two-stage model based on bandpass filtering followed by an informationally limited

motion detection stage is proposed and shown to provide a good account of these data. (C)

1997 Elsevier Science Ltd.



Earle, D. C. (1985). “Perception of Glass pattern structure with stereopsis.” Perception 14: 545-552.

Presents stereograms which demonstrate that the perceptual salience of local and global

structure Glass patterns (the superimposition of 2 sets of pattern elements, where the 1st is a

random or pseudorandom array of elements and the 2nd is a geometrical transformation of the

1st set) may be destroyed or created by the introduction of stereoscopic depth effects in 2-

dimensional projections. Novel 3-dimensional pattern structures can also be produced.

Proposals concerning the nature of the binocular primal sketch are evaluated in light of these

findings, which are consistent with the view that depth derived from disparity information is

explicitly represented in the primal sketch.



Earle, D. C. (1986). “Surface contours, Glass Patterns, and a slant illusion.” Perception 15: 537-540.

In a pattern of segments of contours in which a set of surfaces is perceived that contains an

illusory slant, it is conjectured that the slant illusion is a manifestation of the processes by

which depth is derived from surface contour information. It is demonstrated that

corresponding figures constructed from sinusoidal moire patterns produce similar effects. It is

concluded that the structure of moire patterns provides a sufficient input representation for the

processes by which surface shape is recovered from surface contours.



Earle, D. C. (1991). “Some observations on the perception of Marroquin patterns.” Perception 20(6):

727-731.

Presents demonstrations to show that the perception of structure in Marroquin patterns is

disrupted if the dots comprising the pattern have opposite contrast polarity and if the dots

comprising the pattern are separated in stereoscopic depth. It is also demonstrated that the

perception of structure in a Marroquin pattern is made possible if the pattern is separated in

stereoscopic depth from noise dots, where the pattern structure cannot be perceived in either

half of the unfused stereogram. In these respects the perception of Marroquin patterns is

similar to the perception of Glass patterns. Findings are consistent with the proposal that the

perception both of Marroquin and of Glass patterns is based on the construction of virtual

lines.



Earle, D. C. (1999). “Glass patterns: grouping by contrast similarity.” Perception 28(11): 1373-1382.

Recent work has shown that certain contrast phenomena associated with Glass patterns can be

accounted for by filtering mechanisms applied within the luminance or energy domain.

Hitherto, these phenomena were regarded as problematic for energy-processing models, and

were taken as evidence in support of symbolic-processing accounts. An additional, and

controversial, contrast effect is investigated. It is shown that in a Glass pattern consisting of

simultaneous vertical and horizontal translations of different contrast strength, the most salient

structure is determined by grouping (pairing) of the two low-contrast elements of the pattern.

The finding that grouping in such patterns is by contrast similarity, as opposed to energy, is

consistent with the symbolic-processing approach, but has yet to be accounted for by filtering

mechanisms.



Eastman, K. E. and H. S. Hock (1999). “Bistability in the perception of motion and stationarity: Effects

of temporal asymmetry.” Perception and Psychophysics 61(6): 1055-1065.

Investigated whether the failure to perceive motion for a seemingly adequate stimulus is the

result of inhibitory interactions within the ensemble of stimulus-activated motion detectors or

the result of inhibition of motion detectors by concurrently activated position detectors. The

study required that 4 college students perceive a displaced 3-dot figure in a background of

random dot motion. In the temporal symmetry condition, the figure was presented for the

same duration in its 2 locations; either figure or random motion was perceived, depending on

the number of noise dots. In the temporal asymmetry condition, the figure was presented for

different durations in its 2 locations; figure motion, a single, stationary figure in a fixed

position, or random noise was perceived, again depending on the number of noise dots.

Competition between these percepts was established by an analysis of switching rates and by

an experiment demonstrating the presence of hysteresis as noise levels were gradually

increased and decreased across the figure-motion and figure-stationarity boundaries. This

evidence suggests the presence of strong inhibitory competition between motion- and position-

detecting mechanisms. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record

181 of 887 in PsycINFO 1999



Eby, D. W. (1995). “Perceptual Collapse of 3-Dimensional Structure-from-Motion Parallax.”

Perceptual and Motor Skills 80(1): 147-154.

This study concerned how perceived depth collapses after asymptotic depth is reached and the

information specifying depth is abruptly removed. The stimuli were random-dot, computer-

generated three-dimensional objects and the depth information was motion parallax. Motion

parallax was removed in two ways. In the first method, the depth of all object points was

reassigned to zero, simulating a disk. In the second method, a rotation of the object was

introduced in such a way that a degenerate case of motion parallax was produced. The results

showed that judgments of depth slowly collapsed once motion parallax was removed. Over-

all, judgments of depth required about the same duration to collapse as was required for the

judgments to build up to asymptotic levels (about 750 msec.). Finally, depth collapsed more

slowly when the motion parallax was removed by redefining the object as a disk than when

removed using the other method.

Eby, D. W. (1995). “Perceptual collapse of three-dimensional structure from motion parallax.”

Perceptual and Motor Skills 80(1): 147-154.

Examined how perceived depth collapses after asymptotic depth is reached and the

information specifying depth is abruptly removed. The stimuli were random-dot, 3-

dimensional objects. Ss were 4 paid graduate students. Motion parallax was removed in 2

ways: In the 1st method, the depth of all object points was reassigned to zero, simulating a

disk. In the 2nd method, a rotation of the object was introduced in such a way that a

degenerate case of motion parallax was produced. Judgments of depth slowly collapsed once

motion parallax was removed. Overall, judgments of depth required about the same duration

to collapse as was required for the judgments to build up to asymptotic levels. Finally, depth

collapsed more slowly when the motion parallax was removed by redefining the object as a

disk. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 407 of 887 in

PsycINFO 1993-1995



Edwards, M. and D. R. Badcock (1995). “Global Motion Perception - No Interaction between the First-

Order and 2nd-Order Motion Pathways.” Vision Research 35(18): 2589-2602.

The experiments reported here address the issue of whether the pathways which extract

motion from first-order and second-order spatial patterns remain separate or whether they

combine at some higher level in the motion system to form a single pathway. The question is

addressed by investigating the interaction of first-order and second-order stimuli in the

processing of a global-motion stimulus [a variant of the task introduced by Newsome & Pare

(Journal of Neuroscience, 8, 2201-2211, (1988)]. Two experimental procedures were used.

The first consisted of determining the effect of the addition of dots of one type (e.g. first-

order) undergoing purely random motion on the ability to extract the global-motion signal

carried by dots of the other type (e.g. second-order). The second experimental procedure

consisted of determining the effect of maintaining a coherent-motion signal in one type of dot,

moving in the opposite direction to the global-motion direction, on the ability to extract the

global-motion signal carried by dots of the other type. The dots were matched for their

effectiveness in producing a global motion percept and the results for both procedures were

the same. First-order dots impaired the ability to extract second-order global-motion, and

second-order dots had no effect on first-order global-motion extraction. It is argued that the

sensitivity of the second-order global-motion system to the first-order dots is due to the ability

of the second-order local-motion detectors to detect these dots. The present results are thus

interpreted as indicating that the first-order and second-order motion pathways remain

separate up to and including the level in the motion system at which global-motion signals are

extracted.



Edwards, M. and D. R. Badcock (1995). “Global motion perception: No interaction between the first-

and second-order motion pathways.” Vision Research 35(18): 2589-2602.

Three experiments investigated the interaction of 1st- and 2nd-order motion pathways in the

processing of a global-motion (GM) stimulus in 5 observers. Two experimental procedures

were used to determine (1) the effect of the addition of dots of 1 type (e.g., 1st-order)

undergoing purely random motion on the ability to extract a GM signal carried by dots of the

other type (e.g., 2nd-order); and (2) the effect of maintaining a coherent-motion signal in 1

type of dot, moving in the opposite direction to the GM direction, on the ability to extract a

GM signal carried by dots of the other type. The dots were matched for their effectiveness in

producing a GM percept. First-order dots impaired 2nd-order GM extraction, and 2nd-order

dots had no effect on 1st-order GM extraction. Results indicate that 1st-order and 2nd-order

motion pathways remain separate up to and including the level in the motion system at which

GM signals are extracted. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 381 of 887 in PsycINFO 1993-1995



Edwards, M., D. R. Pope, et al. (2000). “First- and second-order processing in transient stereopsis.”

Vision Research 40(19): 2645-2651.

Large-field stimuli were used to investigate the interaction of first- and second-order pathways

in transient-stereo processing. Stimuli consisted of sinewave modulations in either the mean

luminance (first-order stimulus) or the contrast (second-order stimulus) of a dynamic-random-

dot field. The main results of the present study are that: (1) Depth could be extracted with both

the first-order and second-order stimuli; (2) Depth could be extracted from dichoptically

mixed first- and second-order stimuli, however, the same stimuli, when presented as a motion

sequence, did not result in a motion percept. Based upon these findings we conclude that the

transient-stereo system processes both first- and second-order signals, and that these two

signals are pooled prior to the extraction of transient depth. This finding of interaction

between first- and second-order stereoscopic processing is different from the independence

that has been found with the motion system. (C) 2000 Elsevier Science Ltd. All rights

reserved.



Eggert, T. and Z. Kapoula (1995). “Position Dependency of Rapidly Induced Saccade Disconjugacy.”

Vision Research 35(23-24): 3493-3503.

We tested the ability of normal subjects to alter the conjugacy of their saccades in a position-

specific manner, Five subjects dichoptically viewed a stereogram produced by two random-

dot patterns, They immediately perceived a three-dimensional wedge with its apex closer to

them, They were asked to saccade for 15 min back and forth between the apex and two lateral

dots of the wedge, For fixation sequences between centre-right-centre, saccades immediately

became larger in the right eye,For sequences between centre-left-centre, saccades immediately

became larger in the left eye, For two subjects this non-monotonic position-specific

disconjugacy compensated for the disparity of the stereogram almost perfectly, The

disconjugacy persisted even under monocular viewing of one of the random-dot patterns. It

diminished or disappeared immediately, however, when the random-dot pattern was shifted on

the screen, We suggest the existence of a fast learning mechanism capable of producing

;position-specific disconjugacy by associating saccades with disparity, Such a mechanism

would use a visual reference rather than the position of the eyes in the orbit.



Ehrlich, S. M. (1999). Analysis of the visual information for self-motion perception: Effect of depth

cues and landmarks.

When presented with random-dot displays depicting observer movement across a ground

plane or through a cloud, observers cannot determine their direction of self-motion accurately

in the presence of rotational flow without appropriate extra-retinal information (Royden,

Crowell, & Banks, 1994). It is not surprising that observers incorrectly perceive curved paths

with simulated eye rotations rather than the depicted linear path. This condition involves a cue

conflict between the retinal and extra-retinal information. In particular, the retinal information

is ambiguous (and can correspond to a linear path plus gaze rotation, curved path, or anything

between these two extremes) while the extra-retinal information indicates that no rotation has

occurred. We examined the possibility that adding retinal cues to disambiguate the flow field

would lead to a veridical percept. We explored two sets of cues: depth cues and 'two snapshot'

cues. 'Two snapshot' cues refer to changes in an object's retinal image that occur over time as

one moves with respect to the object. On theoretical grounds, one might expect improved

performance when depth information is added to the display (van den Berg & Brenner,

1994a). We examined this possibility by having observers indicate perceived self-motion

paths when the amount of depth information was varied. When stereoscopic cues and a variety

of monocular depth cues were added, observers still misperceived the depicted self-motion

when the rotational flow in the display was not accompanied by an appropriate extra-retinal,

eye-velocity signal. Specifically, they perceived curved self-motion paths with the curvature in

the direction of the simulated eye rotation. We then examined whether adding a road to the

scene--which provides several of these 'two snapshot' cues--helps observers determine the

correct self-motion path in the presence of simulated eye rotations. Performance improved

drastically in most observers with the road. Most observers have a dual percept, but with both

percepts available to them. By manipulating this road cue we showed that the longitudes/poles

intersection cue or changing intersection angle cue is salient enough to enable most observers

to accurately select the depicted linear path. Removing splay angle information from the road

displays did not affect performance. All of these cues require many frames because the

information they provide is only available over time; we showed that performance dropped

with decreasing trial duration. An analysis of many other 'two snapshot' cues shows they are

potentially useful for solving the rotation problem. (PsycINFO Database Record (c) 2002

APA, all rights reserved) Record 164 of 887 in PsycINFO 1999



Ehrlich, S. M., D. M. Beck, et al. (1998). “Depth information and perceived self-motion during

simulated gaze rotations.” Vision Research 38(20): 3129-3145.

When presented with random-dot displays wit little depth information, observers cannot

determine their direction of self-motion accurately in the presence of rotational flow without

appropriate extra-retinal information (Royden CS et al. Vis Res 1994;34:3197-214.). On

theoretical grounds, one might expect improved performance when depth information is added

to the display (van den Berg AV and Brenner E. Nature 1994;371:700-2). Pie examined this

possibility by having observers indicate perceived self-motion paths when the amount of depth

information was varied. When stereoscopic cues and a variety of monocular depth cues were

added, observers still misperceived the depicted self-motion when the rotational flow in the

display was not accompanied by an appropriate extra-retinal, eye-velocity signal. Specifically,

they perceived curved self-motion paths with the curvature in the direction of the simulated

eye rotation. The distance to the response marker was crucial to the objective measurement of

this misperception. When the marker distance was small, the observers' settings were

reasonably accurate despite the misperception of the depicted self-motion. When the marker

distance was large, the settings exhibited the errors reported previously by Royden CS et al.

Vis Res 1994,34:3197-3213. The path judgement errors observers make during simulated gaze

rotations appear to be the result of misattributing path-independent rotation to self-motion

along a circular path with path-dependent rotation. An analysis of the information an observer

could use to avoid such errors reveals that the addition of depth information is of little use. (C)

1998 Elsevier Science Ltd. All rights reserved.



Eizenman, M., C. A. Westall, et al. (1999). “Electrophysiological evidence of cortical fusion in

children with early-onset esotropia.” Investigative Ophthalmology & Visual Science 40(2):

354-362.

PURPOSE. TO investigate sensory fusion responses in infants and children with early-onset

esotropia to gain insights into the sequence of events that leads to strabismus.METHODS.

Sensory fusion was tested by measuring visual evoked potential (VEP) responses to dynamic

random dot correlograms (DRDCs) in a group of children (n = 23) with early-onset esotropia.

Thirteen children were tested before surgical alignment, and 13 children were tested after

surgical alignment (three children were tested before and after surgery). if the :angle of

strabismus was larger than 5 prism diopters, it n as corrected with Fresnel prisms (Fresnel

Prism and Lens, Scottsdale, AZ).RESULTS. Five (38%) of the IS children who n ere tested

before surgery showed detectable VEP responses to correlogram stimuli compared with 11

(85%) of the 13 children who were tested after surgical alignment. There n ere no significant

statistical differences between VEP responses to DRDCs from the postsurgery group and VEP

responses from an age-matched control group with normal binocular vision.CONCLUSIONS.

The presence of cortical sensory fusion in children with early-onset esotropia suggests that a

congenital defect of sensory fusion cannot be the root cause of esotropia in most children. The

data suggest that sensory fusion, when measured by VEP responses to DRDCs, is more robust

than stereopsis to abnormal binocular experience and support the notion that pathways

processing correlated/anticorrelated stimuli may not completely overlap with pathways

processing disparity information.



Ellemberg, D., T. L. Lewis, et al. (2002). “Better perception of global motion after monocular than

after binocular deprivation.” Vision Research 42(2): 169-179.

We used random-dot kinematograms to compare the effects of early monocular versus early

binocular deprivation on the development of the perception of the direction of global motion.

Patients had been visually deprived by a cataract in one or both eyes from birth or later after a

history of normal visual experience. The discrimination of direction or global motion was

significantly impaired after early visual deprivation. Surprisingly, impairments were

significantly worse after early binocular deprivation than after early monocular deprivation,

and the sensitive period was very short. The unexpectedly good results after monocular

deprivation suggest that the higher centers involved in the integration of global motion profit

from input to the nondeprived eye. These findings suggest that beyond the primary visual

cortex, competitive interactions between the eyes can give way to collaborative interactions

that enable a relative sparing of some visual functions after monocular deprivation. (C) 2002

Published by Elsevier Science Ltd.



Enright, J. T. (1984). “A New Random-Dot Stereo Illusion and Its Application to the Anstis-Howard-

Rogers Effect.” Perception 13(5): 547-553.



Erkelens, C. J. (1988). “Fusional Limits for a Large Random-Dot Stereogram.” Vision Research 28(2):

345-353.

Erkelens, C. J. (2001). “Organisation of signals involved in binocular perception and vergence control.”

Vision Research 41(25-26): 3497-3503.

A novel type of dynamic random-dot stereogram (DRS) was used to study vergence

movements and depth detection in response to temporal modulations of interocular

correlation. Each DRS consisted of the repeated presentation of a pair of correlated images

alternated by the presentation of a pair of uncorrelated images. The intervals of high (T.) and

low (T.) correlation varied from 14 to 224 ins in steps of 14 ins. Depth detection and vergence

responses behaved very different from each other as functions of T. and T,,. The different

behaviours suggest that depth and vergence most likely result from independent streams of

disparity processing. It is speculated that magnocellular layers process disparities that drive

vergence and that a parvocellular stream of disparity processing is involved in depth

perception. This suggestion is discussed in relation to recent findings on binocularly perceived

direction and depth. The discussion leads to suggesting a headcentric organisation of signals

involved in binocular perception and a retinal organisation of signals involved in vergence

control. (C) 2001 Elsevier Science Ltd. All rights reserved.



Erkelens, C. J. and H. Collewijn (1984). “Stereopsis, Vergence and Motion Perception During

Dichoptic Vision of Moving Random-Dot Stereograms.” Experientia 40(11): 1300-1301.



Erkelens, C. J. and H. Collewijn (1984). “Vergence Movements and Perception of Motion in Depth

During Dichoptic Vision of Moving Random-Dot Stereograms.” Perception 13(1): A20-A20.



Erkelens, C. J. and H. Collewijn (1985). “Eye movements and stereopsis during dichoptic viewing of

moving random-dot stereograms.” Vision Research 25(11): 1689-1700.

Studied the dynamic properties of the version and vergence system in relation to stereopsis for

movements of the whole visual scene. Large random-dot stereograms, moving laterally, were

viewed dichoptically by 4 human Ss without a fixed visual frame of reference. Sinusoidal

movements in counterphase of the 2 half-images constituting the stereogram induced

sinusoidal ocular vergence movements. The gain of vergence depended on the frequency as

well as the amplitude of stimulus movement, while the phase lag depended only on the

frequency. Fusion and stereopsis were retained up to a maximal velocity of change in relative

position of the 2 half-images between 6 and 13.5 degree/sec. Sinusoidal movement of 1 half-

image while the other one remained stationary induced sinusoidal ocular version as well as

vergence movements. At the retinal level, residual overall binocular disparities between the 2

half-images up to 2-degree arc were tolerated without loss of stereopsis. The presence of

sinusoidally varying overall binocular disparities and ocular vergence movements without

perception of motion in depth suggests that these variables are not adequate cues for

perception of (change in) depth. (34 ref) (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 658 of 887 in PsycINFO 1985-1987



Erkelens, C. J. and H. Collewijn (1985). “Eye-Movements and Stereopsis During Dichoptic Viewing of

Moving Random-Dot Stereograms.” Vision Research 25(11): 1689-1700.



Erkelens, C. J. and H. Collewijn (1985). “Eye-Movements in Relation to Loss and Regaining of Fusion

of Disjunctively Moving Random-Dot Stereograms.” Human Neurobiology 4(3): 181-188.



Erkelens, C. J. and H. Collewijn (1985). “Motion Perception During Dichoptic Viewing of Moving

Random-Dot Stereograms.” Vision Research 25(4): 583-588.



Erkelens, C. J. and W. A. Van de Grind (1994). “Binocular visual direction.” Vision Research 34(22):

2963-2969.

Examined whether the rules of cyclopean visual direction predict the percept of visual

direction for structured visual stimuli and how they are violated during viewing of structured

random-dot stereograms with different depth planes. Four Ss aligned a monocular/binocular

slider with a monocular/binocular test line present in the random-dot stereograms. Results

show that the rules of cyclopean direction can only be used for alignment of 2 binocularly

visible lines or 2 monocular lines presented to the same eye. Alignment in these cases is

predicted by almost any set of rules that transforms visible lines to a cyclopean eye. Stimulus

conditions, in which either 1 line is presented to 1 eye and the other line to the other eye or 1

line is presented to 1 eye and the other line to 2 eyes, provide a more critical test for validity of

the cyclopean rules. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record

423 of 887 in PsycINFO 1993-1995



Erkelens, C. J. and R. van Ee (1997). “Capture of the visual direction of monocular objects by adjacent

binocular objects.” Vision Research 37(13): 1735-1745.

Systematically varied the distance and disparity between binocular objects adjacent to a

monocular object and measured how the perceived direction of the monocular object

depended on these variables in 4 Ss. Ss viewed a large stereogram in which the half-images

oscillated in counterphase. Ss made considerable fixational errors in following the oscillations

of line and random-dot patterns. The results of the settings and of the retinal errors together

refute existing rules for binocular visual direction of monocular objects. Perceived directions

of monocular objects cannot be specified by geometrical rules that include only the positions

of the objects and of the 2 eyes. The results suggest that perceived directions of monocular

objects are captured by the binocular visual directions of adjacent binocular objects.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 265 of 887 in

PsycINFO 1996-1997



Erkelens, C. J. and R. van Ee (1998). “A computational model of depth perception based headcentric

disparity.” Vision Research 38(19): 2999-3018.

It is now well established that depth is coded by local horizontal disparity and global vertical

disparity. We present a computational model which explains how depth is extracted from

these two types of disparities. The model uses the two (one for each eye) headcentric

directions of binocular targets, derived from retinal signals and oculomotor signals.

Headcentric disparity is defined as the difference between headcentric directions of

corresponding features in the left and right eye's images. Using Helmholtz's coordinate

systems we decompose headcentric disparity into azimuthal and elevational disparity.

Elevational disparities of real objects are zero if the signals which contribute to headcentric

disparity do not contain any errors. Azimuthal headcentric disparity is a ID quantity from

which an exact equation relating distance and disparity can be derived. The equation is valid

for all headcentric directions and for all binocular fixation positions. Such an equation does

not exist if disparity is expressed in retinal coordinates. Possible types of errors in oculomotor

signals (six) produce global elevational disparity fields which are characterised by different

gradients in the azimuthal and elevational directions. Computations show that the elevational

disparity fields uniquely characterise both the type and size of the errors in oculomotor

signals. Our model uses a measure of the global elevational disparity field together with local

azimuthal disparity to accurately derive headcentric distance throughout the visual field. The

model explains existing data on whole-field disparity transformations as well as hitherto

unexplained aspects of stereoscopic depth perception. (C) 1998 Elsevier Science Ltd. All

rights reserved.



Erkelens, C. J. and W. A. Vandegrind (1994). “Binocular Visual Direction.” Vision Research 34(22):

2963-2969.

We examine whether the rules of cyclopean visual direction, as expressed by Hering and

others, correctly predict the percept of visual direction for structured visual stimuli.

Theoretical inspection of the rules of cyclopean visual direction shows a paradox for the

binocular visual directions of stimuli in which objects partly occlude each other. We

investigate how the rules of cyclopean direction are violated during viewing of structured

random-dot stereograms with different depth planes. The directions of monocular and

binocular visual elements are determined in an alignment task. Subjects align a

monocular/binocular slider with a monocular/binocular test line present in the random-dot

stereograms. The results show that the available rules of cyclopean direction are not sufficient

for human vision in this general situation. The available rules can only be used for alignment

of two binocularly visible lines or two monocular lines presented to the same eye. Alignment

in these cases is predicted by almost any set of rules that transforms visible lines to a

cyclopean eye. Stimulus conditions, in which either one line is presented to one eye and the

other line to the other eye or one line is presented to one eye and the other line to two eyes,

provide a more critical test for validity of the cyclopean rules. Our results show that the rules

of cyclopean direction fail to predict alignment precisely in these conditions. Inspection of the

data shows that binocular alignment is achieved by alignment of two monocular lines

presented to a single eye.



Erkelens, C. J. and R. VanEe (1997). “Capture of the visual direction of monocular objects by adjacent

binocular objects.” Vision Research 37(13): 1735-1745.

Investigations of binocular visual direction have concentrated mainly on stationary objects,

Eye positions were generally not measured and binocular fixation was assumed to be perfect,

During the viewing of stationary objects, vergence errors are not negligible but small, During

the viewing of moving objects, however, errors in binocular fixation are much larger, Existing

rules for binocular visual direction were examined under the latter, more demanding viewing

conditions, Eye movements were measured objectively by the scleral coil technique, Subjects

viewed a large stereogram in which the half-images oscillated in counterphase. The

stereogram contained two square random-dot patterns placed side by side with a gap in

between, A vertical line, visible only to one eye, oscillated in the gap, Subjects were asked to

adjust the amplitude of line motion until the line was perceived to be stationary, In so doing,

they set amplitudes equal to the amplitudes of half-image motion if the gap between the

patterns was narrow, They set amplitudes significantly smaller in wider gaps, Subjects made

considerable fixational errors in following the oscillations of the line and the random-dot

patterns, The results of the settings and of the retinal errors together refute existing rules for

binocular visual direction of monocular objects, Perceived directions of monocular objects

cannot be specified by geometrical rules that include only the positions of the objects and of

the two eyes, The results suggest that perceived directions of monocular objects are captured

by the binocular visual directions of adjacent binocular objects, Capture of binocular visual

direction was found to be effective for gaps as wide as 8 deg between the binocular objects,

The phenomenon of binocular capture has negative consequences for the general use of nonius

lines as indicators of eye position. (C) 1997 Elsevier Science Ltd.



Erkelens, C. J. and R. vanEe (1997). “Capture of visual direction: An unexpected phenomenon in

binocular vision.” Vision Research 37(9): 1193-1196.

Binocular perception of visual direction is based on laws which were formulated more than

100 years ago. These laws govern the directions in which human beings perceive objects

visible to both eyes (binocular objects) and objects visible to only one eye (monocular

objects). We report here that the laws do not hold for monocular objects adjacent to binocular

objects. The perceived directions of these monocular objects are captured by those of nearby

binocular objects. Capture of binocular visual direction is an unexpected phenomenon because

it refutes the generally accepted notion that a particular retinal location gives rise to a

particular subjective visual direction. The practical consequence is that the subjective

techniques for measuring eye position which are widely used in fundamental research and

clinical practice are unreliable if they are used in densely structured stimuli. We suggest that

capture results from a mechanism of lateral interaction between adjacent visual directions.

This mechanism ensures that, despite eye movements, objects have the same spatial order in

monocular and binocular vision. This conservation of spatial order also explains why retinal

blind spots are not manifest in binocular vision. (C) 1997 Elsevier Science Ltd.



Evans, C. S., P. Wenderoth, et al. (2000). “Detection of bilateral symmetry in complex biological

images.” Perception 29(1): 31-42.

The recognition of bilateral symmetry in simple dot patterns is reliably influenced by

orientation. Performance is best when the axis of symmetry is vertical. We conducted two

experiments to determine whether stimulus orientation also affects detection of the low levels

of naturally occurring asymmetry in complex biological images. University students judged

whether colour images displayed on a computer monitor possessed perfect bilateral symmetry.

Stimuli were generated from high-resolution plan-view images of crabs and insects. In

experiment 1, the asymmetric stimuli were the original animals, displayed on a standard black

background. Symmetrical versions of each natural image were generated by sectioning the

shape at the midline, copying and reflecting one side, and then fusing the two halves together.

To facilitate comparison of results with those obtained in earlier studies, we also presented dot

patterns based upon both the slightly asymmetric and perfectly symmetrical natural images.

Experiment 2 was designed to assess whether symmetry detection was dependent upon the

markings and patterns on the body and appendages of the animals. The natural images were

converted to silhouettes and tested against matched dot patterns. In both studies, images were

presented in a random sequence with the axis of symmetry vertical, horizontal, oblique left,

and oblique right. Performance with the biological images was consistently better than with

the dot patterns. Abolishing fine detail did not appreciably reduce this effect. A pronounced

vertical advantage was apparent with all stimuli, demonstrating that this phenomenon is robust

despite considerable variation in image complexity. The implications of orientation effects for

perception of natural structures are discussed.



Everatt, J., M. F. Bradshaw, et al. (1999). “Visual processing and dyslexia.” Perception 28(2): 243-254.

Examined the potential consequences of magnocellular-pathway deficits for dyslexics in a

comprehensive range of visual tasks. 16 dyslexics (aged 18-36 yrs) and 16 nondyslexics (aged

18-30 yrs) were compared on their ability to (1) perform vernier-acuity and orientation-acuity

tasks; (2) perceive motion by using a range of measures common in the psychophysical

literature; and (3) perceive shapes presented in random-dot stereograms at a range of disparity

pedestals, thereby dissociating stereopsis from vergence control. Results indicated no

significant differences in performance between the dyslexic and nondyslexic Ss in terms of the

visual-acuity measures. In general, dyslexics performed relatively poorly on measures of

motion perception and stereopsis, although when considered individually some of the

dyslexics performed better than some of the controls. The poor performance of the dyslexics

in the stereogram tasks was attributable to a subgroup of dyslexics who also appeared to have

severe difficulty with the motion-coherence task. These data are consistent with previous

evidence that some dyslexics may have deficits within the magnocellular visual pathway.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 197 of 887 in

PsycINFO 1999



Everett, J., M. F. Bradshaw, et al. (1999). “Visual processing and dyslexia.” Perception 28(2): 243-254.

Magnocellular-pathway deficits have been hypothesised to be responsible for the problems

experienced by dyslexic individuals in reading. However, research has yet to provide a

detailed account of the consequences of these deficits or to identify the behavioural link

between them and reading disabilities. The aim of the present study was to determine the

potential consequences of the magnocellular-pathway deficits for dyslexics in a

comprehensive range of visual tasks. Dyslexics and nondyslexics were compared on their

ability to (i) perform vernier-acuity and orientation-acuity tasks; (ii) perceive motion by using

a range of measures common in the psychophysical literature (D-min, D-max, and global

coherence); and (iii) perceive shapes presented in random-dot stereograms at a range of

disparity pedestals, thereby dissociating stereopsis from vergence control. The results

indicated no significant differences in performance between the dyslexic and nondyslexic

subjects in terms of the visual-acuity measures. In general, dyslexics performed relatively

poorly on measures of motion perception and stereopsis, although when considered

individually some of the dyslexics performed better than some of the controls. The poor

performance of the dyslexics in the stereogram tasks was attributable to a subgroup of

dyslexics who also appeared to have severe difficulty with the motion-coherence task. These

data are consistent with previous evidence that some dyslexics may have deficits within the

magnocellular visual pathway.



Fawcett, S., J. Leffler, et al. (2000). “Factors influencing stereoacuity in accommodative esotropia.”

Journal of Aapos 4(1): 15-20.

Purpose: Despite successful optical realignment, many children with accommodative esotropia

(ET) have abnormal stereoacuity. In a prospective study, we examined the influence of age of

onset, age at alignment, duration of constant misalignment, and accommodative

convergence/accommodation ratio on random dot stereoacuity outcomes in accommodative

ET Methods: Participants were 111 consecutive children with accommodative ET. Random

dot stereoacuity was measured using the Randot preschool stereoacuity test, the Randot

stereoacuity test, the infant random dot stereoacuity cards, and the Lang 1. Results: Age of

onset has only a minor influence on stereoacuity (P .10). Conclusions: Fine random dot stereoacuity is associated with

a constant misalignment of less than 4 months' duration. These findings promote prompt and

aggressive treatment of accommodative ET at the onset of intermittent or constant

misalignment.



Fawcett, S., J. E. Raymond, et al. (1998). “Anomalies of motion perception in infantile esotropia.”

Investigative Ophthalmology & Visual Science 39(5): 724-735.

PURPOSE. TO quantify motion sensitivity in patients with infantile esotropia who, as a

subgroup, have been previously reported to have abnormal oculomotor control. In addition, to

probe abnormal binocular development as a factor underlying abnormal motion perception in

infantile esotropia (IE), motion sensitivity was compared among participants with and without

stereopsis.METHODS. Monocular sensitivity to leftward and rightward motion was assessed

across the horizontal meridian, using partially coherent random dot kinematograms.

Participants included 11 observers with IE, 5 observers with acquired esotropial and 11

observers with normal eye alignment.RESULTS. Participants with IE showed no deficits in

motion sensitivity to any visual field locations when motion thresholds were collapsed across

direction. However, they showed an abnormal variation in directional anisotropy. Although

sensitivity to centripetal motion was superior in both hemifields of control participants and in

the temporal hemifields of participants with IE, a centrifugal bias was revealed in the nasal

hemifields of LE. Stereoblind observers with acquired esotropia showed a normal centripetal

directional anisotropy, whereas binocular observers with acquired esotropia showed

directional anisotropy similar to that in the IE group.CONCLUSIONS. Motion perception,

like oculomotor function in IE, is characterized by a variation of directional anisotropy for

stimuli presented to the nasal hemifields. This finding supports the hypothesis that abnormal

oculomotor control and motion perception in IE reflect a common disruption of the visual

system. A similar variation of directional sensitivity in patients with acquired esotropia with

normal stereopsis suggests that the interruption of binocularity is not the underlying cause of

abnormal motion perception in IE.



Fawcett, S. L. and E. E. Birch (2000). “Interobserver test-retest reliability of the randot preschool

stereoacuity test.” Journal of Aapos 4(6): 354-358.

Purpose: Random dot stereoacuity can be quantified to between 40 and 800 seconds of are in

preschool children by using the Randot Preschool Stereoacuity test (Stereo Optical Co, Inc,

Chicago, III). To incorporate this test into clinic and research settings, the reliability of its

stereoacuity scores obtained by separate examiners needs to be evaluated. The purpose of this

study was to evaluate its interobserver test-retest reliability. Methods: Participants included

102 consecutive children with binocular sensory function ranging from fine to no measurable

stereopsis. Clinical research participants included children with anomalous binocular vision

caused by strabismus, cataracts, anisometropia, and ptosis. In a prospective study, random dot

stereoacuity was measured twice under masked testing conditions by 2 examiners within a 1-

hour period. Results: Interobserver test-retest reliability of the Randot Preschool Stereoacuity

test is high among a population of children with diverse binocular sensory function. The

correlation coefficient between individual test scores was highly significant (r = 0.97, P.1). The upper and lower limits of agreement were

narrow, reflecting both the large sample size and the small variation between the 2 test scores.

Interobserver test-retest reliability of the Randot Preschool Stereoacuity test was nearly

constant across levels of functional stereoacuity, patient categorization, and age at the time of

the test. Conclusions: The high agreement between the Randot Preschool Stereoacuity test

scores by 2 independent observers supports its use in clinical management and research

settings for the quantitative assessment of binocular sensory vision, as well as in multicentered

research studies.



Fawcett, S. L. and E. E. Birch (2000). “Motion VEPs, stereopsis, and bifoveal fusion in children with

strabismus.” Investigative Ophthalmology & Visual Science 41(2): 411-416.

PURPOSE. The Link between nasal-temporal motion asymmetries and anomalous binocular

sensory function in infantile esotropia (Et) has led to the idea that visual evoked potential

responses to horizontal motion (mVEP) is an alternative measure of sensory binocularity to

stereopsis. A second hypothesis is that the mVEP response is a marker for bifoveal fusion. The

purpose of this study was to directly evaluate these two hypotheses by examining the

correspondence between the mVEP response and both stereoacuity and bifoveal fusion in a

cohort of strabismic patients with variable binocular sensory function.METHODS. Motion

VEPs, random dot stereopsis, and bifoveal fusion were measured in 94 children: 20 with

infantile ET, 16 with infantile accommodative ET, 22 with late-onset accommodative ET, 10

with intermittent infantile strabismus, and 26 normal control participants.RESULTS. Patients

with infantile ET and infantile accommodative ET had high concordance between mVEP

responses and stereoacuity and mVEP responses and bifoveal fusion. Asymmetric mVEP

responses were highly concordant with both no measurable stereopsis and an absence of

fusional vergence. Patients with late-onset accommodative ET and intermittent infantile

strabismus revealed discordance between the mVEP response and stereoacuity and high

concordance between the mVEP response and bifoveal fusion. Asymmetric mVEP responses

were highly concordant with the absence of bifoveal fusion and the minimum-size prism to

elicit fusional vergence.CONCLUSIONS. The qualitative and quantitative relationship

between the mVEP response and fusional vergence suggests that the mVEP response is an

objective measure of bifoveal fusion. The availability of such a test will facilitate studies of

normal development of bifoveal fusion and development of monofixation syndrome in

strabismus.



Fawcett, S. L. and E. E. Birch (2003). “Risk factors for abnormal binocular vision after successful

alignment of accommodative esotropia.” Journal of Aapos 7(4): 256-262.

Purpose: The purpose of this study was to identify clinical factors associated with abnormal

binocular vision outcomes among children with accommodative esotropia (ET) whose eyes

were successfully realigned with spectacles only or with spectacles and surgery. Methods. The

participants were 69 children with accommodative ET who were followed up prospectively

from the time of diagnosis. Clinical factors examined in this study included, high

accommodative convergence-to-accommodation (AC/A) relationship, high hyperopia,

anisometropia, age of onset, and duration of eye misalignment. Binocular vision was assessed

using measures of stereopsis, fusional vergence, sensory foveal fusion, and motion visual-

evoked potential (mVEP). Results. Children with a high AC/A relationship are 2.2 times more

likely to have an absence of fusional vergence than are children with a normal AC/A

relationship. Children having a duration of constant eye misalignment greater than or equal to

4 months before being successfully treated are 4.6 times more likely to have abnormal

stereopsis, 33 times more likely to have no stereopsis, 37 times more likely to have an absence

of fusional vergence, 31 times more likely to have an absence of sensory foveal fusion, and 17

times more likely to have an asymmetric mVEP response than children with a duration of

constant ET diagnosed at 0 to 3. months. Conclusions: Following successful eye alignment, as

many as 75% of patients with accommodative ET had anomalous binocular vision. A high

AC/A relationship poses a significant risk for abnormal fusional vergence only. A constant

eye misalignment lasting greater than or equal to 4 months poses a significant risk for

anomalous binocular vision on all measures studied.



Fawcett, S. L. and E. E. Birch (2003). “Validity of the titmus and randot circles tasks in children with

known binocular vision disorders.” Journal of Aapos 7(5): 333-338.

Purpose. The Titmus and Randot (version 2) circles tests contain monocular form cues that

may enable patients with binocular vision disorders to pass without any measurable stereopsis.

The purpose of this study was to evaluate the validity of the Randot and Titmus circles tests

for quantifying stereoacuity in children with known binocular vision disorders. Methods.

Participants included 170 consecutive children with diverse binocular sensory function

ranging from fine to no measurable stereopsis. Stereoacuity was measured using the Randot

circles, the Titmus circles, and the Randot Preschool Stereoacuity tests. Results: Discrepancies

between stereoacuity scores derived using either the Titmus or Randot circles tests and the

Randot Preschool Stereoacuity test increased as a function of random-dot stereoacuity.

Stereoacuity scores derived using the circles tests showed good agreement with random-dot

stereoacuity when stereoacuity was 2.2 log seconds of arc (160 seconds of arc) or better, but

they progressively overestimated stereoacuity for poorer random-dot stereoacuity scores.

Conclusion. When measuring stereoacuity using either the Titmus or Randot circles tests in

patients with known binocular vision disorders, stereoacuity scores > 2.2 log seconds of arc

should be interpreted with caution because it is above this level of stereoacuity that the

monocular form cues of each of the tests may invalidate the results.



Feher, A. and B. Julesz (2000). “Metatransparency: Simultaneous perception of two surfaces in an

Ambiguous Random Dot Stereogram.” Investigative Ophthalmology & Visual Science 41(4):

S735-S735.



Feldman, J. (2000). “Bias toward regular form in mental shape spaces.” Journal of Experimental

Psychology: Human Perception and Performance 26(1): 152-165.

The distribution of figural "goodness" in 2 mental shape spaces, the space of triangles and the

space of quadrilaterals, was examined. In Experiment 1, participants were asked to rate the

typicality of visually presented triangles and quadrilaterals (perceptual task). In Experiment 2,

participants were asked to draw triangles and quadrilaterals by hand (production task). The

rated typicality of a particular shape and the probability that that shape was generated by

participants were each plotted as a function of shape parameters, yielding estimates of the

subjective distribution of shape goodness in shape space. Compared with neutral distributions

of random shapes in the same shape spaces, these distributions showed a marked bias toward

regular forms (equilateral triangles and squares). Such psychologically modal shapes

apparently represent ideal forms that maximize the perceptual preference for regularity and

symmetry.



Fender, D. and B. Julesz (1967). “Extension of Panum's Fusional Area in Binocularly Stabilized

Vision.” Journal of the Optical Society of America 57(6): 819-830.

A NOVEL PHENOMENON IN STEREOPSIS CAN BE OBSERVED WHEN VIEWING

BINOCULARLY STABILIZED RETINAL IMAGES. THIS PHENOMENON IS

PARTICULARLY IMPRESSIVE FOR RANDOM-DOT STEREOSCOPIC IMAGES IN

FOVEAL VISION. IF INITIALLY THE LEFT AND RIGHT IMAGES ARE BROUGHT

WITHIN PANUM'S FUSIONAL AREA (6-MIN ARC ALIGNMENT), FUSION AND

STEREOPSIS ARE PERCEIVED; THE IMAGES CAN THEN BE PULLED APART

SYMMETRICALLY BY ABOUT 2DEGREES IN THE HORIZONTAL DIRECTION

WITHOUT LOSS OF STEREOPSIS OR FUSION. THE IMAGES ARE ACTUALLY

PULLED APART ON THE RETINAE, SINCE THE BINOCULAR RETINAL

STABILIZATION COMPENSATES FOR THE CONVERGENCE-DIVERGENCE

MOTIONS OF THE EYES; HENCE A SUPRARETINAL FUNCTION MUST BE

RESPONSIBLE FOR THIS TYPE OF FUSION. IF THE PULLING PROCEEDS TOO

FAST, OR EXCEEDS THE 2DEGREES LIMIT, OR IF THE STIMULUS IS OCCLUDED

BRIEFLY, THE FUSIONAL MECHANISM FAILS AND THE FUSED IMAGE

ABRUPTLY BREAKS APART INTO 2 SEPARATE IMAGES WHICH HAVE TO BE

BROUGHT WITHIN PANUM'S AREA AGAIN TO REESTABLISH FUSION. FOR LINE

STIMULI, THE MAXIMUM DISPARITY WITHOUT LOSS OF FUSION IS MUCH LESS

THAN FOR RANDOM-DOT PATTERNS; IT IS ALWAYS LARGEST FOR DISPARITY

IN THE HORIZONTAL DIRECTION AND IS LESS IN THE VERTICAL DIRECTION.

THESE FINDINGS INDICATE THAT STEREOPSIS AND THE CLASSICALLY

CONCEIVED CORRESPONDING POINTS GREATLY DEPEND BOTH ON THE CLASS

OF STIMULUS USED AND ON THE RECENT HISTORY OF THE STIMULATION.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 883 of 887 in

PsycINFO 1872-1966



Fenelon, B., R. A. Neill, et al. (1984). “Stereoscopic cerebral evoked potentials of Air Force pilots and

civilian comparison groups.” Aviation, Space, and Environmental Medicine 55(10): 914-920.

Reports the investigative application of a new type of random-dot stereogram (RDS) unit,

including a generating and display system, in the measurement of stereopsis. The dynamic

RDSs were presented to 14 Air Force jet pilots (aged 21-38 yrs) through a new visual display

system. Games that simulated target-detection exercises were included in the test sequence. A

pattern of response was revealed in the event-related potential measures. In general, left-

hemisphere amplitudes exceeded those of the right hemisphere, and the predominant response

was recorded at the left-temporal site. Amplitudes of responses in Ss able to describe the

stimuli in subjective report (perceivers) exceeded those of nonperceivers. Stimuli with definite

boundaries evoked stronger and earlier-latency responses than stimuli with nebulous

boundaries. (16 ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record

699 of 887 in PsycINFO 1978-1984



Fenelon, B., R. A. Neill, et al. (1986). “Evoked-Potentials to Dynamic Random Dot Stereograms in

Upper, Center and Lower Fields.” Documenta Ophthalmologica 63(2): 151-156.



Feresin, C. and I. P. Howard (1994). “"Shear" verticali, orizzontali e percezione stereoscopica di

superfici inclinate. / Vertical and horizontal "shear" and stereoscopic perception of inclined

surfaces.” Giornale Italiano di Psicologia 21(4): 665-683.

Studied the association among perception of inclined surfaces and horizontal or vertical shear

transformations of the inclination. Human Ss: Six normal Italian adults (aged 26-65 yrs)

(right-handed). Ss were presented with stereoscopic images of random-dot inclined ramp

surfaces that differed according to horizontal or vertical shear transformations. Ss were asked

to indicate if there was a deviation between the 2 images and the degree of deviation. The

results were evaluated according to degree of perceived disparity, actual disparity, and type of

shear transformation. An ANOVA and other statistical tests were used. (English abstract)

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 397 of 887 in

PsycINFO 1993-1995



Feresin, C. and I. P. Howard (1995). “Disparita verticali e movimenti oculari di ciclovergenza nella

percezione stereoscopica di superfici inclinate. / Vertical disparity and ocular movements of

cyclovergence in the stereoscopic perception of slanted surfaces.” Giornale Italiano di

Psicologia 22(5): 733-755.

Studied the stereoscopically perceived induced inclination of a luminous vertical line that was

superimposed on random-dot ramp surfaces connected by a horizontal and a vertical shear

transformation. Human Ss: Six normal Italians. Each S viewed 15 random-dot stereograms.

Torsional eye movements were measured, and the role of human cyclovergence in the

transformation of vertical disparities into horizontal disparities was assessed. (English

abstract) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 387 of 887 in

PsycINFO 1993-1995



Fern, K. D., R. E. Manny, et al. (1998). “Screening for anisometropia in preschool children.”

Optometry and Vision Science 75(6): 407-423.

Purpose. A preschool vision screening program was reviewed to evaluate eccentric

photoscreening (EP), visual acuity, and stereopsis in identifying anisometropia, Methods.

Patients referred by the screening were examined to assess efficacy of the three screening

techniques in a population of preschool children. Testability and comparison of screening

results to the classification of anisometropia (greater than or equal to 1 D) by retinoscopy

obtained during a complete examination were evaluated. Results. Although EP identified

94.5% of the anisometropic children as abnormal, only 27.8% were classified as

anisometropic by EP. Of the anisometropic children, 36.1% failed acuity, but only 19.4%

failed based on a 2 line or greater interocular acuity difference. Stereopsis correctly identified

only 7.3% of anisometropes as abnormal. Conclusions. The sensitivity of EP in identifying

anisometropic children as abnormal was superior to acuity and stereopsis, yet its ability to

identify anisometropia specifically was poor. Anisometropia of low magnitude or that masked

by the dead zone of the EP system was frequently classified as isometropic. Altering the EP

referral criterion and/or taking photographs through adequate power plus lenses may improve

the sensitivity for specifically identifying anisometropia, However, caution must be exercised

when using EP to examine the prevalence of anisometropia in a population or if used to screen

for only amblyogenic refractive errors (i.e., anisometropia), because many anisometropes will

be missed, resulting in inaccurate prevalence data and significant underreferrals.



Festa, E. K. and L. Welch (1997). “Recruitment mechanisms in speed and fine-direction discrimination

tasks.” Vision Research 37(22): 3129-3143.

The minimum information necessary to specify motion requires a change in position across

time. Previous studies have shown that human motion measurements improve with more than

two frames of motion. This study clarifies how motion information is integrated to produce the

best speed and direction discrimination. Using random-dot kinematograms, fine-direction

discrimination thresholds and speed discrimination thresholds are assessed as a function of dot

lifetime. Specifically, we ask if performance on both tasks: depends on dot lifetime in the

same manner. If both speed and direction discrimination performance improve the same way

with increasing dot lifetime, this would indicate that both tasks have the same integration limit

and both tasks may depend on the same underlying mechanisms. Experiment 1 shows that for

both tasks a four-frame dot lifetime is necessary for observers to reach asymptotic threshold

levels. The absolute level of performance improves with increasing stimulus duration or

signal-to-noise ratio, but the integration limit itself does not vary. Experiment 2 examines

whether this integration limit is constrained by the number of frames or by the temporal

duration of the dot lifetime. The data in Experiment 2 suggest that both a minimum number of

samples and a minimal temporal integration period determine the integration limit for

recruitment mechanisms. The results suggest that speed and fine-direction discrimination

depend upon the same underlying motion mechanisms. These results are discussed in relation

to possible underlying physiological substrates and computational models of motion

measurement. (C) 1997 Elsevier Science Ltd.



Field, D. J., A. Hayes, et al. (1993). “Contour integration by the human visual system: Evidence for a

local "association field.".” Vision Research 33(2): 173-193.

Examined how continuity may be represented by a visual system that filters spatial data using

arrays of cells selective for orientation and spatial frequency. It is possible to take advantage

of the redundancy in continuous, but nonaligned features by associating the outputs of filters

with similar tuning. Five experiments were performed to determine the rules that govern the

perception of continuity. Ss were presented with arrays of oriented, band-pass elements

(Gabor patches) in which a subset of the elements was aligned along a "jagged" path. Ss were

able to identify the path within a field of randomly oriented elements even when the spacing

between the elements was larger than the size of any of the individual elements. Results are

discussed in terms of an association field that integrates information across neighboring filters

tuned to similar orientations.



Finch, A. M., R. C. Wilson, et al. (1997). “Matching Delaunay graphs.” Pattern Recognition 30(1):

123-140.

This paper describes a Bayesian framework for matching Delaunay triangulations. Relational

structures of this sort are ubiquitous in intermediate level computer vision, being used to

represent both Voronoi tessellations of the image plane and volumetric surface data. Our

matching process is realised in terms of probabilistic relaxation. The novelty of our method

stems from its use of a support function specified in terms of face-units of the graphs under

match. In this way, we draw on more expressive constraints than is possible at the level of

edge-units alone. In order to apply this new relaxation process to the matching of realistic

imagery requires a model of the compatibility between faces of the data and model graphs. We

present a particularly simple compatibility model that is entirely devoid of free parameters. It

requires only knowledge of the numbers of nodes, edges and faces in the model graph. The

resulting matching scheme is evaluated on radar images and compared with its edge-based

counterpart. We establish the operational limits and noise sensitivity on the matching of

random-dot patterns. Copyright (C) 1996 Pattern Recognition Society.



Fineman, M. B. (1971). “Facilitation of stereoscopic depth perception by a relative-size cue in

ambiguous disparity stereograms.” Journal of Experimental Psychology 90(2): 215-221.

Proposed that the cue of relative size may facilitate depth perception in accordance with a

crossed or uncrossed disparity in stereograms in which both tendencies are equally

represented. A concurrent concept was that the latency associated with the perception of depth

in random-dot stereograms may be due, in part, to a cue conflict between binocular disparity

and relative size. 4 male and 2 female graduate students were given 8 presentations of 5

stereographic stimuli, in which disparity was ambiguous but relative size was systematically

altered. Ss were tested for direction of depth preferences and response latency. Both the

relative-size effects and an uncrossed disparity bias were evidenced in the data. The latter

effect was attributed to binocular rivalry between dissimilar elements in the stereoscopic half-

fields. It is concluded that depth cue relationships are more complex than had been suggested

by simple dominance theories. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 873 of 887 in PsycINFO 1967-1977

Finlay, D. C., M. L. Manning, et al. (1989). “Difficulties in the Definition of Stereoscotoma Using

Temporal Detection of Thresholds of Dynamic Random Dot Stereograms.” Documenta

Ophthalmologica 72(2): 161-173.



Finlay, D. C., M. L. Manning, et al. (1987). “Effects of movement in the background field on long-

range apparent motion.” Vision Research 27(9): 1679-1682.

Conducted 2 experiments using time-till-breakdown as a measure of apparent motion (AM) in

22 untrained Ss. In Exp I, centrally viewed dynamic random dot stereograms and nondisparate

stimuli in dynamic random dot fields yielded higher optimal frequencies than did a standard

binocular condition. In Exp II, a higher optimal frequency was observed for disparate dynamic

random dot stimuli compared with both standard binocular and nondisparate stimuli presented

on a static random dot field. Interaction between short- and long-range AM processes is

considered in the interpretation of findings. (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 628 of 887 in PsycINFO 1985-1987



Fleet, D. J., H. Wagner, et al. (1996). “Neural encoding of binocular disparity: Energy models, position

shifts and phase shifts.” Vision Research 36(12): 1839-1857.

Neurophysiological data support two models for the disparity selectivity of binocular simple

and complex cells in primary visual cortex. These involve binocular combinations of

monocular receptive fields that are shifted in retinal position (the position-shift model) or in

phase (the phase-shift model) between the two eyes. This article presents a formal description

and analysis of a binocular energy model with these forms of disparity selectivity. We propose

how one might measure the relative contributions of phase and position shifts in simple and

complex cells. The analysis also reveals ambiguities in disparity encoding that are inherent in

these model neurons, suggesting a need for a second stage of processing. We propose that

linear pooling of the binocular responses across orientations and scales (spatial frequency) is

capable of producing an unambiguous representation of disparity. Copyright (C) 1996 Elsevier

Science Ltd.



Fletcher, J. M. (1985). “Memory for verbal and nonverbal stimuli in learning disability subgroups:

Analysis by selective reminding.” Journal of Experimental Child Psychology 40(2): 244-259.

Evaluated memory for verbal and nonverbal stimuli, using selective reminding procedures in

92-144 mo old normal achieving children and disabled learners. Disabled learners were placed

in 1 of 4 groups depending on their pattern of Wide Range Achievement Test scores: 10

reading-spelling disabled (R-S), 38 reading-spelling-arithmetic disabled (R-S-A), 10 spelling-

arithmetic disabled (S-A), and 13 arithmetic disabled (A). 16 controls also participated. Each

S received 2 analogous free-list memory tasks, one for verbal material (animal names) and the

other for nonverbal material (random dot patterns). These tasks were administered using

selective reminding procedures that permitted separation of storage and retrieval aspects of

memory by reminding Ss only of those words not recalled on previous trials. Results reveal

that relative to controls, the A and S-A Ss had significantly lower storage and retrieval scores

on the nonverbal task but did not differ on the verbal task. The R-S Ss differed only on

retrieval scores from the verbal task. The R-S-A Ss differed on retrieval scores on the verbal

task and storage and retrieval scores on the nonverbal task. Results provide external validation

for the classification of disabled learners according to patterns of academic achievement,

demonstrating a useful procedure for dealing with the intra-S variability characteristic of

disabled learners. (31 ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 677 of 887 in PsycINFO 1985-1987



Ford, J. M., A. Pfefferbaum, et al. (1982). “Effects of perceptual and cognitive difficulty on P3 and RT

in young and old adults.” Electroencephalography and Clinical Neurophysiology 54(3): 311-

321.

10 elderly (mean age 79 yrs) and 10 young (mean age 23 yrs) females received a series of

trials in a memory retrieval task. On each trial, Ss saw a memory set of 2 or 4 digits followed

by a probe. The task was to indicate whether the probe was a positive or negative instance

(response type) of the memory set for that trial. On half the trials, the probe digits were

degraded by a mask of random dots (stimulus quality). For both young and old Ss, RT was

later to probes following the larger set size, later to degraded probes, and later to negative

probes. For young Ss, P3 latency in the elderly responded quite differently: It was unaffected

by set size or response type. However, P3 was somewhat delayed by the degraded probes,

suggesting that the failure to reflect set size or response type was not due to a simple latency

ceiling effect in the elderly. The correlation between single-trial P3 latency and RT in the

elderly was lower than in the young. Findings are discussed in terms of age-related differences

in the meaning of P3 latency. (French abstract) (17 ref) (PsycINFO Database Record (c) 2002

APA, all rights reserved) Record 739 of 887 in PsycINFO 1978-1984



Fortin, A., J. Faubert, et al. (2003). “Stereoscopic processing in the human brain as a function of

binocular luminance rivalry.” Neuroreport 14(8): 1163-1166.

We investigated the neural substrates of a recent model of human stereodepth perception by

obtaining measurements of regional cerebral blood flow (rCBF) using PET Subjects

experienced the perceptual properties of stereopsis by viewing rival-luminance stereograms

displaying an identical random-dot pattern in their central portion while the backgrounds

exhibited correspondent dots contrasting in black/white luminance. The stereoscopic vision

induced by retinal luminance rivalry coincided with a significant elevation of rCBF in the

dorsal visual pathway. Area V5 (MT) was activated bilaterally by the experimental condition

while the remaining active loci were restricted to the right hemisphere. The neural sites that

responded to this novel stereoscopic stimulus are similar to those activated by traditional

stereograms containing horizontal disparities.



Fortin, A., A. Ptito, et al. (2002). “Cortical areas mediating stereopsis in the human brain: a PET

study.” Neuroreport 13(6): 895-898.

Using PET, we investigated the neural substrates of stereodepth perception in humans. The

presentation of Julesz-type random-dot stereograms (RDS) produced significant rCBF

elevations in Brodmann areas (BA) 18,19 and 7, all in the right hemisphere. Activation foci

were also found in both middle temporal areas (MT). These results demonstrate that, as in

primates, cortical area MT and extrastriate areas are central to stereovision and that a network

of predominant right hemispheric regions is recruited to meet visuo-spatial processing

demands associated with horizontal binocular disparity inputs. NeuroReport 13:895-898 (C)

2002 Lippincott Williams Wilkins.



Foster, D. H. (1978). “Visual comparison of random-dot patterns: Evidence concerning a fixed visual

association between features and feature-relations.” Quarterly Journal of Experimental

Psychology 30(4): 637-654.

48 male undergraduates made same-different judgments on pairs of briefly presented random-

dot patterns: they had to judge in separate experiments either whether the members of each

pair were identical in shape or whether the number of dots in each pattern was the same. When

1 pattern was the rotated version of the other, the proportion of same responses varied with the

angle of rotation in the same way for the 2 types of judgment. From these and other data

obtained with pattern pairs in which members differed in shape and in dot number, the

following inferences are made: (a) In making both kinds of same judgments, a fixed visual

association is established between local features (dot clusters within the pattern) and certain

spatial relations between these local features. Thus when spatial-relation information is

irrelevant to the pattern-comparison task, as in judgments of dot number, this information is

not separated from the relevant local-feature information in the pattern representation. (b) In

both tasks, a common description of the patterns in terms of local features and feature-

relations is used in making a same judgment. (c) Some shape discrimination independent of

orientation and some dot-number discrimination independent of shape are each the result of

the process mediating different decisions. (31 ref) (PsycINFO Database Record (c) 2002 APA,

all rights reserved) Record 800 of 887 in PsycINFO 1978-1984



Foster, D. H., J. Thorson, et al. (1981). “The fine-grain movement illusion: A perceptual probe of

neuronal connectivity in the human visual system.” Vision Research 21(7): 1123-1128.

In the visual periphery, brief presentation of 2 very closely spaced luminous point stimuli, in

rapid sequence, causes the illusory impression that a single dot moves over a path of

considerable extent. In 3 Ss, the interactions obtainable between 2 illusions near each other are

described for various configurations of the inducing stimuli. Only when such illusions are

codirectional are they found not to interfere with each other. The effective field position and

extent of the illusion were measured by pitting 2 suitably separated illusions against each

other. The extent varies from about 2| to 6| as stimulus eccentricity is increased from 10| to

24|. However, when mapped onto visual cortex by means of human cortical magnification

factor, the illusion spans a patch of cortex about 3 mm in diameter, regardless of stimulus

eccentricity. Such a region in primate visual cortex corresponds approximately to the locus of

cortical cells that "see" a given retinal point. It is suggested that these fine-grain effects may

underlie certain perceptual responses to sequential random-dot displays. (20 ref) (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 751 of 887 in PsycINFO 1978-

1984



Fredericksen, R. E., F. A. J. Verstraten, et al. (1994). “Temporal integration of random dot apparent

motion information in human central vision.” Vision Research 34(4): 461-476.

Human motion perception is assumed to be functionally described by an array of bilocal

detectors feeding later, higher order computational stages. Using this model as a guide, the

study measured improvement of spatio-temporal displacement sensitivity by temporal

integration (summation) in the central vision of 3 experienced observers, using random dot

pattern apparent-motion stimuli. Results agree with experiments by R. J. Snowden and O. J.

Braddick (see PA, Vol 77:13852 and 11442; and 78:3323) with regard to improvement of

maximum perceivable spatial displacement (PSD), but show that the minimum PSD can be

improved in a similar manner. Further, stimulus duration is a more accurate predictor of

sensitivity than the number of frames in the stimulus over a wide range of stimulus parameter

values. Finally, results indicate that temporal tuning of motion detectors is inversely related to

the size of the spatial pattern displacement. (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 454 of 887 in PsycINFO 1993-1995



Fredericksen, R. E., F. A. J. Verstraten, et al. (1993). “Spatiotemporal Characteristics of Human

Motion Perception.” Vision Research 33(9): 1193-1205.

A bi-local detector array model was assumed to describe the functional performance of

monocular motion perception. Distributions of model parameters were measured in human

vision at several positions in the visual field. The stimulus paradigm was designed to measure

directional motion perception thresholds for individual combinations of spatial displacement

and temporal delay in random dot apparent motion stimuli. The resulting data support

previous results on perceivable spatial displacement limits in human vision but also indicate

that both minimum and maximum perceivable spatial displacement thresholds in human

observers have a similar dependence on temporal delay. This dependence changes with

eccentricity in the visual field in a qualitatively similar manner but by quantitatively different

factors. A description of possible biological properties of the bi-local detector population is

presented that may explain how detection of spatio-temporal pattern displacements can be

performed by a single system. Such a system also predicts that minimum and maximum

perceivable spatial displacement thresholds should scale with visual field eccentricity in a

manner consistent with our results.



Fredericksen, R. E., F. A. J. Verstraten, et al. (1994). “Spatial Summation and Its Interaction with the

Temporal Integration Mechanism in Human Motion Perception.” Vision Research 34(23):

3171-3188.

The combination of visual motion information over visual space (spatial summation) and

stimulus duration (temporal integration) was investigated using a random-pixel array

(spatiotemporally broad-band) apparent motion stimulus designed to isolate specific

populations of visual motion detectors. The results indicate that, in agreement with results

from spatiotemporally narrow-band stimuli, spatial summation follows the form of linear

probabilistic summation rather than non-linear probabilistic summation. Linear probabilistic

summation holds for a wide range of stimulus parameters and when changing either motion

stimulus height or width. Linear probabilistic summation breaks down when the motion

display region approaches a height and/or width that is related to the spatial displacement size,

not the speed, of the random-pixel array. This height and width (termed the critical height and

width, or critical dimension), increases with spatial displacement size and can be interpreted as

a measure of the basic dimensions of the selected motion detector population's receptive field.

The critical height is smaller than the critical width, a result that is consistent with a motion

detector receptive field that is elongated in the direction of motion. Perhaps most importantly,

the mechanisms of temporal integration and spatial summation can work independently under

a wide range of conditions. Finally, the results provide evidence for a short-term inhibitory

phenomenon from the edges of the useful display area that affects the visibility of the motion.

Fredericksen, R. E., F. A. J. Verstraten, et al. (1994). “Temporal Integration of Random-Dot Apparent

Motion Information in Human Central Vision.” Vision Research 34(4): 461-476.

Human motion perception is assumed to be functionally described by an array of bi-local

detectors feeding later, higher order computational stages. Using this model as a guide,

improvement of spatio-temporal displacement sensitivity by temporal integration (summation)

was measured in human central vision using random dot pattern apparent-motion stimuli. Our

results agree with previous experiments with regard to improvement of. maximum perceivable

spatial displacement but show that contrary to previous results the minimum perceivable

spatial displacement can be improved in a similar manner. Furthermore, stimulus duration is a

more accurate predictor of sensitivity than the number of frames in the stimulus over a wide

range of stimulus parameter values. Finally, our results indicate that temporal tuning of motion

detectors is inversely related to the size of the spatial pattern displacement.



Fredericksen, R. E., F. A. J. Verstraten, et al. (1997). “Pitfalls in estimating motion detector receptive

field geometry.” Vision Research 37(1): 99-119.

A number of psychophysical investigations have used spatial-summation methods to estimate

the receptive field (RF) geometry of motion detectors by exploring how psychophysical

thresholds change with stimulus height and/or width, This approach is based on the idea that

an observer's ability to detect motion direction is strongly determined by the relationship

between the stimulus geometry (height and width) and the RF of the activated motion

detectors. Our results show that previous estimates of RF geometry can depend significantly

on stimulus position in the visual field as well as on the stimulus height-to-width ratio, The

data further show that RF estimates depend on the stimulus in a manner that is inconsistent

with basic predictions derived from current motion detector models, Hence previous estimates

of height, width, and height-to-width ratios of motion detector RFs are inaccurate and

unreliable, This inaccurac/unreliability is attributed to a number of sources, These include

incorrect fixed-parameter values in model fits, as well as the confounding of physiological

spatial summation area through combined use of contrast thresholds and Gaussian-windowed

stimuli, A third source of error is an asymmetric variation of spatiotemporal correlation in the

stimulus as either its height or width is varied (and the other dimension held constant), Most

importantly, a fourth source of unreliability is attributed to the existence of a nonlinear,

nonmonotonic distribution of motion detectors in the visual field that has been previously

described and is a natural result of visual anatomy. Copyright (C) 1996 Elsevier Science Ltd



Freeman, T. C. A., M. G. Harris, et al. (1996). “On the relationship between deformation and perceived

surface slant.” Vision Research 36(2): 317-322.

A compelling impression of surface slant is produced by random dot displays depicting

deformation and translation alone. A simple model of slant estimation based upon deformation

is shown to capture quantitatively both the perceived slant in this situation and the distortion

in perceived slant produced when constant deformation is added to random dot displays

depicting moving slanted surfaces, The results confirm that deformation provides a simple

account of perceived slant.



Freeman, T. C. A., M. G. Harris, et al. (1994). “Human Sensitivity to Temporal Proximity - the Role of

Spatial and Temporal Speed Gradients.” Perception & Psychophysics 55(6): 689-699.

Estimates of temporal proximity (sometimes called time-to-collision) from random-dot flow

patterns are shown to be based upon retinal speed, rather than upon changes in dot density.

Neither the spatial nor the temporal gradient of motion is essential to the task, but estimates

can be made from either alone. Performance is unaffected by the addition of rotational motion,

suggesting that observers are capable of extracting the radial component of motion, which

contains all the relevant information, from complex stimuli.



Freeman, T. C. A., M. G. Harris, et al. (1994). “Human sensitivity to temporal proximity: The role of

spatial and temporal speed gradients.” Perception and Psychophysics 55(6): 689-699.

In 4 experiments, 2 observers assessed temporal proximity based on retinal flow. Exp 1

estimated sensitivity to temporal proximity. Exp 2 manipulated space and time gradients to

evaluate which aspects of the stimulus were important to the task. Exp 3 observed the role of

speed gradients and manipulation of cues provided by changes in dot density and average

speed. Exp 4 estimated temporal proximity with rotational masks at a range of amplitudes.

Estimates of temporal proximity or time-to-collision from random-dot flow patterns were

shown to be based on retinal speed rather than on changes in dot density. Neither the spatial

nor the temporal gradient of motion was essential to the task, but estimates can be made from

either alone. Performance was unaffected by the addition of rotational motion, suggesting that

observers were capable of extracting the radial component of motion, which contains all the

relevant information, from complex stimuli. (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 439 of 887 in PsycINFO 1993-1995



Freeman, T. C. A. and J. H. Sumnall (2002). “Motion versus position in the perception of head-centred

movement.” Perception 31(5): 603-615.

Observers can recover motion with respect to the head during an eye movement by comparing

signals encoding retinal motion and the velocity of pursuit. Evidently there is a mismatch

between these signals because perceived head-centred motion is not always veridical. One

example is the Filehne illusion, in which a stationary object appears to move in the opposite

direction to pursuit. Like the motion aftereffect, the phenomenal experience of the Filehne

illusion is one in which the stimulus moves but does not seem to go anywhere. This raises

problems when measuring the illusion by motion nulling because the more traditional

technique confounds perceived motion with changes in perceived position. We devised a new

nulling technique using global-motion stimuli that degraded familiar position cues but

preserved cues to motion. Stimuli consisted of random-dot patterns comprising signal and

noise dots that moved at the same retinal 'base' speed. Noise moved in random directions. In

an eye-stationary speed-matching experiment we found noise slowed perceived retinal speed

as 'coherence strength' (ie percentage of signal) was reduced. The effect occurred over the

two-octave range of base speeds studied and well above direction threshold. When the same

stimuli were combined with pursuit, observers were able to null the Filehne illusion by

adjusting coherence. A power law relating coherence to retinal base speed fit the data well

with a negative exponent. Eye-movement recordings showed that pursuit was quite accurate.

We then tested the hypothesis that the stimuli found at the null-points appeared to move at the

same retinal speed. Two observers supported the hypothesis, a third partially, and a fourth

showed a small linear trend. In addition, the retinal speed found by the traditional Filehne

technique was similar to the matches obtained with the global-motion stimuli. The results

provide support for the idea that speed is the critical cue in head-centred motion perception.



Freitag, P., M. W. Greenlee, et al. (1998). “Effect of eye movements on the magnitude of functional

magnetic resonance imaging responses in extrastriate cortex during visual motion perception.”

Experimental Brain Research 119(4): 409-414.

We have studied the effects of pursuit eye movements on the functional magnetic resonance

imaging (fMRI) responses in extrastriate visual areas during visual motion perception.

Echoplanar imaging of 10-12 image planes through visual cortex was acquired in nine subjects

while they viewed sequences of random-dot motion. Images obtained during stimulation

periods were compared with baseline images, where subjects viewed a blank field. In a

subsidiary experiment, responses to moving dots, viewed under conditions of fixation or

pursuit, were compared with those evoked by static dots. Eye movements were recorded with

MR-compatible electro-oculographic (EOG) electrodes. Our findings show an enhanced level

of activation (as indexed by blood-oxygen level-dependent contrast) during pursuit compared

with fixation in two extrastriate areas. The results support earlier findings on a motion-specific

area in lateral occipitotemporal cortex (human V5). They also point to a further site of

activation in a region approximately 12 mm dorsal of V5. The fMRI response in V5 during

pursuit is significantly enhanced. This increased response may represent additional processing

demands required for the control of eye movements.



Freitag, P., M. W. Greenlee, et al. (2001). “fMRI response during visual motion stimulation in patients

with late whiplash syndrome.” Neurorehabilitation and Neural Repair 15(1): 31-37.

After whiplash trauma, up to one fourth of patients develop chronic symptoms including head

and neck pain and cognitive disturbances. Resting perfusion single-photon-emission computed

tomography (SPECT) found decreased temporoparietooccipital tracer uptake among these

long-term symptomatic patients with late whiplash syndrome. As MT/MST (V5/V5a) are

located in that area, this study addressed the question whether these patients show

impairments in visual motion perception. We examined five symptomatic patients with late

whiplash syndrome, five asymptomatic patients after whiplash trauma, and a control group of

seven volunteers without the history of trauma. Tests for visual motion perception and

functional magnetic resonance imaging (fMRI) measurements during visual motion

stimulation were performed. Symptomatic patients showed a significant reduction in their

ability to perceive coherent visual motion compared with controls, whereas the asymptomatic

patients did not show this effect. fMRI activation was similar during random dot motion in all

three groups, but was significantly decreased during coherent dot motion in the symptomatic

patients compared with the other two groups. Reduced psychophysical motion performance

and reduced fMRI responses in symptomatic patients with late whiplash syndrome both point

to a functional impairment in cortical areas sensitive to coherent motion. Larger studies are

needed to confirm these clinical and functional imaging results to provide a possible additional

diagnostic criterion for the evaluation of patients with late whiplash syndrome.



French, R. S. (1953). “The discrimination of dot patterns as a function of number of dots and average

separation of dots.” Journal of Experimental Psychology 46(1): 1-9.



French, R. S. (1954). “Identification of dot patterns from memory as a function of complexity.” Journal

of Experimental Psychology 47: 22-26.

Ss learned an arbitrary city name for each of 12 random dot patterns representing the possible

appearance of these cities on a radar scope. The Ss were divided into 12 groups such that the

number of dots in the patterns was varied from 1 to 12 for the independent groups of Ss as a

means of varying complexity. "The results indicate that a degree of complexity represented by

six to eight dots is optimal for identification under these conditions. Ease of identification is

clearly shown to be associated with patterns having dots arranged either symmetrically or in

linear arrays." (PsycINFO Database Record (c) 2002 APA, all rights reserved)



French, R. S. (1954). “Pattern recognition in the presence of visual noise.” Journal of Experimental

Psychology 47(1): 27-31.



Fricke, T. and J. Siderov (1997). “Non-stereoscopic cues in the Random-Dot E stereotest: Results for

adult observers.” Ophthalmic and Physiological Optics 17(2): 122-127.

The purpose of this study was to investigate performance on the Random-Dot E (RDE)

stereotest under binocular and monocular non-stereoscopic viewing conditions. Sixteen adult

observers with normal vision were tested with the RDE stereotest. Four new RDE tests were

shown to each observer in varying combinations of monocular viewing, binocular but non-

stereoscopic viewing, and normal binocular viewing conditions. The test conditions were

masked (where possible) and were presented in pseudo-random order. Control experiments

were also conducted using the Frisby stereotest. Fifteen of the sixteen observers could discern

some differences between the plates monocularly and therefore satisfied the passing criterion

of the RDE test. Under these conditions, no observers could discern the stereoscopic E figure

nor did any observer report a sensation of depth. No observer satisfied the passing criterion of

the Frisby test monocularly. We conclude that caution should be used when interpreting

results from the RDE stereotest, since adult observers could discern some differences between

the test plates monocularly. (C) 1997 The College of Optometrists.



Frisby, J. P. (1975). “Random-dot stereograms for clinical assessment of stereopsis in children.”

Developmental Medicine and Child Neurology 17(6): 802-806.

Discusses random-dot stereograms, which are being used successfully with chidren, both as a

better method of screening for amblyopia and amblyopia-related disorders than has hitherto

been available, and to answer questions about the nature of the stereopsis-deficit in various

categories of squints. These promising new developments suggest that random-dot

stereograms will prove to be as useful for examining children as they already are for

examining adults. (French, German, & Spanish summaries) (PsycINFO Database Record (c)

2002 APA, all rights reserved) Record 836 of 887 in PsycINFO 1967-1977



Frisby, J. P. and J. L. Clatworthy (1975). “Learning to see complex random-dot stereograms.”

Perception 4(2): 173-178.

Many observers of complex random-dot stereograms find that the depth effect takes several

seconds, or even minutes, to develop. B. Julesz (1971) noted that giving a priori information to

such Os about the nature of the hidden cyclopean object appears to facilitate their stereopsis.

The present experiment investigated this possible facilitation. 103 naive undergraduates were

shown a complex stereogram following various kinds of preliminary assistance, ranging from

simply telling them about the amount of depth they could expect to see to showing them a full-

scale model of the cyclopean object. Surprisingly, no benefit from such assistance could be

demonstrated. All observers improved their stereopsis perception times with repeated

presentations of the stereogram, showing that they could, in principle, benefit from assistance.

A follow-up study 3 wks later revealed that a substantial part of this improvement was

maintained, indicating that the perceptual learning involved can last for a considerable period

of time. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 843 of 887 in

PsycINFO 1967-1977



Frisby, J. P. and J. E. Mayhew (1978). “Contrast sensitivity function for stereopsis.” Perception 7(4):

423-429.

Contrast thresholds for stereopsis from narrow-band filtered random-dot stereograms were

compared with contrast thresholds for simple detection of similar narrow-band noise. Using

the authors as observers, the study found that the contrast sensitivity function for stereopsis is

similar in shape to that for detection, suggesting that as far as contrast requirements are

concerned the mechanisms of global stereopsis do not show a bias in sensitivity to any

particular spatial frequency but instead require a constant level of suprathreshold contrast

regardless of spatial frequency. (9 ref) (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 795 of 887 in PsycINFO 1978-1984



Frisby, J. P. and J. E. Mayhew (1979). “Depth inversion in random-dot stereograms.” Perception 8(4):

397-399.

Contends that depth inversion is possible for a random-dot stereogram. The conditions under

which the inversion can be obtained are described, and evidence is presented in support of an

explanatory hypothesis. (3 ref) (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 785 of 887 in PsycINFO 1978-1984



Frisch, H. L. and B. Julesz (1966). “Figure-Ground Perception and Random Geometry.” Perception and

Psychophysics 1(11): 389-398.

CONSTRUCTS OF RANDOM GEOMETRY WERE APPLIED TO THE PROBLEM OF

FIGURE-GROUND PERCEPTION. RANDOM-DOT IMAGES OF BLACK AND WHITE

DOTS WITH VARIOUS AREA FRACTIONS AND TESSELATIONS (SQUARE AND

TRIANGULAR LATTICES) WERE USED AS STIMULI. THE CONSTRUCTS OF

RANDOM GEOMETRY ARE CORRELATION FUNCTIONS OF N-TH ORDER AND

SOME FUNCTIONALS DEFINED ON THEM. THE ONLY PARAMETER WHICH IS

INDEPENDENT OF THE TESSELATION USED IS THE 1ST-ORDER CORRELATION

WHICH IS THE AREA FRACTION. IT WAS 1ST CONJECTURED AND THEN

EXPERIMENTALLY VERIFIED THAT FIGURE-GROUND PERCEPTION IS NOT

AFFECTED BY THE VARIOUS TESSELATIONS USED. THUS, FIGURE-GROUND

PHENOMENA DEPEND ONLY ON THE AREA FRACTION OF THE WHITE AND

BLACK DOTS IN THE STIMULUS. THERE IS A PERCEPTUAL BIAS FOR WHITE, I.E.,

FIGURE-GROUND REVERSAL IS EASIEST AT 40% WHITE-BLACK AREA

FRACTION. IT WAS ALSO EXPERIMENTALLY SHOWN THAT SIZE-CONSTANCY

PREVAILS IN FIGURE-GROUND PERCEPTION, BUT BRIGHTNESS-CONSTANCY

DOES NOT. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 884 of

887 in PsycINFO 1872-1966



Fu, L. N. and R. G. Boothe (2001). “A psychophysical measurement and analysis of motion perception

in normal and binocularly deprived monkeys.” Investigative Ophthalmology & Visual Science

42(11): 2547-2553.

PURPOSE. To measure psychophysically the thresholds for motion detection in the nasal and

temporal directions under monocular viewing conditions in monkeys reared under conditions

of daily alternating monocular occlusion (AMO). The hypothesis was that motion perception

would be asymmetric with more sensitivity for motion in the nasal direction.METHODS.

Three monkeys subjected to AMO (AMO monkeys) and three normal monkeys were studied.

All were trained with operant conditioning techniques to discriminate coherent from random

motion in a random dot display. The percentage of dots in the display that moved either left or

right was varied. Thresholds for motion detection of nasally directed and temporally directed

stimuli were measured to determine whether the motion perception of AMO monkeys was

asymmetric, as predicted.RESULTs. A two-factor analysis of variance revealed a statistically

significant difference between treatment groups (normal versus AMO) and directions (nasal

versus temporal) and a significant interaction. The interaction was due to a significant

difference between nasal and temporal directions for the AMO group, but no significant

difference for the normal group. Planned comparisons were performed based on each animal's

best eye (eye most sensitive to nasal motion) and worst eye (eye least sensitive to temporal

motion). No significant differences were found between the two groups in the best eyes'

responses to the nasal direction, but the worst eyes' responses in the temporal direction were

significantly poorer in the AMO group. A neural model that can account for these findings is

based on a Hebbian teacher located in the nucleus of the optic tract that strengthens

connections of a subpopulation of directionally selective cortical neurons.CONCLUSIONS.

AMO rearing results in asymmetric motion perception. Thresholds for detecting nasally

directed motion are normal, whereas thresholds for detecting temporally directed motion are

deficient. These results demonstrate that motion-processing mechanisms in primates exhibit

experience-dependent developmental neural plasticity. The locus of the neural plasticity could

be a subpopulation of directionally selective neurons in the striate cortex (V1).



Fu, Y. X., Q. A. Xiao, et al. (1998). “Stimulus features eliciting visual responses from neurons in the

nucleus lentiformis mesencephali in pigeons.” Visual Neuroscience 15(6): 1079-1087.

The purpose of the present study was to find out what particular stimulus features, in addition

to the direction and velocity of motion, specifically activate neurons in the nucleus lentiformis

mesencephali (nLM) in pigeons. Visual responses of 60 nLM cells to a variety of computer-

generated stimuli were extracellularly recorded and quantitatively analyzed. Ten recording

sites were histologically verified to be localized within nLM with cobalt sulfide markings. It

was shown that the pigeon nLM cells were specifically sensitive to the leading edge moving at

the optimal velocity in the preferred direction through their excitatory receptive fields (ERFs).

Generally speaking, nLM cells preferred black edges to white ones. However, this preference

cannot be explained by OFF-responses to a light spot. The edge sharpness was also an

essential factor influencing the responsive strength, with blurred edges producing little or no

visual responses at all. These neurons vigorously responded to black edge orientated

perpendicular to, and moved in, the preferred direction; the magnitude of visual responses was

reduced with changing orientation. The spatial summation occurred in all neurons tested,

characterized by the finding that neuronal firings increased as the leading edge was lengthened

until saturation was reached. On the other hand, it appeared that nLM neurons could not detect

any differences in the shape and area of stimuli with an identical edge. These data suggested

that feature extraction characteristics of nLM neurons may be specialized for detecting

optokinetic stimuli, but not for realizing pattern recognition. This seems to be at least one of

the reasons why large-field gratings or random-dot patterns have been used to study visual

responses of accessory optic neurons and optokinetic nystagmus, because many high-contrast

edges in these stimuli can activate a neuron to periodically discharge, or groups of neurons to

simultaneously fire to elicit optokinetic reflex.



Fujikado, T., J. Hosohata, et al. (1998). “Use of dynamic and colored stereogram to measure stereopsis

in strabismic patients.” Japanese Journal of Ophthalmology 42(2): 101-107.

The effectiveness of movement or color has not been well studied in assessing stereopsis in

patients with strabismus. We developed a new stereotest equipped with both a monochromatic

dynamic random dot stereogram (DRDS) and a static-colored stereogram (SCS) and examined

the stereopsis of patients with strabismus. Three-dimensional (3D) images were displayed on a

liquid crystal display equipped with a parallax barrier system, allowing 3D images to be seen

independently by each eye without glasses. A DRDS with maximum disparity of 3200

seconds of are was displayed having front-rear movement. An SCS displaying cartoon

characters with disparities of 400 seconds of are was also tested and compared with the Titmus

stereotest. A total of 52 strabismic patients were tested. The DRDS showed a significantly

higher (P = 0.02) detection rate of stereopsis (39/52, 75%) as compared with the Titmus fly

test (28/52, 54%). The SCS did not show any difference in the stereopsis detection rate

(24/521, 46%) when compared with the Titmus animal test (20/52, 38%). Thus, the DRDS

was useful in detecting stereopsis in patients without stereopsis on the conventional Titmus fly

test, while the SCS did not show any difference when compared with the Titmus animal test.

The DRDS may examine a different aspect of stereopsis from the static stereopsis measured

by the Titmus stereotest or SCS. (C) 1998 Japanese Ophthalmological Society.

Fujikado, T., J. Hosohata, et al. (1996). “A clinical evaluation of stereopsis required to see 3-D

images.” Ergonomics 39(11): 1315-1320.

Some children with esotropia who have been diagnosed as 'stereoblind' on the basis of

conventional stereotests (which principally use static images with small disparity) may

nevertheless enjoy stereopsis for three-dimensional (3-D) animations that use dynamic images

with large disparity. The purpose of this study was to develop a new stereotest equipped with

dynamic random-dot stereogram (DRDS) which has larger disparity with movement and use it

with esotropic children to see if they can attain stereopsis for such images. Subjects were 17

esotropic children between 5 and 10 years old (mean age 6.8 years) who had failed to

demonstrate stereopsis with the Titmus fly test. Seven children had infantile esotropia and 10

had partially accommodative esotropia. The test images were DRDS that were presented on a

fluorescent screen (12 x 9 cm) viewed through a lenticular lens. The dots were displayed in

circle and triangle patterns that have counterphase front-rear movement with maximum

disparity of 800 s. Patients were placed with eyes at a distance of 60 cm from the screen and

were instructed to point out the pattern (circle or triangle) that was produced. The average

angle of strabismus was 7.7 Delta by alternating prism cover test (5 m). Seven patients passed

and 10 failed the DRDS test. There was no significant difference in the mean angle of

strabismus or the age of examination between the two groups; however, the age at onset of

strabismus was significantly higher in those who passed the DRDS test. These results suggest

that the DRDS test is useful in evaluating the potential stereopsis in children with esotropia

who do not pass conventional stereotests.



Fushiki, H., S. Takata, et al. (1999). “Circular vection in patients with age-related macular

degeneration.” Journal of Vestibular Research-Equilibrium & Orientation 9(4): 287-291.

We have used optokinetic stimulation in patients with unilateral age-related macular

degeneration (AMD) and central scotoma to investigate the possible contribution of the central

visual field to circular vection (CV). Six patients aged 42-73 years with unilateral AMD and

an aged-matched control group of nine elderly adults aged 47-75 years were examined.

Monocular visual field defects were verified with the Goldmann perimeter by kinetic

perimetry. The device used to induce CV was a random dot pattern projected onto a

hemispherical dome with a radius of 75 cm. The pattern was rotated horizontally at a constant

acceleration of 1 deg/s(2). Monocular stimuli were randomly repeated two to three times in

both temporal-nasal (T-N) and nasal-temporal (N-T) directions. The latency of onset of CV

was measured for each stimulus presentation. In the age-matched control group the CV

latencies varied from 4.2 to 72.0 s. In each case, however, the CV latencies were stable. No

significant differences in CV latencies were found between right and left eyes in both stimulus

directions (p > 0.05). In patients with AMD, no statistically significant difference in CV

latency was found between the affected and unaffected eyes (p > 0.05). Marked central visual

field loss in AMD does not significantly impair peripherally induced CV. Our results are

compatible with the hypothesis that the peripheral retina dominates CV.



Fushiki, H., S. Takata, et al. (2000). “Directional preponderance in pitch circular vection.” Journal of

Vestibular Research: Equilibrium and Orientation 10(2): 93-98.

Used optokinetic stimulation (OKS) in 18 healthy adults (aged 18-30 yrs) to investigate

vertical self-motion perception. To induce self-rotation, either a stripe pattern or a random dot

pattern was projected onto the inner wall of a hemispherical dome with a diameter of 150 cm.

The pattern was rotated either about the S's vertical axis (yaw) or about the S's interaural axis

(pitch) for 80 sec at a constant acceleration of 1 deg/sec-sup-2. Stimuli were randomly

repeated 3 to 4 times in each direction. The latency of onset as well as the perceived intensity

of circular vection (CV) was measured for each stimulus presentation. CV latencies for

upward rotational stimulation were significantly longer than those for downward rotational

stimulation under both types of stimulus conditions. There was no significant difference in CV

latency between rightward and leftward rotational stimulation. For most Ss, the magnitudes of

the perceived CV for rightward rotational stimulation were equal to those for leftward

rotational stimulation, whereas the magnitudes of the perceived CV for vertical stimulation

showed large intersubject variability. These results provide additional evidence that

fundamental differences exist between different types of self-motion. (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 143 of 887 in PsycINFO 2000

Fushiki, H., S. Takata, et al. (2000). “Influence of fixation on circular vection.” Journal of Vestibular

Research-Equilibrium & Orientation 10(3): 151-155.

The contribution of fixation to latency of circular vection (CV) was examined in twenty-five

normal adults aged 18-30 years. For induction of self-motion a random dot pattern was

projected onto a hemispherical dome. The pattern was rotated either about the subject's

vertical axis or about their interaural axis at a constant acceleration of 1 deg/s(2). For the

group tested, the perceived CV latencies were significantly shorter with fixation than without

fixation in both horizontal and vertical CV. The effect of fixation was pronounced in subjects

with longer latencies. The mean CV latencies for two different fixation points between the

subject's eyes and the moving pattern did not differ significantly. Our results suggest that the

potential influence of fixation must be carefully controlled in studies of visually induced self-

motion. Possible explanations for the effect of fixation on the generation of CV will also be

discussed.



Fushiki, H., S. Takata, et al. (2000). “Directional preponderance in pitch circular vection.” Journal of

Vestibular Research-Equilibrium & Orientation 10(2): 93-98.

We used optokinetic stimulation (OKS) in eighteen normal adults aged 18-30 years to

investigate vertical self-motion perception. In order to induce self-rotation, either a stripe

pattern or a random dot pattern was projected onto the inner wall of a hemispherical dome

with a diameter of 150 cm. The pattern was rotated either about the subject's vertical axis

(yaw) or about the subject's interaural axis (pitch) for 80 s at a constant acceleration of 1

deg/s(2). Stimuli were randomly repeated three to four times in each direction. The latency of

onset as well as the perceived intensity of circular vection (CV) was measured for each

stimulus presentation. CV latencies for upward rotational stimulation were significantly longer

than those for downward rotational stimulation under both types of stimulus conditions. There

was no significant difference in CV latency between rightward and leftward rotational

stimulation. For most subjects, the magnitudes of the perceived CV for rightward rotational

stimulation were equal to those for leftward rotational stimulation, whereas the magnitudes of

the perceived CV for vertical stimulation showed large intersubject variability. These results

provide additional evidence that fundamental differences exist between different types of self-

motion. Possible explanations for the directional asymmetry in vertical perception of self-

motion will also be discussed.



Ganis, G., C. Casco, et al. (1993). “Perceived Rigidity and Nonrigidity in the Kinetic Depth Effect.”

Perception 22(1): 23-34.

Stroboscopic simulations of three-dimensional rotating rigid structures can be perceived as

highly nonrigid. To investigate this nonrigidity effect a sequence of either three (experiment 2

and 3) or thirty six frames (experiment 4) was used, each consisting of a set of dots with

location on the horizontal axis corresponding to the parallel projection of a nominally defined

helix. Observers were asked to judge the angle of rotation of eighty helices defined by the

factorial combination of eight phase (phi) values (ie difference between the sinusoidal path of

one dot and its neighbours) and ten different angular displacement values (alpha).When in

each static frame the dots can be organized into curved dotted line (small values of phi), the

perceived 3-D helices are highly nonrigid. But when shape information is not available in each

static frame (high values of phi), the helices are perceived as rigid and rotation judgement is

possible providing that alpha V2, V1 --> MT, and V1 --> V2 --

> MT exist for static form and motion form processing among the areas V1, V2, and MT of

visual cortex. The theory suggests that the static form system (Static BCS) generates emergent

boundary segmentations whose outputs are insensitive to direction-of-contrast and to

direction-of-motion, whereas the motion form system (Motion BCS) generates emergent

boundary segmentations whose outputs are insensitive to direction-of-contrast but sensitive to

direction-of-motion. The theory is used to explain classical and recent data about short-range

and long-range apparent motion percepts that have not yet been explained by alternative

models. These data include beta motion, split motion, gamma motion and reverse-contrast

gamma motion, delta motion, and visual inertia. Also included are the transition from group

motion to element motion in response to a Ternus display as the interstimulus interval (ISI)

decreases; group motion in response to a reverse-contrast Ternus display even at short ISIs;

speed-up of motion velocity as interflash distance increases or flash duration decreases;

dependence of the transition from element motion to group motion on stimulus duration and

size, various classical dependencies between flash duration, spatial separation, ISI, and motion

threshold known as Korte's laws; dependence of motion strength on stimulus orientation and

spatial frequency; short-range and long-range form-color interactions; and binocular

interactions of flashes to different eyes.



Grossman, E. D. and R. Blake (1999). “Perception of coherent motion, biological motion and form-

from-motion under dim-light conditions.” Vision Research 39(22): 3721-3727.

Three experiments investigated several aspects of motion perception at high and low

luminance levels. Detection of weak coherent motion in random dot cinematograms was

unaffected by light level over a range of dot speeds. The ability to judge form from motion

was, however, impaired at low light levels, as was the ability to discriminate normal from

phase-scrambled biological motion sequences. The difficulty distinguishing differential

motions may be explained by increased spatial pooling at low light levels. (C) 1999 Elsevier

Science Ltd. All rights reserved.



Grove, P. M., B. Gillam, et al. (2002). “Content and context of monocular regions determine perceived

depth in random dot, unpaired background and phantom stereograms.” Vision Research

42(15): 1859-1870.

Perceived depth was measured for three-types of stereograms with the colour/texture of half-

occluded (monocular) regions either similar to or dissimilar to that of binocular regions or

background. In a two-panel random dot stereogram the monocular region was filled with

texture either similar or different to the far panel or left blank. In unpaired background

stereograms the monocular region either matched the background or was different in colour or

texture and in phantom stereograms the monocular region matched the partially occluded

object or was a different colour or texture. In all three cases depth was considerably impaired

when the monocular texture did not match either the background or the more distant surface.

The content and context of monocular regions as well as their position are important in

determining their role as occlusion cues and thus in three-dimensional layout. We compare

coincidence and accidental view accounts of these effects. (C) 2002 Elsevier Science Ltd. All

rights reserved.



Grove, P. M., B. J. Gillam, et al. (2001). “Continuation of monocular region with background as an

ecological feature determining degree of depth in random dot stereograms and in unpaired

"black box" stereograms.” Investigative Ophthalmology & Visual Science 42(4): S938-S938.



Grove, P. M. and H. Ono (1999). “Ecologically invalid monocular texture leads to longer perceptual

latencies in random-dot stereograms.” Perception 28(5): 627-639.

Two experiments were conducted to explore Gillam and Borsting's (1988, Perception 17 603-

608) report that uncorrelated monocular texture facilitates stereopsis by shortening the latency

to see depth in random-dot stereograms. Experiment 1 used stereograms similar, in pattern but

not disparity, to Gillam and Borsting's with monocular texture present or absent. A third

condition, where monocular texture was dissimilar to the binocular panels and background,

was also used. We were unable to generalize the findings of Gillam and Borsting for a depth

step of 6 min of are to a larger depth step of 24 min of are. That is, we observed no significant

difference in latencies between the conditions with monocular texture absent and present at a

disparity of 24 min of are. We found latencies to be significantly longer in the monocular-

texture-different condition than the monocular-texture-absent condition, however. We account

for this, ad hoc, by arguing that the monocular-texture-different stereogram depicts a rare or

'accidental' visual scenario. This account was supported by the results of experiment 2 which

showed that stereograms depicting accidental views yielded longer latencies than those

depicting generic views. We conclude that the ecological validity of monocular texture must

also be considered when assessing the effects of monocular texture on stereopsis.



Gruber, J., P. Dickey, et al. (1985). “Comparison of a Modified (2-Item) Frisby with the Standard

Frisby and Random-Dot E Stereotests When Used with Preschool-Children.” American

Journal of Optometry and Physiological Optics 62(5): 349-351.



Grzywacz, N. M., S. N. J. Watamaniuk, et al. (1995). “Temporal Coherence Theory for the Detection

and Measurement of Visual-Motion.” Vision Research 35(22): 3183-3203.

A recent challenge to the completeness of some influential models of local-motion detection

has come from experiments in which subjects had to detect a single dot moving along a

trajectory amidst noise dots undergoing Brownian motion. We propose and test a new theory

of the detection and measurement of visual motion, which can account for these signal-in-

Brownian-noise experiments. The theory postulates that the signals from local-motion

detectors are made coherent in space and time by a special purpose network, and that this

coherence boosts signals of features moving along non-random trajectories over time. Two

experiments were performed to estimate parameters and test the theory. These experiments

showed that detection is impaired with increasing eccentricity, an effect that varies inversely

with step size. They also showed that detection improves over durations extending to at least

600 msec. An implementation of the theory accounts for these psychophysical detection

measurements.

Gu, Y., Y. Wang, et al. (2002). “Visual responses of neurons in the nucleus of the basal optic root to

stationary stimuli in pigeons.” Journal of Neuroscience Research 67(5): 698-704.

The nucleus of the basal optic root of the accessory optic system in pigeons is involved in

generating optokinetic nystagmus, which stabilizes object images on the retina by

compensatory eye movements. Previous studies have indicated that basal optic neurons are

selective for the direction and velocity of motion. The present study shows that these

optokinetic cells also respond to stationary stimuli and thereby could be categorized into three

groups. The first group of cells (69.1%) responds to stationary gratings orthogonal to the

preferred direction but not to gratings parallel to the preferred direction. They do not respond

to stationary random-dot patterns without any orientational cues. The second group of cells

(7.4%) almost equally discharges a series of bursts in response to stationary gratings with any

orientations and to random-dot patterns as well. The third group of cells (23.5%) is responsive

to motion but not to stationary gratings and random-dot patterns. The receptive field of basal

optic cells is composed of an excitatory field and an inhibitory field, both of which overlap or

occupy different regions in the visual field. The aforementioned properties may be attributed

to the excitatory receptive field, whereas the inhibitory receptive field is functional when

visual stimuli are moving in the direction opposite to the preferred direction of basal optic

cells. The functional significance of visual responses of optokinetic neurons to stationary

patterns is discussed. (C) 2002 Wiley-Liss, Inc.



Guillemot, J. P., M. C. Paradis, et al. (1993). “Binocular Interaction and Disparity Coding in Area 19 of

Visual-Cortex in Normal and Split-Chiasm Cats.” Experimental Brain Research 94(3): 405-

417.

Binocular disparity, resulting from the projection of a three-dimensional object on the two

spatially separated retinae, constitutes one of the principal cues for stereoscopic perception.

The binocularity of cells in one hemisphere stems from two sources: (1) the ganglion cells in

the homonymous temporal and nasal hemiretinae and (2) the contralateral hemisphere via the

corpus callosum (CC). The objectives of this study were, on one hand, to determine whether

disparity-sensitive cells are present in a ''higher order'' area, namely area 19 of the visual

cortex, of the cat and, on the other hand, to ascertain whether the CC contributes to the

formation of these cells. As in areas 17-18, two types of disparity-sensitive neurons were

found: one type, showing maximal interactive effects around zero disparity, responded with

strong excitation or inhibition when the stimuli presented independently to the two eyes were

in register. These neurons are presumed to signal stimuli situated about the fixation plane. The

other type, also made up of two subtypes of opposed valencies, gave maximum responses at

one set of disparities and inhibitory responses to the other set. These are presumed to signal

stimuli situated in front of or behind the fixation plane. Unlike areas 17-18, however,

disparity-sensitive cells in area 19 of the normal cat were less finely tuned and their proportion

was lower. In the split-chiasm animal, very few cells were sensitive to disparity. These results,

when coupled with behavioral data obtained with destriate animals, indicate that (1) area 19 is

probably less involved in the analysis of disparity information than area 17, (2) the disparity-

sensitive neurons that arc sensitive to disparity are not involved in the resolution of very fine

three-dimensional spatial detail, and (3) the CC only determines a limited number of these

cells in the absence of normal binocular input.



Guo, K. and C. Li (1995). “A quantitative study of random-dot induced stereo vision under luminance

contrast and color contrast.” Acta Psychologica Sinica 27(2): 167-173.

Investigated the depth perception in random-dot stereograms (RDSs) under heteroluminance

(H) without chromaticity contrast and equiluminance with chromaticity contrast (CC). Three

male Ss (aged 21-25 yrs) in China were tested on the computer. Exp 1 tested the effects of

contrast (in the range of 10%-99%) on the disparity threshold (DT); Exp 2 tested DT in H

(60%) and CC (background 10 cd/m-sub-2); Exp 3 tested DT in distinguishing RDSs with CC

(red/green for left visual field and yellow/blue and green/purple for right visual field) under

equiluminance; Exp 4 tested DT in distinguishing RDSs with black/white RDSs in the left

visual field and red/green RDSs in the right visual field under equiluminance. The results were

that RDSs were found to induce depth equally well in both display modes; that there were no

significant differences of DT for perceiving depth in both display modes; and that under the

condition where one eye was stimulated with CC RDSs and another with H RDSs, Ss could

perceive depth only when the contrast of CC RDS was substantially above equiluminance. It is

suggested that stereoscopic depth is mediated by both the magnocellular and parvocellular

(blob and interblob) systems. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 355 of 887 in PsycINFO 1993-1995



Gurney, K. N. and M. J. Wright (1996). “A model for the spatial integration and differentiation of

velocity signals.” Vision Research 36(18): 2939-2955.

We present a model of optic flow processing which is able to reconcile the integrative,

cooperative phenomena of motion capture and coherence with the differentiation of velocity

signals in motion segmentation and transparency, The model uses a Markov random field to

compute the behaviour of coextensive topographic neural maps of retinotopy and velocity. We

have used the model to simulate the psychophysics of motion coherence, motion capture and

transparency. Further, it exhibits motion segmentation without extra postulates. The model is

robust and able to display all types of motion percept with the same parameter set. Copyright

(C) 1996 Elsevier Science Ltd.



Gurnsey, R. and R. A. Browse (1987). “Micropattern properties and presentation conditions

influencing visual texture discrimination.” Perception and Psychophysics 41(3): 239-252.

Tested, in 4 experiments involving 36 university students, whether line crossings and

terminators elicit effortless discrimination independently of configurational differences as

predicted by texton theory. Ss were required to detect a disparate textured region embedded in

an unpredictable quandrant of a textural display. The textural displays were presented for brief

durations (67-267 msec) and followed by a random dot mask. When configuration was

controlled, micropatterns differing in terminators and line crossings elicited relatively poor

discrimination. Ease of discrimination was largely associated with differences in micropattern

size. For certain texture pairs, ease of discrimination depended on which member of the pair

formed the embedded region and which formed the background, which also related to size.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 633 of 887 in

PsycINFO 1985-1987



Gurnsey, R., A. M. Herbert, et al. (1998). “Bilateral symmetry embedded in noise is detected

accurately only at fixation.” Vision Research 38(23): 3795-3803.

Bilateral or mirror symmetry is a ubiquitous feature of biological forms that the visual system

could exploit for segmenting an object from a cluttered background. If this is so, the visual

system may be prepared to detect symmetry at all retinal locations in parallel. Indeed, a

biologically plausible model that responds optimally at axes of symmetry is quite easy to

construct. Our data show, however, that if such a mechanism exists, it works with high

efficiency only at the fovea. The detection of vertical bilateral symmetry embedded in random

noise is very poor unless the axis of symmetry is very close to the point of fixation. This leads

to the conclusion that symmetry does not play an important role in image segmentation and

that it is important to the visual system only after it is fixated. (C) 1998 Elsevier Science Ltd.

All rights reserved.



Habak, C., C. Casanova, et al. (2002). “Central and peripheral interactions in the perception of optic

flow.” Vision Research 42(26): 2843-2852.

Evaluated the effects of central and peripheral stimulation on the perception of optic flow over

large spatial extents. Coherence thresholds were measured for random-dot kinematograms

simulating observer translation and radial motion. Experiments 1 and 3a measured sensitivity

to a range of speeds for a circular central region, for several annular regions of increasing

eccentricity, and for a full-field stimulus (80 deg. diameter). Results suggest that the spatial

extent over which signals are integrated may vary in order to maximize the information

available for perceptual representations. Experiments 2 and 3b evaluated central and

peripheral interactions in a direction discrimination task, by comparing the effects of different

signal strengths and directions in 1 of the 2 regions. The presence of noise dots in either center

or periphery led to a performance decrease from baseline measures. A similar decrease was

observed when dots in the 2 regions moved in opposite directions. These findings suggest that

central and peripheral inputs are not separable in the integration of optic flow, that they

contribute equally to the percept under normal conditions, and that peripheral stimulation

seems important under ecologically relevant conditions such as poor visibility. (PsycINFO

Database Record (c) 2003 APA, all rights reserved) Record 34 of 887 in PsycINFO 2003/01-

2003/06

Hadani, I. (1984). “Visual Comet Tails in Unidirectional Apparent Motion of Random-Dot Patterns.”

Perception 13(1): A40-A40.



Hadani, I. (1991). “Corneal Lens Goggles and Visual Space-Perception.” Applied Optics 30(28): 4136-

4147.

Night vision goggles are head-mounted, unity-power systems designed to allow the human

operator to see and operate at night. Field experience and experimental studies have revealed

many drawbacks in conventional designs that impair performance. One major drawback is the

poor space perception provided by the goggles. The Hadani et al. [J. Opt. Soc. Am. 70, 60-65

(1980)] model for space perception attributes this drawback to the fact that the conventional

designs shift the observer's effective center of perspective approximately 15 cm ahead and

also predicts the resulting impairments. An innovative redesign is presented in this paper-the

corneal lens goggles (CLG)-which brings the effective center of perspective of the goggles to

coincide with the center of perspective of the eyes, thus annulling the optical length of the

device. Qualitative and quantitative laboratory studies have compared the performance of the

CLG and conventional goggles (type AN/PVS-5). These studies have revealed better visual

and visual-motor performance with the CLG. The implications to optical design of the Hadani

et al. theory and the CLG concept are discussed.



Hadani, I., M. Gur, et al. (1980). “Hyperacuity in the Detection of Differential Motion between 2

Random Dot Patterns.” Physics in Medicine and Biology 25(5): 1002-1002.



Hadani, I., M. Gur, et al. (1981). “Detection of Differential Displacements of Random Dot Patterns at

Different Dot Densities.” Vision Research 21(7): 1193-1195.



Hadani, I., M. Gur, et al. (1980). “Hyperacuity in the Detection of Absolute and Differential

Displacements of Random Dot Patterns.” Vision Research 20(11): 947-951.



Hadani, I. and N. Vardi (1987). “Stereopsis Impairment in Apparently Moving Random Dot Patterns.”

Perception & Psychophysics 42(2): 158-165.



Hahn, W., H. Scheiblechner, et al. (1990). “Ein Experiment zur Theorie der visuellen

Bewegungswahrnehmung. / An experiment on theories concerning visual perception of

movement.” Zeitschrift fuer Experimentelle und Angewandte Psychologie 37(3): 378-398.

Tested 2 theoretical models of the visual perception of movement: (1) the correlation model,

and (2) the gradient model. Human subjects: Seven normal male and female West German

adults (aged 26-38 yrs). Ss were presented with random-dot kinematograms with a shifted

square, and the maximum shift meeting the 80% threshold for detection of correct direction

was determined. Results were analyzed in relation to predictions based on the 2 models.

(English abstract) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 536

of 887 in PsycINFO 1990-1992



Hallett, M. B. and E. J. Pettit (1997). “The use of single image random dot stereograms for presenting

3D microscopic confocal images.” Journal of Microscopy-Oxford 186: 275-278.

Presenting 3D images produced by confocal optical slicing techniques in a static and easily

publishable form can be difficult. Here, we demonstrate the presentation of the data as a single

image random dot stereogram (SIRD), which can be viewed as a 3D object by 'defocusing' the

eyes. The production of the SIRD employs three steps: (i) acquisition of the optical slices

using confocal techniques, (ii) allocation of a suitable grey level to the object in each slice to

provide depth-encoding information for the final image and (iii) calculation of the SIRD from

the composite depth-encoded image. The technique is demonstrated with a limited number of

optical slices through an acridine-orange-stained neutrophil (diameter = 10 mu m), in order to

show the relative positions of the nuclear lobes in the cell.



Halpern, D. L. (1991). “Stereopsis from Motion-Defined Contours.” Vision Research 31(9): 1611-

1617.

Random-dot stereograms demonstrate that monocularly visible contours are not necessary for

stereopsis, although in the absence of point-for-point correspondence, they are sufficient for

stereoscopic combination. The quality of stereopsis from interocularly uncorrelated motion-

defined forms was examined here. Results indicate that perceived magnitude of depth is not

veridical, and that more depth is seen for crossed than uncrossed disparities. The difficulty in

perceiving "behind" depth is due to a monocular depth cue which conflicts with binocular

disparity in specifying depth only in the absence of interocular correlation. The overall

reduction in depth is not the result of binocular rivalry from the lack of interocular correlation,

and so appears to be a function of the type of feature being matched.



Halpern, D. L., H. R. Wilson, et al. (1996). “Stereopsis from interocular spatial frequency differences is

not robust.” Vision Research 36(15): 2263-2270.

Based on data obtained using one-dimensional noise patterns, Tyler & Sutter (1979). (Vision

Research, 19, 859-865) concluded that stereoscopic tilt can result from an interocular spatial

frequency difference in the absence of consistent horizontal disparity, We tested stereopsis

using two-dimensional random-dot patterns that were bandpass filtered to contain 1.0 octave

bands of spatial frequency with means that differed between the two eyes. With vertical, one-

dimensional stimuli we replicated the results of Tyler and Sutter. However, stereoscopic tilt

was not perceived based on spatial frequency differences alone when the monocular images

contained as little as a +.-14 deg range of orientation variation. In addition, model simulations

demonstrate that the modest stereoscopic performance produced by interocular spatial

frequency differences in one-dimensional noise patterns are predicted by random disparity

correlations at the pattern edges, These observations lead to the conclusion that stereopsis

from frequency differences in the absence of pointwise disparity correlations does not reflect a

special processing capability of human vision but is an artifact associated with one-

dimensional stimuli, As such, it plays no role in stereoscopic analysis of the natural

environment. Copyright (C) 1996 Published by Elsevier Science Ltd.



Hammond, P. (1991). “On the Response of Simple and Complex Cells to Random Dot Patterns - a

Reply.” Vision Research 31(1): 47-50.



Hammond, R. S. and P. P. Schmidt (1986). “A Random Dot-E Stereogram for the Vision Screening of

Children.” Archives of Ophthalmology 104(1): 54-60.



Hamori, E., R. D. Broad, et al. (1982). “Study of unaided cross-eyed stereopsis.” Perception 11(3):

297-304.

Investigated the learning of the skill of unaided cross-eyed stereopsis in 2 experiments with 29

18-67 yr olds. Both pictorial and random-dot stereograms were used; small stereograms were

viewed at normal reading distance, and large projected stereograms were viewed in an

auditorium. Results indicate that this direct stereoscopic technique was learned within a few

minutes by almost everyone in the population represented by the test group. The calculated

eye-convergence angles for various conditions of cross-eyed stereoscopic viewing indicated

that little eye discomfort was caused by this factor when the stereograms were located at a

sufficient distance from the viewers. Ss' comments support this conclusion. The unexpected

prevalence of the aptitude for this skill should have practical application in the unaided 3-

dimensional visualization of computer-generated stereograms. (12 ref) (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 731 of 887 in PsycINFO 1978-1984



Hanada, M. and Y. Ejima (2000). “Heading judgement from second-order motion.” Vision Research

40(24): 3319-3331.

We examined human heading judgement from second-order motion which was generated by

random-dots with the contrast polarity determined randomly on each frame. It was found that

human observers can judge heading fairly accurately from second-order motion when pure

translation is simulated or when self-motion toward a ground plane with gaze rotation is

simulated but they cannot when self-motion toward cloud-like random dots with gaze

rotations is simulated. It is suggested that the human visual system cannot decompose the flow

fields into rotational and translational components by using second-order motion information

alone, but it can do in some ways from the flow field of the ground plane. (C) 2000 Elsevier

Science Ltd. All rights reserved.



Hansen, P. C., J. F. Stein, et al. (2001). “Are dyslexics' visual deficits limited to measures of dorsal

stream function?” Neuroreport 12(7): 1527-1530.

We tested the hypothesis that the differences in performance between developmental dyslexics

and controls on visual tasks are specific for the detection of dynamic stimuli. We found that

dyslexics were less sensitive than controls to coherent motion in dynamic random dot

displays. However, their sensitivity to control measures of static visual form coherence was

not significantly different from that of controls. This dissociation of dyslexics' performance on

measure that are suggested to tap the sensitivity of different extrastriate visual areas provides

evidence for an impairment specific to the detection of dynamic properties of global stimuli,

perhaps resulting from selective deficits in dorsal stream functions. NeuroReport 12:1527-

1530 (C) 2001 Lippincott Williams & Wilkins.



Haring, G., A. Gronemeyer, et al. (1999). “Stereoacuity and aniseikonia after unilateral and bilateral

implantation of the Array refractive multifocal intraocular lens.” Journal of Cataract and

Refractive Surgery 25(8): 1151-1156.

Purpose: To evaluate stereoacuity and aniseikonia in eyes with unilateral and bilateral

implantation of the Allergan Array(R) refractive multifocal intraocular lens (MIOL).Setting:

Department of Ophthalmology, University Hospital, Kiel, Germany.Methods: This study

comprised 31 patients with a unilateral MIOL and a phakic fellow eye and 29 patients with

bilateral MIOLs. in all pseudophakic eyes, an Array MIOL had been implanted between 1991

and 1994 during a prospective clinical trial. In the present study, patients were re-examined.

Near and distance visual acuity were i tested; binocular functions were assessed using

Bagolini lenses, the Worth 4-dot test, the Lang random-dot test, and the Titmus fly chart.

Aniseikonia was evaluated using Aulhorn's phase-difference haploscope. Mean follow-up was

43 months in both groups.Results: After unilateral implantation 87.1% of patients and after

bilateral implantation 93.1% of patients correctly perceived the stereograms of the Lang

random-dot test. The mean subjective height of the measured Titmus fly was 4.2 cm after

unilateral and 4.3 cm after bilateral implantation. The stereoacuity tests revealed no

statistically significant differences between the groups. Distance and near aniseikonia were

significantly less after bilateral than after unilateral implantation.Conclusion: Despite the

simultaneous formation of multiple retinal images, the Array MIOL allowed good binocular

vision including random-dot stereopsis. Functional aniseikonia developed but did not interfere

with normal binocular vision. (C) 1999 ASCRS and ESCRS.



Harrad, R. A., S. P. McKee, et al. (1994). “Binocular rivalry disrupts stereopsis.” Perception 23(1): 15-

28.

Measured the amount of time required to shift from rivalry to stereo fusion. Stereoacuity

(STA) was measured after rivalry suppression of one half-image of a STA line target. After

the observer signaled that the single stereo half-image had been suppressed, the other half-

image was presented for a variable duration. STA thresholds were elevated for 150-200 msec.

Data from 3 observers show that an appropriately matched stereo pair can break rivalry

suppression more easily than can monocular changes in position. The duration needed to

detect a disparate feature in a random-dot stereogram was also measured after rivalry

suppression of one half-image of the stereogram. Ss were able to correctly identify the

location of the disparate feature when the other half-image was presented for a duration

ranging from 150-650 msec. Although stereopsis and fusion terminate rivalry, both are

initially disrupted for a few hundred milliseconds by rivalry suppression. (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 438 of 887 in PsycINFO 1993-1995



Harrad, R. A., S. P. McKee, et al. (1994). “Binocular-Rivalry Disrupts Stereopsis.” Perception 23(1):

15-28.

Does the shift from binocular rivalry to fusion or stereopsis take time? We measured

stereoacuity after rivalry suppression of one half-image of a stereoacuity line target. After the

observer signalled that the single stereo half-image had been suppressed, the other half-image

was presented for a variable duration. Stereoacuity thresholds were elevated for 150 - 200 ms.

A control experiment demonstrated that the threshold elevation was due to rivalry suppression

per se, rather than masking effects associated with the rivalry-inducing target. Monocular

Vernier thresholds, measured as the smallest identifiable abrupt shift in the upper line of an

aligned Vernier target that had previously been suppressed by rivalry, were elevated for a

much longer duration. This result shows that an appropriately matched stereo pair can break

rivalry suppression more easily than can monocular changes in position. With the aid of a

similar paradigm, we also measured the duration needed to detect a disparate feature in a

random-dot stereogram after rivalry suppression of one half-image of the stereogram.

Observers could correctly identify the location of the disparate feature (upper or lower visual

field) when the other half-image was presented for a duration ranging from 150 - 650 ms. In

the absence of the matching half-image, the first half-image was suppressed by the rival target

for a far longer duration (a few seconds). These findings show that although stereopsis and

fusion terminate rivalry, both are initially disrupted for a few hundred milliseconds by rivalry

suppression.



Harris, J. M., S. P. McKee, et al. (1997). “Fine-scale processing in human binocular stereopsis.”

Journal of the Optical Society of America a-Optics Image Science and Vision 14(8): 1673-

1683.

Many studies have demonstrated that the human visual system is sensitive to very small

differences in relative binocular disparity. It is not known over what monocular regions

information is spatially integrated to mediate performance in such tasks. In this study we

present psychophysical observations that define the smallest spatial scale involved in disparity

processing, and we indicate the nature of the computations performed by the units mediating

that disparity discrimination. We show that human observers can identify the sign of disparity

of a single target dot when it is embedded in a row of identical dots, with these noise dots

presented either in the fixation plane or with a proportion binocularly uncorrelated. In

conjunction with the psychophysical data, we explore how a class of simple correlator models

of stereopsis must be constrained in order to account for human performance for the same

fine-scale tasks. Such models can perform the task only when the correlation is carried out

over a very small region of the image, for a very small range of disparities; Our results

demonstrate that there is a fine-scale input to the stereo system, mediated by foveal

mechanisms that spatially integrate visual signals over a region as small as 4-6 arcmin in

diameter. (C) 1997 Optical Society of America.



Harris, J. M. and A. J. Parker (1992). “Efficiency of Stereopsis in Random-Dot Stereograms.” Journal

of the Optical Society of America a-Optics Image Science and Vision 9(1): 14-24.

The statistical efficiency of stereopsis was investigated by measurement of the discriminability

d' of a step edge in depth in a random-dot stereogram and its comparison with d' calculated for

an ideal observer model. Efficiencies of approximately 20% were found for stimuli with very

few ( 73 msec), When

they were uncorrelated, higher-order SM dominated even under zero ISI conditions, Subjects

reported that, when higher-order SM was seen, dots were attached to the surfaces of the

moving cyclopean figure (motion capture), Experiment 2 tested which factor caused the

domination of higher-order SM under uncorrelated conditions in Experiment 1, the larger

distance of dot jump or the varied directions of the dots' motion, The results show that, when

the distance of dot jump is large or when the directions of dots' motion are incoherent, higher-

order SM arises more frequently, When local first-order motion signals are weakened by

appropriate temporal and spatial conditions or by incoherent motion directions, higher-order

SM dominates and it captures the motion of dots, (C) 1997 Elsevier Science Ltd.



Ito, H. (1999). “Two processes in stereoscopic apparent motion.” Vision Research 39(16): 2739-2748.

This study investigated the human ability to discriminate the motion direction of sequentially

presented depth patterns produced by random-dot stereograms. The stereoscopic (cyclopean)

patterns used here consisted of 256 rectangle patches, each of which had an alternative depth

position (near or far). Two successive frames of correlated depth patterns made impressions of

lateral motion when the pattern position in the second frame shifted laterally. The density of

the patches that were near was varied. The D-max that was measured using the 2AFC method

was short when the density was high. The effect of depth reversing in the second frame was

also tested. Under low density conditions, the performance was still good against reversing 3-

D polarity. However, when the density was high, with depth reversal, motion in the reversed

direction was perceived. Reversed motion was observed more often when SOA was small and

when the density of near patches was near 1/2. Two strategies seem to exist in stereoscopic

motion detecting: a polarity-independent process which matches figures, ignoring their depth

polarity, and a polarity-dependent process which operates locally, ignoring 2-D shapes. The

latter suggests the existence of a passive process in stereoscopic motion. (C) 1999 Elsevier

Science Ltd. All rights reserved.



Ito, H. (2003). “The aperture problems in the Pulfrich effect.” Perception 32(3): 367-375.

The Pulfrich effect yields a perceived depth for horizontally moving objects but not for

vertically moving ones. In this study the Pulfrich effect was measured by translating oblique

lines seen through a circular window, which made motion direction ambiguous. Overlaying

random dots that moved horizontally, vertically, or diagonally controlled the perceptual

motion direction of the lines. In experiment 1, when the lines were seen to move horizontally,

the effect was strongest in spite of the same physical motion of the lines. Experiment 2 was

performed to test the above conditions again, excluding the Pulfrich effect of the dots on the

depth of the lines. The overlaid dots were presented to one eye only. The result showed that

the Pulfrich effect of the lines was persistently strong in spite of the perceptual changes in

motion direction. Experiment 3 also showed that the Pulfrich depth was independent of the

perceived horizontal speed in a plaid display. The Pulfrich effect was determined by

measuring the horizontal disparity component, independently of the perceived motion

direction. These results demonstrate that the aperture problems in motion and stereopsis in the

Pulfrich effect are solved independently.



Ito, H. (2003). “Effect of element size on stereoscopic apparent motion.” Perceptual and Motor Skills

96(3): 1187-1193.

Spatial displacement limits in stereoscopic (cyclopean) apparent motion were measured from

sequentially presented two-frame random-depth configurations. Each depth configuration was

defined by stereoscopically near or far elements of various sizes. The limits were compared

with those in luminance-defined apparent motion, The subject's task was 2-alternative forced-

choice of the perceived motion direction of the sequentially presented two-frame random-dot

stereograms. The spatial displacement limit below which correct motion perception arose with

stereoscopic configurations was larger in proportion to increases in size of elements. The

values were almost consistent with those measured by luminance-defined configurations with

the same element sizes. This result suggests that the strategy for discrimination of motion

direction of random configurations is similar in both stereoscopic and luminance-defined

apparent motion.



Ito, H. and C. Fujimoto (2003). “Compound self-motion perception induced by two kinds of optical

motion.” Perception & Psychophysics 65(6): 874-887.

Two kinds of flow patterns consisting of random dots were presented simultaneously to

subjects to investigate whether or not two kinds of vection occur simultaneously. One pattern

induces vertical linear self-translation, whereas the other induces self-rotation around a

vertical axis (when either pattern is presented alone). Three sets of conditions were tested. The

first condition was one in which random dots moved in a summed direction of both flow

vectors. In the second condition, both flow patterns were simply overlaid, whereas in the third

condition, the two kinds of flow patterns were overlaid with a depth separation produced by

binocular disparity. The subjects perceived both kinds of vection simultaneously in directions

opposite to those of the corresponding flow components under the first condition, whereas

either vection occurred mainly under the second condition. Under the third condition, both of

the flows induced each kind of vection simultaneously, despite there being no physical vector-

summation of dot motion. The background flow induced vection in a direction opposite to the

flow direction, whereas the foreground flow induced vection in the same direction as the flow

direction. These results show that induced self-translation and induced self-rotation can occur

simultaneously in two ways.



Iwabuchi, A. and H. Shimizu (1997). “Antiphase flicker induces depth segregation.” Perception &

Psychophysics 59(8): 1312-1326.

We examined the influence of the temporal phase of flickering stimuli on perceptual

organization. When two regions of a uniform random-dot field are flickered in temporal

alternation with the same flicker rate, one of the regions appears to lie in front of the other.

Within the range of temporal frequencies used in the present experiments, depth perception

was maximal between 5 and 31.3 Hz. Which region of the two is perceived as lying in front is

different from person to person and sometimes fluctuates within the same subject, but when

two regions are of different sizes, the smaller region tends to be perceived in front for longer

than the larger region. The depth segregation was not due to a luminance difference, because

the average temporal luminance of the regions-was kept equal. Strikingly, the illusory depth

segregation is perceived even between two adjacent regions whose densities of dots, sizes,

shapes, and flicker rates are identical. This result suggests that a difference of temporal phase

between two flickering regions is crucial for this new depth perception.



Jakes, S. and D. R. Hemsley (1986). “Individual differences in reaction to brief exposure to unpatterned

visual stimulation.” Personality and Individual Differences 7(1): 121-123.

Exposed 11 Ss (mean age 36.8 yrs) for 10 min to a changing random pattern of dots on a

visual display screen. Ss were instructed to report visual patterns they perceived into a tape

recorder. Ss also completed the Hallucinatory Predisposition Scale (HPS) and the Eysenck

Personality Questionnaire (EPQ). Results indicate that the number of reports of complex

patterns correlated significantly both with the Psychopathology and Neuroticism scales of the

EPQ and with the HPS. (14 ref) (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 661 of 887 in PsycINFO 1985-1987



Janssen, P., R. Vogels, et al. (2003). “At least at the level of inferior temporal cortex, the stereo

correspondence problem is solved.” Neuron 37(4): 693-701.

Stereoscopic vision requires the correspondence problem to be solved, i.e., discarding "false"

matches between images of the two eyes, while keeping correct ones. To advance our

understanding of the underlying neuronal mechanisms, we compared single neuron responses

to correlated and anticorrelated random dot stereograms (RDSs). Inferior temporal neurons,

which respond selectively to disparity-defined three-dimensional shapes, showed robust

selectivity for correlated RDSs portraying concave or convex surfaces, but unlike neurons in

areas V1, MT/V5, and MST, were not selective for anticorrelated RDSs. These results show

that the correspondence problem is solved at least in far extrastriate cortex, as it is in the

monkey's perception.



Janssen, P., R. Vogels, et al. (1998). “Assessment of stereopsis in rhesus monkeys using visual evoked

potentials.” Documenta Ophthalmologica 95(3-4): 247-255.

Rhesus monkeys can have deficiencies in stereo vision, making it necessary to screen monkey

subjects intended for single cell studies of stereo-based depth processing. We measured VEPs

in two monkeys using a dynamic random-dot display in which a stereo-defined checkerboard

reversed in depth. Monkeys fixated upon a small dot during stimulus presentation. One

monkey showed clear evoked potentials in response to changes in disparity that were similar

to those obtained in human subjects, using an identical stimulus paradigm. Controls with

presentations of the monocular stimulus sequences (in which no depth reversal can be

perceived) yielded no or much weaker VEPs. In the other animal, however, there was no

difference in evoked potential between the two conditions. These electrophysiological findings

closely match the performance of these same two subjects in a disparity discrimination task in

which they were previously trained. We conclude that VEPs using this type of stimulus disp

lay can be used to screen monkeys for single cell or behavioral studies of stereopsis.



Jeffrey, B. G., E. E. Birch, et al. (2001). “Early binocular visual experience may improve binocular

sensory outcomes in children after surgery for congenital unilateral cataract.” Journal of

Aapos 5(4): 209-216.

Purpose: To compare the effect of intensive and reduced occlusion therapy regimens on

binocular sensory outcomes, visual acuity, and the prevalence of strabismus in children after

surgery for congenital unilateral cataract. Methods:Two nonrandomized groups of patients

were studied prospectively: (1) an intensive occlusion group (n = 29) patched 80% of waking

hours were followed for a median 6.9 years and (2) a reduced occlusion group (n = 8) patched

25% to 50% of waking hours were followed for a median 4.3 years. Six subjects in the

intensive group and 4 in the reduced occlusion group had secondary intraocular lenses. Two

subjects in the intensive group had epikeratophakia surgery. Binocular sensory function was

assessed with random dot and contour stereoacuity tests and the Worth 4-dot test. The

prevalence and age at onset of strabismus were determined from the patients' charts. Results.

A higher proportion of subjects in the reduced occlusion group (50%) had stereoacuity or

fusion compared with the intensive occlusion group (14%), a borderline significant difference

(P=.08). No significant difference (P=.55) was found in median visual acuity between the

intensive (20/50) and the reduced occlusion (20/55) groups. The 90% prevalence of strabismus

in the intensive occlusion group was slightly higher than the 63% prevalence in the reduced

occlusion group, although this difference was not significant (P=.18). Conclusions: These

results suggest that a reduced occlusion protocol may be associated with better binocular

sensory outcomes and a reduced prevalence of strabismus without compromising good visual

acuity in children treated for congenital unilateral cataract.



Jeka, J., K. S. Oie, et al. (2000). “Multisensory information for human postural control: integrating

touch and vision.” Experimental Brain Research 134(1): 107-125.

Despite extensive research on the influence of visual, vestibular and somatosensory

information on human postural control, it remains unclear how these sensory channels are

fused for self-orientation. The focus of the present study was to test whether a linear additive

model could account for the fusion of touch and vision for postural control. We

simultaneously manipulated visual and somatosensory (touch) stimuli in five conditions of

single- and multisensory stimulation. The visual stimulus was a display of random dots

projected onto a screen in front of the standing subject. The somatosensory stimulus was a

rigid plate which subjects contacted lightly ( 7. (17 ref) (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 858 of 887 in PsycINFO 1967-1977



Julesz, B. and W. Kropfl (1982). “Binocular neurons and cyclopean visually evoked potentials in

monkey and man.” Annals of the New York Academy of Sciences 388: 37-44.

Reviews studies of visually evoked potentials (VEPs) elicited by random-dot stereograms and

correlograms (also called cyclopean stimuli). These procedures allow examination of VEPs

under pure conditions, since cyclopean stimuli operationally bypass several early processing

stages in the retinal-thalamic-cortical pathway and provide an unfakeable test for functional

binocularity or stereopsis in animals, human infants, and patients with optical pathway defects

in the absence of verbal communication. Consideration is given to the role of VEP research in

psychology-neuropsychology linking hypotheses and the clinical implications of cyclopean

VEPs. A brief discussion of this paper is appended. (18 ref) (PsycINFO Database Record (c)

2002 APA, all rights reserved) Record 742 of 887 in PsycINFO 1978-1984



Julesz, B., W. Kropfl, et al. (1980). “Large Evoked-Potentials to Dynamic Random-Dot Correlograms

and Stereograms Permit Quick Determination of Stereopsis.” Proceedings of the National

Academy of Sciences of the United States of America-Biological Sciences 77(4): 2348-2351.



Julesz, B. and J. E. Miller (1975). “Independent spatial-frequency-tuned channels in binocular fusion

and rivalry.” Perception 4(2): 125-143.

Random-dot stereograms were bandpass filtered in the 2-dimensional Fourier domain, and

masking noise of various spatial frequency bands was added to the filtered stereograms.

Masking noise bands containing equally effective noise energy were selected such that their

bands were either overlapping with the stereoscopic image spectrum or were 2 octaves distant.

The 1st case resulted in binocular rivalry; however, in the 2nd case stereoscopic fusion could

be maintained in the presence of strong binocular rivalry owing to the masking noise. This

finding indicates that spatial-frequency-tuned channels are not restricted to 1-dimensional

gratings but operate on 2-dimensional patterns as well. Furthermore, these frequency channels

are utilized in stereopsis and work independently from each other, since some of these

channels can be in binocular rivalry while at the same time other channels yield fusion. The

main binocular experiments are demonstrated. (23 ref) (PsycINFO Database Record (c) 2002

APA, all rights reserved) Record 842 of 887 in PsycINFO 1967-1977



Julesz, B. and H. P. Oswald (1978). “Binocular utilization of monocular cues that are undetectable

monocularly.” Perception 7(3): 315-322.

The latency of tracking dynamic random-dot stereograms can be shortened by as much as 100

msec when monocular cues are added by introducing a difference in dot density between

target and surround. It has been tacitly assumed that perception time will be reduced only if

the added monocular cues are above the detection threshold for each eye. However, the

experiments reported here clearly show that stereoscopic performance as measured by an eye

tracking task can be greatly enhanced by added monocular cues that cannot be detected. Two

observers were instructed to track a suddenly displaced vertical bar (portrayed as a dynamic

random-dot stereogram) while their eye movements were recorded by EOG. The bar had

either a given binocular disparity or zero binocular disparity with respect to its surround. For

the target with a disparity (in a wide range), the latency time of tracking decreased by more

than 30 msec (10%) as density differences increased from 0 to 4%, whereas in the control

conditions with no stereoscopic cues (zero disparity) Ss were unable to track the bar at all

within that range of density difference. Thus stereopsis is greatly aided by minimal monocular

cues that by themselves elude monocular detection. (14 ref) (PsycINFO Database Record (c)

2002 APA, all rights reserved) Record 806 of 887 in PsycINFO 1978-1984



Kahn, J. I. and D. H. Foster (1981). “Visual Comparison of Rotated and Reflected Random-Dot

Patterns as a Function of Their Positional Symmetry and Separation in the Field.” Quarterly

Journal of Experimental Psychology Section a-Human Experimental Psychology 33(MAY):

155-166.



Kahn, J. I. and D. H. Foster (1986). “Horizontal-vertical structure in the visual comparison of rigidly

transformed patterns.” Journal of Experimental Psychology: Human Perception and

Performance 12(4): 422-433.

Investigated the proposal that visual recognition of patterns reflected or rotated through 180||

(point-inverted) depends critically on their positional symmetry and separation in the field. A

possible explanatory scheme suggested a description of internal pattern representation

structures and simple internal operations that naturally involved a horizontal-vertical reference

system. Predictions of the scheme were tested in 3 experiments, using 18 Ss (aged 21-27 yrs).

Ss made same^different judgments on pairs of random-dot patterns briefly presented in

various arrangements and related by reflection, point-inversion, or identity transformation, or

paired at random. Exp I tested reflected patterns and verified the importance of orientation of

the reflection axis relative to display-configuration axis. Exp II demonstrated an oblique effect

of configuration on performance with reflected patterns but not with identical or point-

inverted patterns. Exp III demonstrated a vertical shift effect of configuration on performance

with point-inverted patterns but not with identical or reflected patterns. (48 ref) (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 655 of 887 in PsycINFO 1985-

1987



Kaneko, H. and I. P. Howard (1996). “Relative size disparities and the perception of surface slant.”

Vision Research 36(13): 1919-1930.

Perceived slant produced by size disparities in random-dot displays was measured by tactile

matching. For a 60 deg surface, slant produced by vertical-size disparity (the induced effect)

was opposite to that produced by horizontal-size disparity. Overall-size disparity produced a

little slant. With small displays, effects of horizontal and vertical disparities were reduced but

not those of overall disparity, A zero-disparity surround increased effects of horizontal and

overall disparities but reduced the induced effect. A mixture of horizontally disparate and

zero-disparity dots produced two slanted surfaces. Vertically disparate and zero-disparity dots

produced one slanted surface, Abutting opposite horizontal disparities produced surfaces with

a sharp boundary, Abutting vertical disparities produced surfaces with a gradual boundary,

Perceived slant depends on the difference between horizontal-size disparity detected locally

and mean vertical-size disparity over a relatively large area. Copyright (C) 1996 Elsevier

Science Ltd.

Kaneko, H. and I. P. Howard (1997). “Spatial properties of shear disparity processing.” Vision

Research 37(3): 315-323.

We investigated whether vertical-shear disparity was extracted from the whole visual field or

from a more local area and how global estimates of vertical disparity are derived, We also

investigated the role of cyclovergence in processing shear disparity, Random-dot stereoscopic

displays in various configurations were presented with horizontal-shear disparity, vertical-

shear disparity or same-sign horizontal- and vertical-shear (rotation) disparity. Vertical-shear

disparity introduced into only the right half of a 60 deg-wide display produced perceived

inclination of the whole display when the center of shear was on the fovea, but did not

produce inclination, either of the whole display or of a local area when the centre of shear was

in an eccentric retinal position, A display containing dots with vertical-shear disparity mixed

with dots with zero-disparity produced one inclined surface, Horizontal-shear disparity always

produced inclination confined to the local area of disparity, Rotation disparity produced no

inclination when introduced into the whole display, but when introduced with zero-disparity

dots it produced an inclined plane distinct from the plane defined by the zero-disparity dots,

These results could be attributed to cyclovergence, which we therefore eliminated in our last

experiment. We conclude that the perception of surface inclination is based on the difference

between local horizontal-shear disparity and global vertical-shear disparity averaged over the

whole visual field. Copyright (C) 1996 Elsevier Science Ltd



Kanizsa, G., P. Kruse, et al. (1994). “Conditions of visibility of actual paths.” Japanese Psychological

Research 36(3): 113-120.

Reports on studies of perception demonstrating that when dots move along circular, partially

overlapping paths, the observer succeeds in detecting the circular motion only when the

average distance of each dot from the other dots of the same path (SP) is minor to the average

distance of each dot from the dots of the other paths (OPs). It was hypothesized that if SP is

clearly minor to OP the relative motion emerges, and when there is a nonclear difference

between OP and SP, no clear perceptual organization emerges. The hypothesis was supported

in 2 experiments of 16 university students each (aged 19-27 yrs). The results are discussed in

terms of the theory of praegnanz and of synergetics.



Kano, C. (1991). “The perception of self-motion induced by peripheral visual information in sitting and

supine postures.” Ecological Psychology 3(3): 241-252.

Studied the effects of speed and direction of a moving peripheral stimulus on the perception of

self-motion in 21 adults in sitting and supine postures. Ss sat or lay on their backs with one

monitor on each side of their head. On the monitor screens, random dot patterns moved

vertically or horizontally under 3 speed conditions. The latency of the onset of the induced

self-motion was shorter under the high-speed condition than under the lower speed conditions.

In the sitting posture, the latency was shorter when the patterns moved vertically than when

they moved horizontally. In the supine posture, the latency was shorter when the self-motion

was perceived egocentric downward toward the feet and gravitationally downward toward the

back of the Ss. Results suggest that information from the vestibular system is different for

sitting and supine postures. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 532 of 887 in PsycINFO 1990-1992



Kano, M., K. Iino, et al. (1991). “Optokinetic Response of Cells in the Nucleus-Reticularis Tegmenti

Pontis of the Pigmented Rabbit.” Experimental Brain Research 87(2): 239-244.

In immobilized pigmented rabbits anesthetized with N2O (70%) and halothane (2-4%),

extracellular spikes were recorded from neurons in the nucleus reticularis tegmenti pontis

(NRTP) and their responses to optokinetic stimulation (OKS) were examined. OKS was

delivered using constant-velocity (0.1-4.0-degrees/s) movements of a random dot pattern (60-

degrees x 60-degrees) at 0-degrees, 45-degrees, 90-degrees or 135-degrees to the horizon.

With OKS delivered to the contralateral eye (n = 43), the preferred directions of NRTP cells

were forward (F, n = 10), backward (B, n = 7), downward (D, n = 5), and the remaining cells

showed no response (N, n = 21). With OKS delivered to the ipsilateral eye (n = 43), the

preferred directions were F (n = 8), B (n = 8), upward (U, n = 2), D (n = 1) and N (n = 24).

The majority of cells which responded to OKS (17/22 for contralateral, and 16/19 for

ipsilateral OKS) preferred the horizontal orientation. The optimum velocity ranged from 0.2 to

1-degrees/s. The results suggest that the NRTP cells mainly transfer horizontal optikinetic

signals to the flocculus and control horizontal optokinetic eye movements.



Kansaku, K., K. Hashimoto, et al. (2001). “Retinotopic hemodynamic activation of the human V5/MT

area during optokinetic responses.” Neuroreport 12(18): 3891-3895.

To detect retinotopic activation in the human V5/MT, we obtained fMRI signals during

optokinetic responses (OKR). We used two types of patterns, consisting of random dots

plotted in either the central or peripheral regions, to stimulate the central and peripheral visual

fields, respectively. These patterns moved at a constant speed of 20 degrees /s rightward and

leftward alternately. Subjects were required to track the patterns with their eyes. The two types

of visual stimuli elicited different patterns of brain activation; the area with the most

significant response to central visual field stimuli was located posteriorly to that responding to

peripheral visual field stimuli. NeuroReport 12:3891-3895 (C) 2001 Lippincott Williams &

Wilkins.



Kapoula, Z., M. P. Bucci, et al. (1996). “Fast disconjugate adaptations of saccades in microstrabismic

subjects.” Vision Research 36(1): 103-108.

In normal subjects, saccade amplitude inequality can be induced almost immediately when the

image is made larger for one eye. This disconjugacy allows binocular fusion at the point of

regard despite the image size inequality. It persists under subsequent monocular viewing

which suggests a fast adaptive mechanism. This study tests whether such disconjugacy can be

induced in subjects with microstrabismus who do not have foveal fusion. Three

microstrabismic subjects viewed a random dot pattern the size of which was 10% larger in one

eye. Within 40 sec horizontal saccades became larger in the eye viewing the larger image by

4-10%; the induced disconjugacy persisted under subsequent monocular viewing. Thus, fast

disconjugate adaptation is possible in microstrabismus demonstrating that foveal fusion is not

necessary to achieve it.



Kapoula, Z., D. A. Robinson, et al. (1993). “Visually Induced Cross-Axis Postsaccadic Eye Drift.”

Journal of Neurophysiology 69(4): 1031-1043.

1. It has been previously shown that, if a visual pattern is transiently moved just after every

saccade, it is possible to induce horizontal, postsaccadic, ocular drift after horizontal saccades

that persists in the dark. In this study we show that horizontal ocular drift can also be created

after vertical saccades. Five human subjects viewed binocularly the interior of a full-field

hemisphere filled with a random-dot pattern. They were encouraged to make frequent vertical

saccades. During training, eye movements were recorded by the electrooculogram. A

computer detected the end of every saccade and immediately moved the pattern to the left

after up saccades and right after down saccades. The motion was exponential, its amplitude

was 25% of the vertical component of the antecedent saccade, its time constant was 50 ms.

Before and after 2-3 h of training, movements of both eyes were measured by the eye-

coil/magnetic-field method while subjects were instructed to make vertical saccades in the

dark, in the presence of the movable adapting pattern, and between stationary targets for

calibration.2. After training (approximately 20,000 saccades) all subjects developed a zero-

latency, exponential ocular drift to the left after up saccades and to the right after down

saccades. The amplitude of the horizontal drift, expressed as a percentage of the vertical

component of the preceding saccade, was 2.7% in the dark. This rose to 10.2% in the presence

of the movable adapting stimulus. The latter rise is not due to visual following systems but to

a zero-latency increase in initial drift velocity.3. The horizontal drifts were usually unequal

between the two eyes, indicating the presence of disconjugate movements. We measured

intrasaccadic disconjugate horizontal movements of all subjects. In agreement with studies by

others of saccades in the light, we measured a divergence during up saccades (1.3-degrees)

and a convergence for down (0.4-degrees), but in this case for spontaneous saccades in the

dark. After training, these values increased for saccades in the dark but decreased in the light

in the presence of the adapting stimulus. These changes were largely idiosyncratic and

statistically significant in only a few subjects.4. The cross-axis postsaccadic drifts were

separated into their conjugate and disconjugate components. The disconjugate components

were small and idiosyncratic, and the means were small for saccades in the dark. The only

consistent trend was in the presence of the adapting stimulus where up saccades were often

followed by convergence. The presence of these vergence components do not interfere with

our conclusion that this paradigm demonstrated cross-axis plasticity in postsaccadic drift.5.

The induced drift was specific to the stimulus pattern. The horizontal induced drift became

smaller for oblique saccades, decreased as their vertical components became smaller, and

disappeared for horizontal saccades. There was no induced vertical drift after horizontal

saccades.6. We suggest a hypothesis of crossed innervation. During a vertical saccade,

horizontal burst neurons are known to be bilaterally coactivated by a signal presumably from

vertical burst neurons. Normally, these activities cancel each other to produce no net

horizontal movement. Thus the lack of a horizontal component would seem to be not passive

(no signal at all) but active and determined by a balance between opposing forces. The same

argument can be made for the step of innervation. Plastic modification of synapses between

the horizontal burst neurons and the horizontal neural integrator could therefore create, during

a vertical saccade, a step of innervation to horizontal motoneurons in the absence of a pulse.

This hypothesis, with the use of only demonstrable neural pathways, shows how one might

create a step of innervation without a pulse and thus a horizontal postsaccadic drift without a

horizontal saccade.



Kappers, A. M., S. F. te Pas, et al. (1991). “Detection of divergence in optical flow fields.” Journal of

the Optical Society of America A: Optics and Image Science 8(8): 227-235.

Determined the psychophysical thresholds for detection of divergence (expansion and

contraction) in optical flow fields in the presence of a translational component using sparse

random dot patterns as stimuli. Four stimulus categories were tested: pure divergence,

decreasing/increasing velocity along flow lines, divergence stimulus with straight parallel flow

lines and constant velocity along flow lines. Two Ss were presented with the stimuli and asked

to decide whether a contraction or an expansion was shown. Lifetime and number of dots,

translational velocity, and divergence were systematically varied and thresholds were

measured in separate sessions. Results show that lifetime and number of dots have a small

influence on psychophysical performance, divergence detection is independent of the

translational component, and direction of flow lines is not the only factor in divergence

detection. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 493 of 887

in PsycINFO 1990-1992



Kappers, A. M. L., S. F. T. Pas, et al. (1996). “Simulating the detection of first-order optical flow

components.” Vision Research 36(21): 3539-3547.

Thresholds for the detection of rotation and divergence in the presence of a translational

component in sparse random dot patterns are determined for human observers and two

computer algorithms. The algorithms only make use of local velocity directions and not of

local velocity magnitude (speed). The results show that psychophysical performance in this

task can be well described without the need of specialized mechanisms tuned to either rotation

or divergence. Possibly, integration of information over more than two frames occurs for low

velocities. For high velocities the correspondence problem seems to limit performance.

Copyright (C) 1996 Elsevier Science Ltd.



Kappers, A. M. L., S. F. Te Pas, et al. (1996). “Simulating the detection of first-order optical flow

components.” Vision Research 36(21): 3539-3547.

Determined the thresholds for the detection of rotation and divergence in the presence of a

translational component in sparse random dot patterns for human observers and 2 computer

algorithms. For comparisons with the algorithms, only data from the S who reached the

highest noise levels and had the widest range of measurable conditions were used. The

algorithms only made use of local velocity directions and not of local velocity magnitude

(speed). Results show that psychophysical performance in this task can be well described

without the need of specialized mechanisms tuned to either rotation or divergence. Possibly,

integration of information over more than 2 frames occurs for low velocities. For high

velocities the correspondence problem seems to limit performance. (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 313 of 887 in PsycINFO 1996-1997



Kappers, A. M. L., S. F. tePas, et al. (1996). “Detection of divergence in optical flow fields.” Journal of

the Optical Society of America a-Optics Image Science and Vision 13(2): 227-235.

Psychophysical thresholds for the detection of divergence (expansion and contraction) in the

presence of a translational component are determined. Stimuli consist of sparse random dot

patterns. Lifetime, number of dots, divergence, and translational velocity are varied over a

wide range. Moreover, the two major characteristics of a divergence pattern, namely, the

direction of and the velocity along the flow lines, are also varied independently. Lifetime and

number of dots have only a small influence on performance. Over a wide range the detection

of divergence is independent of the translational component. The results indicate that the

direction of flow lines is an important, but by no means the only, characteristic in divergence

detection. This provides evidence that, at least in these experiments, no use is made of a

mechanism selectively sensitive for divergence. (C) 1996 Optical Society of America



Kappers, A. M. L., A. J. van Doorn, et al. (1994). “Detection of vorticity in optical flow fields.” Journal

of the Optical Society of America A: Optics and Image Science 11(1): 48-54.

Determined psychophysical thresholds for detection of vorticity in the presence of a

translational component in an experiment with 2 emmetropic and 1 myopic (corrected to

normal) females. Stimuli were sparse random-dot flow patterns. Detection of vorticity depends

critically on the translational component. The curvature of the flow lines, however, cannot be

the only factor limiting performance. In comparison with an ideal detector, it was found that

for small vorticities Ss typically used the stimulus information in an optimal manner. For

higher vorticities performance was worse, possibly owing to matching problems. Lifetime and

number of dots had little influence on performance. Although this indicates that human

observers can already perform the task by using only local information, it does not imply that

global information is disregarded. If the stimulus is disturbed locally, global information is

used to full extent. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record

461 of 887 in PsycINFO 1993-1995



Kappers, A. M. L., A. J. Vandoorn, et al. (1994). “Detection of Vorticity in Optical-Flow Fields.”

Journal of the Optical Society of America a-Optics Image Science and Vision 11(1): 48-54.

Psychophysical thresholds for the detection of vorticity in the presence of a translational

component are determined for human observers. Stimuli consist of sparse random-dot flow

patterns. The detection of vorticity depends critically on the translational component. The

curvature of the flow lines, however, cannot be the only factor limiting human performance.

On the basis of a comparison with an ideal detector, it is found that for small vorticities ( 10 ms before the eye movements.3. The relationship between the latency of neuronal

responses and that of eye movements was studied in 59 neurons by changing the stimulus

speed systematically (10-160 degrees/s). The latencies of both neuronal and ocular responses

decreased as stimulus speed increased. As a result, the time difference between the response

latencies for neuronal and ocular responses varied little with changes in stimulus speed.4.

Blurring of the random dot pattern, by interposing a sheet of ground glass, increased the

latency of both neuronal responses and eye movements.5. With the use of a check pattern

instead of random dots, both neuronal and ocular responses began to decrease rapidly when

the temporal frequency of the visual stimulus exceeded 20 Hz. At 40 Hz the neurons showed a

distinctive burst-and-pause firing pattern, and the eye movements showed signs of

oscillation.6. The response properties of the MST neurons during ocular following were

similar to those of the dorsolateral pontine nucleus (DLPN) neurons, reported previously. Our

results indicate that the MST neurons may provide visual information to the DLPN neurons

and may play a role in eliciting ocular following.7. Responses during smooth-pursuit eye

movement were studied in 55 MST neurons. Each of these neurons responded to the moving

large-field visual stimulus, which elicited ocular following, and 40 of these neurons were

activated during smooth pursuit in the dark. Response latencies during smooth pursuit were

long in those neurons having different directional preferences during smooth pursuit and

ocular following but were short for those having the same directional preferences during

smooth pursuit and ocular following. For the latter the response latency during smooth pursuit

was always longer than that during ocular following. These neurons may provide visual

information to the same type of DLPN neurons during both ocular following and smooth

pursuit.8. We observed responses of 11 MST neurons, which responded during smooth

pursuit, when the pursuit target was briefly turned off. In every case, target blinking reduced

their responses and their smooth-pursuit eye velocity. This was seen much earlier in the

neuronal responses than in the eye-velocity profile. The decrease in firing frequency of the

MST neurons may be due to disappearance of the target (visually induced), rather than to

feedback from eye velocity.



Kawano, K., M. Shidara, et al. (1992). “Neural Activity in Dorsolateral Pontine Nucleus of Alert

Monkey During Ocular Following Responses.” Journal of Neurophysiology 67(3): 680-703.

1. Movements of the visual scene evoke short-latency ocular following responses. To study

the neural mediation of the ocular following responses, we investigated neurons in the

dorsolateral pontine nucleus (DLPN) of behaving monkeys. The neurons discharged during

brief, sudden movements of a large-field visual stimulus, eliciting ocular following. Most of

them (100/112) responded to movements of a large-field visual stimulus with directional

selectivity.2. Response amplitude was measured in two components of the neural response: an

initial transient component and a late sustained component. Most direction-selective DLPN

neurons showed their strongest responses at high stimulus speeds (80-160-degrees/s), whether

their response components were initial (63/87, 72%) or sustained (63/87, 72%). The average

firing rates of 87 DLPN neurons increased as a linear function of the logarithm of stimulus

speed up to 40-degrees/s for both initial and sustained responses.3. Not only the magnitude but

also the latency of the neural and ocular responses were dependent on stimulus speed. The

latencies of both neural and ocular responses were inversely related to the stimulus speed. As

a result, the time difference between the response latencies for neural and ocular responses did

not vary much with changes of stimulus speed.4. Response latency was measured when a

large-field random dot pattern was moved in the preferred direction and at the preferred speed

of each neuron. Seventy-three percent (56/77) of the neurons were activated 10 ms before the eye

movements.5. Blurring of the random dot pattern by interposing a sheet of ground glass

increased the latency of both neural responses and eye movements. On the other hand, the

blurred images did not change the timing of the effect of blanking the visual scene on the

responses of the neurons or eye movements.6. When a check pattern was used instead of

random dots, both neural and ocular responses began to decrease rapidly when the temporal

frequency of the visual stimulus exceeded 20 Hz. When the temporal frequency of the visual

stimulus approached 40 Hz, the neurons showed a distinctive burst-and-pause firing pattern.

The eye movements recorded at the same time showed signs of oscillation, and their temporal

patterns were closely correlated to those of the firing rate.7. The results, that most DLPN

neurons changed their activities before eye movements and that their dependence on visual

properties of the stimulus was similar to that of ocular responses, suggest that they may play a

role in the mediation of visual information eliciting ocular following.8. Responses during

smooth pursuit eye movement were studied in 41 neurons, which responded to a moving

large-field visual stimulus that elicited ocular following. Twenty-eight (68%) of them were

activated during smooth pursuit in the dark. Latencies were long in neurons with opposite

directional preferences in smooth pursuit and ocular following (> 120 ms) but short in neurons

with the same directional preferences in both situations (60-90 ms). For the latter, the latency

of the response to the target spot was always longer than that of the response to the large-field

visual stimulus, and the neural response latency was shorter than the ocular response latency.

They may play a role in both ocular following and smooth pursuit.



Kebeck, G. (1987). “Der relative Einflu[s von Groe[se- und Dichtegradient auf die Wahrnehmung

raeumlicher Tiefe in Bildern. / The relative influence of size gradient and density gradient in

the perception of spatial depth in pictures.” Gestalt Theory 9(2): 57-69.

Studied the relative influence of 2 texture gradients (size and density) on the perception of

spatial depth in pictures. Human subjects: 54 normal male and female German adolescents and

adults (university students). The Ss were assigned to 1 of 3 experimental conditions and asked

to compare pairs of random dot patterns with regard to (1) depth, (2) distance to a marked

point (with a focus on the size gradient), or (3) distance to a marked point (with a focus on the

density gradient). (English abstract) (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 618 of 887 in PsycINFO 1985-1987



Kelly, D. M., W. F. Bischof, et al. (2001). “Detection of glass patterns by pigeons and humans:

Implications for differences in higher-level processing.” Psychological Science 12(4): 338-

342.

Glass patterns have been used to examine mechanisms underlying form perception. The

current investigation compared detection of glass patterns by pigeons and humans and

provides evidence for substantial species differences in global form perception. Ss were

required to discriminate, on a simultaneous display, a random dot pattern from a Glass pattern.

Four different randomly presented glass patterns were used (concentric-, radial, parallel-

vertical, and parallel-horizontal). Detection thresholds were measured by degrading the glass

patterns through the addition of random noise. For both humans and pigeons, discrimination

decreased systematically with the addition of noise. Humans showed detection differences

among the four patterns, with lowest thresholds to radial and concentric patterns and highest

thresholds to the parallel-horizontal pattern. Pigeons did not show a detection difference

across the four patterns. Implications for differences in neural processing of complex forms

are discussed. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 112 of

887 in PsycINFO 2001 Part A



Kelly, D. M., W. F. Bischof, et al. (2001). “Detection of glass patterns by pigeons and humans:

Implications for differences in higher-level processing.” Psychological Science 12(4): 338-

342.

Glass patterns have been used to examine mechanisms underlying form perception. The

current investigation compared detection of Glass patterns by pigeons and humans and

provides evidence for substantial species differences in global form perception. Subjects were

required to discriminate, on a simultaneous display, a random dot pattern from a Glass pattern.

Four different randomly presented Glass patterns were used (concentric, radial, parallel-

vertical, and parallel-horizontal). Detection thresholds were measured by degrading the Glass

patterns through the addition of random noise. For both humans and pigeons, discrimination

decreased systematically with the addition of noise. Humans showed detection differences

among the four patterns, with lowest thresholds to radial and concentric patterns and highest

thresholds to the parallel-horizontal pattern. Pigeons did not show a detection difference

across the four patterns. Implications for differences in neural processing of complex forms

are discussed.



Kersten, D., H. H. Bulthoff, et al. (1992). “Interaction between Transparency and Structure from

Motion.” Neural Computation 4(4): 573-589.

It is well known that the human visual system can reconstruct depth from simple random-dot

displays given binocular disparity or motion information. This fact has lent support to the

notion that stereo and structure from motion systems rely on low-level primitives derived from

image intensities. In contrast, the judgment of surface transparency is often considered to be a

higher-level visual process that, in addition to pictorial cues, utilizes stereo and motion

information to separate the transparent from the opaque parts. We describe a new illusion and

present psychophysical results that question this sequential view by showing that depth from

transparency and opacity can override the bias to see rigid motion. The brain's computation of

transparency may involve a two-way interaction with the computation of structure from

motion.



Khotanzad, A., A. Bokil, et al. (1993). “Stereopsis by Constraint Learning Feedforward Neural

Networks.” Ieee Transactions on Neural Networks 4(2): 332-342.

This paper presents a novel neural network (NN) approach to the problem of stereopsis. The

correspondence problem (finding the correct matches between pixels of the epipolar lines of

the stereo pair from amongst all the possible matches) is posed as a noniterative many-to-one

mapping. Two multilayer feed-forward NN's are utilized to learn and code this nonlinear and

complex mapping using the back-propagation learning rule and a training set. The first NN is

a conventional fully connected net while the second one is a sparsely connected NN with a

fixed number of hidden layer nodes. Three variations of the sparsely connected NN are

considered. The important aspect of this technique is that none of the typical constraints such

as uniqueness and continuity are explicitly imposed. All the applicable constraints are learned

and internally coded by the NN's enabling them to be more flexible and more accurate than the

existing methods. The approach is successfully tested on several random-dot stereograms. It is

shown that the nets can generalize their learned mappings to cases outside their training sets

and to noisy images. Advantages over the Marr-Poggio algorithm are discussed and it is

shown that the NN's performances are superior.



Kikuchi, M. and K. Fukushima (1996). “Neural network model of the visual system: Binding form and

motion.” Neural Networks 9(8): 1417-1427.

We propose a neural network model of the visual system of the brain which processes

different kinds of attributes such as form and motion in parallel. The model has two separate

channels. a channel processing form and a channel processing motion. Each channel has both

forward and backward connections, and exhibits selective attention. The selective attention

mechanism, however, does not work independently because of the interaction of the two

channels, which occurs at their lower layers. Both channels always focus attention on the same

object even when many objects are presented simultaneously to the input layer of the model.

The model was simulated on a computer. several objects made of moving random dots were

applied to the input layer. At first the model focused attention on one of the objects, and

detected its form and motion. It then processed the rest of the objects in turn by switching

attention. Copyright (C) 1996 Elsevier Science Ltd.



Kikuchi, T. (1981). “Effects of dot density and duration of mask stimulus upon visual backward

masking.” Japanese Psychological Research 23(1): 37-42.

Four Ss, with normal or corrected to normal vision, performed a visual masking task. Mask

effectiveness was measured in terms of critical interstimulus intervals, varying dot density,

and duration of the mask. The resulting curves were inverted U-shaped functions of random

dot density, indicating that the maximal effectiveness of the mask was obtained at about 50%

dot density. As the mask duration increased, the U-shaped curves became more symmetrical.

This effect was primarily due to an increase in the masking magnitude at lower dot-density

levels. At higher dot-density levels, the mask effectiveness was nearly constant for mask

durations of 5 msec or longer, depending upon dot density. Results suggest that a main factor

of this type of masking is confusion in a composite perceptual image that contains a

representation of both the target and the mask. (14 ref) (PsycINFO Database Record (c) 2002

APA, all rights reserved) Record 758 of 887 in PsycINFO 1978-1984



Kikuchi, T. (1987). “Temporal characteristics of visual memory.” Journal of Experimental Psychology:

Human Perception and Performance 13(3): 464-477.

In order to infer the temporal relations among iconic, short-term, and long-term components of

visual memory, random dot patterns were used as memory stimuli in six recognition memory

experiments. Experiment 1 demonstrated that recognition was still above chance for intervals

up to 12 s. In Experiments 2 and 3, an intervening masking stimulus was found to be effective

only if presented within the first 500 ms of the interval. The remaining three experiments

employed a two-target task, with the second target replacing the masking stimulus.

Recognition performance with the second target was the same as that in a single-target task,

whereas performance with the first target was almost at chance level. Increasing the interval

between the targets resulted in a gradual improvement in the recognition of the first target.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 646 of 887 in

PsycINFO 1985-1987



Kim, Y. G. and J. D. Mollon (2002). “Conditions under which stereopsis and motion perception are

blind.” Perception 31(1): 65-71.

We describe modified random-dot stereograms in which the corresponding elements differ

from non-corresponding elements in colour, size, and luminance. Despite these visible

differences between the elements, depth perception collapses when the spatially integrated

luminous flux is similar for the corresponding and non-corresponding elements. Our results

suggest that a low-pass spatial filter precedes the mechanism that recognises disparity. A.

similar phenomenon is observed for the perception of coherent motion in random-dot

kinematograms. Our modified stereograms and kinematograms may find other uses when

experimenters wish to study the contribution of colour to visual processes and require a

method of eliminating edge artifacts.



Kimerling, A. J. (1989). “Predicting Dot Coverage for Colored Areas Produced by Single and Multiple

Pixel Random Dots.” American Cartographer 16(1): 17-27.



Kimmig, H. G., F. A. Miles, et al. (1992). “Effects of stationary textured backgrounds on the initiation

of pursuit eye movements in monkeys.” Journal of Neurophysiology 68(6): 2147-2164.

The electromagnetic search coil technique was used in 4 rhesus monkeys to record the initial

ocular pursuit of small target spots that suddenly start to move at a constant speed. The effects

of dichotic presentation of the track target and the possibility of interocular transfer were also

studied. Ss visually fixated on a red dot presented against a variety of backgrounds. Stationary

textured backgrounds reduced the initial eye acceleration (EA) achieved during pursuit but did

not affect its latency. A textured background seen by only 1 eye reduced the EA achieved

during the initial pursuit of moving targets seen only by the other eye, thus indicating

interocular transfer. In a background of random dots, shifting the target out of the plane of the

background reduced the impact of that background on the initiation of pursuit. (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 500 of 887 in PsycINFO 1990-

1992



Kimmig, H. G., F. A. Miles, et al. (1992). “Effects of Stationary Textured Backgrounds on the

Initiation of Pursuit Eye-Movements in Monkeys.” Journal of Neurophysiology 68(6): 2147-

2164.

1. The initial ocular pursuit of small target spots (0.25-degrees diam) that suddenly start to

move at constant speed (ramps) was recorded in four rhesus monkeys with the electromagnetic

search coil technique. All target motions were horizontal, and both eyes were monitored.2. In

agreement with the observations of Keller and Khan, stationary textured backgrounds

substantially reduced the initial eye acceleration achieved during pursuit but did not affect its

latency. Correlation techniques were used to assess the changes in the eye speed profiles and

indicated that the reduction in eye acceleration due to the background was a linear function of

the logarithm of target speed over the range investigated (5-40-degrees/s), averaging 60% with

the fastest targets.3. Selectively excluding the background texture from the path of the target

with a horizontal strip of card (vertical width, 4-degrees) reduced the impact of the

background only slightly, and, even when the vertical width of the card was increased to 60-

degrees, the effect of the background was not entirely eliminated. Thus the effect involves

regions of the visual field well beyond the target and is not due simply to the reduced physical

salience (contrast) of the target spot. Such spatially remote interactions suggest that the

neurons decoding the target's motion have ver-v extensive visual receptive fields.4. Textured

backgrounds also caused similar reductions in the eye acceleration during initial pursuit when,

before the ramps, the fixated target spots stepped forward, i.e., stepped in the direction of the

subsequent ramps (step ramps). In this situation, as with no steps, initial target ramps were

foveofugal. When the fixated target spots were stepped back before moving forward so that

initial target ramps were foveopetal, textured backgrounds now also delayed the onset of

pursuit, and the reductions in eye acceleration were not seen until some time later when

tracking resulted from foveofugal target-ramp motion. Selectively excluding the texture from

the path of the target with a narrow strip of card eliminated any delays in the onset of pursuit

to step ramps, but the later reductions in eye acceleration were still evident. These step-ramp

data indicate that the mechanisms decoding foveofugal and foveopetal target ramps differ

markedly in their sensitivity to textured backgrounds. That backgrounds can influence the

latency and the initial eye acceleration independently is consistent with the idea that there are

independent trigger and drive mechanisms for the decoding of target motions.5. A textured

background seen only by one eye reduced the eye acceleration achieved during the initial

pursuit of moving targets seen only by the other eye: interocular transfer. The reduction in eye

acceleration in this situation averaged 61% of the reduction observed during normal binocular

viewing, indicating that a substantial part of the effect of the background must occur at a site

that receives inputs from both of the eyes and hence is mediated by the CNS.6. Untextured

backgrounds (Ganzfeld) seen only by one eve generally had minor effects on the initial pursuit

of moving targets seen only by the other eye except when the luminance of those backgrounds

was temporally modulated: brief (10-mus) flashes of the Ganzfeld during the initial target

motion caused an abrupt hesitation in the eye speed profile with a mean latency of 41 +/- 3

(SD) ms. Thus temporally or spatially modulated backgrounds can adversely affect the

initiation of pursuit, presumably reflecting the temporospatial characteristics of the neurons

decoding target motion.7. When the background consisted of random dots, shifting the target

out of the plane of the background (with the use of a special dichoptic viewing arrangement)

reduced the impact of that background on the initiation of pursuit. In this situation the monkey

probably sees the background images as both disparate (diplopic) and blurred and either (or

both) factors could be critical in determining the effect of the background. However, if the bac



Kincaid, W. M. and W. R. Uttal (1986). “The effect of 3-D orientation and stretches on the detection of

dotted planes.” Perception and Psychophysics 39(6): 392-396.

Used a masking procedure in which a dotted stimulus form was masked by random dots to

explore form-detection capabilities of 4 undergraduates. The forms were located in a

stereoscopically generated 3-dimensional rectangular volume and were defined by a set of

randomly positioned dots always restricted to a plane. Both the apparent area and the apparent

dot density of the plane varied with orientation. For a constant number of stimulus-form and

masking dots, the detectability of the plane was shown not to depend on orientation. Findings

suggest that there is a range of conditions over which detectability depends only on the total

numbers of stimulus and masking dots and not on subjective orientation, density, or area of the

plane. Therefore, Ss respond as if they were sensitive to the retinal 2-dimensional density

rather than the apparent 3-dimensional density. (PsycINFO Database Record (c) 2002 APA,

all rights reserved) Record 645 of 887 in PsycINFO 1985-1987



Kingdom, F. A. A., H. C. O. Li, et al. (2001). “The role of chromatic contrast and luminance polarity in

stereoscopic segmentation.” Vision Research 41(3): 375-383.

We have investigated whether our ability to discriminate the stereoscopic depth of random-dot

targets set amongst random-depth distracters is facilitated when target and distracters differ in

particular combinations of colour and luminance polarity. For flat-plane targets, stereo-

thresholds were found to be lower with a target-distracter colour/luminance difference, but

only when that difference enabled the target elements to be identified in the monocular image,

either by virtue of being less numerous than the distracters. or because the subject knew

beforehand the target's colour/luminance. If neither of these conditions prevailed, stereoscopic

thresholds were no different when target and distracters were segregated by colour/luminance

than if they were not. For sine-wave disparity grating stimuli, in which subjects were required

to discriminate the orientation of the depth corrugations, no advantage was found when target

and distracters were segregated by colour,;luminance under any condition. These results

suggest that segregation by colour/luminance is only beneficial to the stereoscopic processing

of random-element stimuli when the task can be performed by attending to a small number of

target elements. A corollary to this conclusion is that stereopsis mechanisms do not

automatically pre-filter the image into different colour/luminance maps. (C) 2001 Elsevier

Science Ltd. All rights reserved.



Kingdom, F. A. A., D. R. Simmons, et al. (1999). “On the apparent collapse of stereopsis in random-

dot-stereograms at isoluminance.” Vision Research 39(12): 2127-2141.

We have investigated the apparent collapse of stereopsis obtained with random-dot-

stereograms at isoluminance. Contrast thresholds for both depth and form discrimination of

targets in random-dot- and figural stereograms were measured at a number of disparities,

using both isoluminant and isochromatic stimuli. All contrast thresholds for stereoscopic tasks

were normalised to contrast thresholds for detecting the appropriate stimulus. We found that at

isoluminance contrast thresholds for depth judgements were no higher for random-dot

compared to figural stereograms, even when normalised to the same thresholds obtained with

isochromatic stimuli. On the other hand contrast thresholds for three-dimensional form

judgements were much higher than those for depth judgements in isoluminant, compared to

isochromatic random-dot-stereograms. This specific impairment of stereoscopic form (as

opposed to depth) processing at isoluminance was confirmed in a further experiment in which

subjects were required to judge the presence and orientation of depth corrugations in a

disparity-modulated random-dot-stereogram. (C) 1999 Published by Elsevier Science Ltd. All

rights reserved.



Kirman, J. H. (1984). “Forward and backward tactile recognition masking.” Journal of General

Psychology 111(1): 83-99.

Forward and backward tactile recognition masking with a 15 by 15 array of tactile point-

stimulators was investigated with the use of targets consisting of line segments differing in

location and orientation and a random-dot embedding mask. Four paid graduate psychology

students were selected on the basis of initial testing. Durations of targets and masks were

varied, and interstimulus intervals of 0-300 msec were used. Results show that increases in

target duration over mask duration decreased forward, but not backward, masking. Small

increases in mask duration over target duration increased both forward and backward masking.

Further large increases in mask duration increased backward masking but had no effect on

forward masking. It is suggested that forward masking is predominantly influenced by

peripheral processes, while backward masking is the result of a combination of peripheral and

central processes. (20 ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 691 of 887 in PsycINFO 1978-1984



Kitama, T., M. Ishida, et al. (2001). “Difference between horizontal and vertical optokinetic nystagmus

in cats at upright position.” Japanese Journal of Physiology 51(4): 463-474.

The slow-phase velocity (SPV) of optokinetic nystagmus (OKN) and optokinetic after

nystagmus (OKAN) in response to a velocity step of surround rotation in the horizontal

direction is composed of the rapid and slow components in the cat: a rapid rise, a slow rise to a

steady state, a rapid fall, and a slow decline to 0 deg/s. The rapid and slow components are

attributed to the direct pathway and velocity storage neuronal mechanisms, respectively. The

difference between horizontal and vertical OKN has been reported in the monkey at the

upright position, but the slow and rapid components have not been distinguished. The present

study compared horizontal OKN-OKAN with vertical OKN-OKAN in the cat at the upright

position, distinguishing the rapid and slow components. Constant velocity rotation of a

random dot pattern at a velocity of 5 to 160 deg/s. was used for optokinetic stimulation. The

results: First, the amplitude of the rapid rise was relatively small in all SPV directions and all

stimulus velocities investigated, with a slight upward-SPV preference to the downward-SPV

(maximum 6.4, 6.0, and 3.4 deg/s. in horizontal, upward, and downward SPV direc tions,

respectively). Second, the steady state velocity was large during horizontal OKN (maximum

69.0 deg/s), small during upward-SPV OKN (12.9 deg/s), and missing (SPV is negligibly

small and irregular) during downward-SPV OKN, indicating a large directional difference of

OKN. Third, the acceleration of the slow rise decreased with the stimulus velocity at higher

stimulus velocities > 20 deg/s during both horizontal and upward-SPV OKN, suggesting

strong nonlinearity in the velocity charge system. Fourth, the decay time course of the OKAN

was described by the time constant of the exponential function, and the time constant was

longer during horizontal (mean, 8.3 s at a stimulus velocity of 20 deg/s) than during upward-

SPV (5.4 s) OKAN, suggesting that the velocity discharge system is relatively linear

compared with the velocity charge system. It is concluded that horizontal OKN-OKAN is

much larger than vertical OKN-OKAN in the cat at the upright position, and this directional

difference is caused mainly by the directional difference in the velocity storage mechanism,

but not in the direct pathway mechanism.



Kitazaki, M. (2001). “Perception of structure from motion influenced by adjacent occluders: The effect

of depth-order validity defined by binocular disparity.” Japanese Journal of Psychonomic

Science 20(1): 53-54.

It is reported that the structure-from-motion perception was influenced by the contour

configuration : the contour attributed to the moving-element edge modified/increased the

perceived depth, but that attributed to the outside frame as occluders had no effect. Thus, I

focused on the effect of the adjacent occluder. The subject rated perceived depth from the

random-dot motion simulating a cylinder with/without adjacent occluders. I manipulated the

depth curvature and the binocular disparity of the occluders. The perceived depth decreased

when the occluders were on accretion/deletion sides of dots comparatively with the condition

without occluders. However, there was little difference between disparity conditions. Thus, the

depth-order validity defined by binocular disparity was less effective than that by pictorial

information. (PsycINFO Database Record (c) 2004 APA, all rights reserved)(journal abstract)

Record 3 of 887 in PsycINFO Weekly 2004/03 Week 2



Kitazaki, M. and T. Sato (1999). “Depth curvature discrimination by binocular disparity.” Japanese

Journal of Psychonomic Science 18(1): 87-88.

The human visual system has an anistropy in sensitivity to the discrimination of depth

curvature defined by binocular disparity depending on modulation directions. Shear curvature

is easier to perceive than compressive curvature. The authors measured the performance for

concave-convex discrimination using a random-dot stereogram with varied duration and

density. Discrimination performance increased monotonically with duration increase for shear

curvature. For compressive curvature, however, the performance first peaked at a short

duration. It degraded for a while, and increased again at longer durations. The first peak

probably reflects the local processing of disparity, and the second increase might reflect the

global-integration processing. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 204 of 887 in PsycINFO 1999



Kitazaki, M. and S. Shimojo (1999). “Three-dimensional structure perception of paired-dot and

unpaired spherical surfaces: The effects of the vantage point and the object's rotation axis

predicted by the generic-view principle.” Japanese Journal of Psychonomic Science 18(1): 9-

22.

Examined the applicability of the generic-view principle to the extraction of structure from

motion. In particular the authors manipulated the angle between the line of sight and the

rotation axis of the spherical surface that was defined by moving paired or unpaired random

dots. Exp 1 examined the qualitative differences in depth effect among 3 image-motion types

on 4 male 21-26 yr olds. Exp 2 examined the effect of vantage-point shift amounts on depth in

1 female and 2 male Ss (aged 20-26 yrs). Exp 3 examined only the vertical elevation of the

vantage point using 4 male 21-27 yr olds. The generic image motions elicited clearer and more

depth than the accidental ones in the paired-dot stimuli, being mostly consistent with the

predictions of the generic-view principle. The effect of the generic image motion was less in

the unpaired-dot stimuli than in the paired-dot stimuli. The authors suggest that the

combination of the generic-view principle and the relative-motion hypothesis could better

explain perception of the rotating sphere in general. Thus, both seem to contribute to the

processing of structure from motion. (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 206 of 887 in PsycINFO 1999



Klar, M. and K. P. Hoffmann (2002). “Visual direction-selective neurons in the pretectum of the

rainbow trout.” Brain Research Bulletin 57(3-4): 431-433.

In mammals, the essential neuronal substrate for the generation of the horizontal optokinetic

nystagmus; (hOKN) are the nucleus of optical tract (NOT) and the dorsal terminal nucleus

(DTN). The medial terminal nucleus (MTN) is thought to be involved in vertical OKN

control. Characteristic for all of these neurons is a high-direction selectivity. Although

behavioural hOKN experiments in different fish species show comparability to mammals,

little is known about the neuronal OKN control in fish. In preceding studies, we demonstrated

that the rainbow trout has a nearly symmetrical monocular hOKN at low stimulus speeds.

With increasing visual stimulus speeds (> 14degrees/s), the monocular hOKN becomes

asymmetrical with a temporo to nasal preferred direction. For visual stimulation, we,

presented random-dot-patterns projected by a planetarium inside a perimeter. We tested four

rotation axes of the:planetarium, yaw (0degrees-180degrees), roll (90degrees-270degrees),

diagonal (45degrees-225degrees) and anti-diagonal (135degrees-315degrees). In every

position, the visual stimulus turned in clockwise and counter-clockwise direction. In a

subregion of the pretectum of nine fish, we recorded 47 direction-selective neurons. Analysis

of tuning-curves and preferred direction vectors show that these neurons encode both

horizontal (yaw) and vertical (roll) visual stimulus directions. These results suggest that the

control of horizontal and vertical OKN might not segregate into different nuclei in fish. (C)

2002 Elsevier Science Inc.



Klauer, S., F. Sengpiel, et al. (1990). “Visual Response Properties and Afferents of Nucleus of the

Optic Tract in the Ferret.” Experimental Brain Research 83(1): 178-189.

Basic properties of responses to visual stimulation with large moving random dot patterns

were studied in ferret nucleus of the optic tract. Retinal input to NOT was assessed by

orthodromic electrical stimulation of the optic chiasm and optic nerves. Presence of an input

from visual cortex was tested by orthodromic electrical stimulation of ipsilateral area 17. All

51 NOT neurons studied displayed a non-habituating, clearly direction-specific response:

discharge rate strongly increased with the stimulus pattern moving horizontally in ipsiversive

direction (motion directed towards the recorded hemisphere) and decreased with contraversive

stimulus motion. Most latencies to visual stimulation ranged from 80 to 100 ms. Velocity

tuning was studied using stimulus velocities between 4 deg/s and 100 deg/s. Discharge rates

were most effectively modulated at a stimulus velocity of 20 deg/s. A large portion of the cells

studied (91%) could be binocularly activated, although for almost all neurons the contralateral

eye was dominant. Through stimulation ot the optic chiasm 46 out of 51 NOT neurons could

be electrically activated with a latency of 5.42 +/- 0.66 ms (mean +/- SD). For 15 fibers

stimulated from both optic chiasm and contralateral optic nerve, conduction velocities

between 2.5 and 8.9 m/s, with a mean of 5.1 m/s, were obtained. A major direct input from the

ipsilateral retina was not found. Furthermore, 65% of all neurons could be activated through

electrical stimulation of visual cortex with a mean latency of 3.7 +/- 1.54 ms, indicating a

strong cortical projection to ferret NOT. The functional relevance of response properties of

ferret NOT neurons for horizontal optokinetic nystagmus is discussed. Parameters that could

be related to formation of corticopretectal projection in mammals are considered.



Kleinman, E. B. (1998). An investigation of the relationships among selected visual skills and

academic achievement at four different levels of learning.

The current study explores selected visual skills and their relationship to academic

achievement. Color vision, span of recognition, object size and the eliciting of meaningful

images from random dot/pattern visuals were compared with each other and with achievement

at four different levels of learning; (a) facts, (b) concepts, (c) rules/procedures, (d) problem

solving. Eighty-two undergraduate student volunteers completed both a computer program

that assessed their performance on visual skills and a paper-based booklet with information

about the human heart. The computer program presented the independent variables. Illustrated

hard copy booklets presented the dependent variable information. One half of the participants

randomly received color visuals with their heart content while the other half received

black/white visuals with their heart content. Four sets of 20 questions were given participants

after they studied the heart content. Each question set represented one of the achievement

levels. The scores from each set were the dependent variables. Pearson Product-Moment

Correlation coefficients were calculated and significant relationships were found between the

object size and span of recognition visual skills. Study results were analyzed also with

Analysis of Covariance, One way and Three Way Analyses of Variances and Two Sample T-

Tests. Significant results were evaluated further with Tukey procedures. Participants who

received color visuals obtained significantly higher scores on the heart content than those who

received the black/white visuals. Interactions among the visual skills reached significance

under some conditions. Main effects also reached significance for the random dot visual skill

at the concept, fact and problem solving levels. The results of the study confirmed the value of

including color visuals in instructional designs at specific learning levels and confirmed the

significant relationship of selected visual skills to different levels of learning. Interpretations

and explanations for the obtained results were presented. Trends in research into vision and

visual processes were discussed. Applications for study results to education and instructional

design were reviewed and potential areas for future research were suggested. The importance

of selected visual skills in academic achievement under the limitations specified within the

study was confirmed. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record

222 of 887 in PsycINFO 1998



Kluge, T., U. Fickel, et al. (2000). “Influence of moving random-dot patterns on synchrony in cat

striate and extrastriate corte.” European Journal of Neuroscience 12: 128-128.



Kluge, T., U. Fickel, et al. (2000). “Synchronization induced by moving random-dot patterns in cat

striate and extrastriate cortex.” Journal of Cognitive Neuroscience: 36-36.



Knapp, A. G. and J. A. Anderson (1984). “Theory of categorization based on distributed memory

storage.” Journal of Experimental Psychology: Learning, Memory, and Cognition 10(4): 616-

637.

Conducted 2 experiments to test a model of categorization developed by the authors. The

distributed memory model is an alternative to probabilistic and exemplar models of

categorization, and it is based on the assumption of distributed memory storage. The model is

presented in the context of previously conducted studies using stimuli composed of random

dots. When the number of exemplars of the stimulus patterns is small, new dot patterns are

classified according to their similarity to learned exemplars; when the number is large,

accuracy depends on a dot pattern's similarity to a prototype pattern. In Exp I of this study (n =

10), perceived similarity was measured between 2 dot patterns, one a distortion of the other. In

Exp II (n = 21), groups of exemplar patterns derived from a category prototype were classified

together in a category-learning task. Results show that the model correctly predicted the

quantitative and qualitative findings of the 2 experiments. (42 ref) (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 689 of 887 in PsycINFO 1978-1984



Knight, R. A., M. Sherer, et al. (1978). “A picture integration task for measuring iconic memory in

schizophrenics.” Journal of Abnormal Psychology 87(8): 314-321.

Two previous studies by the 1st author et al (1977) and G. Sperling (1960) using different

techniques (partial report and backward masking) have found at least some subgroups of

schizophrenics deficient in iconic memory. Both hypothesized that the icon in some

schizophrenics might be either weakly formed, limited in capacity, or abnormal in duration,

but neither study was able to test the qualities of the icon independent of possible transfer

difficulties. The present study with 50 male 18-55 yr old psychiatric patients (35

schizophrenics and 15 nonpsychotics) developed a picture integration task that was analogous

to C. W. Eriksen and J. F. Collins's (1973) random dot integration. With this task, the capacity

and decay of the icon independent of transfer to short-term store was assessed. The icon itself

was found intact in all schizophrenics. Other explanations are suggested for schizophrenics'

inadequate partial report and backward masking performance. (25 ref) (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 807 of 887 in PsycINFO 1978-1984



Knill, D. C., D. Field, et al. (1990). “Human discrimination of fractal images.” Journal of the Optical

Society of America 7(6): 1113-1123.

Investigated which value of the exponent beta describes the power spectrum of the ensemble

of images to which the visual system is optimally tuned. Three Ss were asked to discriminate

randomly generated noise textures based on their spectral drop-off. Whereas the

discrimination-threshold function of an ideal observer was flat for different spectral drop-offs,

human observers showed a broad peak in sensitivity for 2.8 2 years and

80% of the children between ages 6 months and 2 years were able to perform the MDRS test

on at least one occasion. Sixty percent of the 6-month to 2-year-old children were able to

perform the Stereo Smile test on both occasions. Performance on the MDRS test improved

with age up to 9 years. Improvement on the Frisby and Randot tests was seen in children aged

up to 7 years. Mean and 95% confidence interval ranges for each test are given.Conclusion:

This study gives evidence that aspects of the visual system are not fully mature until age 7-9

years. The MDRS test is a visually demanding but cognitively simple test that shows potential

for detecting visual anomalies in young children.



Ledgeway, T. (1996). “How similar must the Fourier spectra of the frames of a random-dot

kinematogram be to support motion perception?” Vision Research 36(16): 2489-2495.

Direction-discrimination performance was measured for two-frame random-dot

kinematograms in which one or both frames were spatial frequency filtered with a one octave

band-pass filter and the centre frequency of this filter was varied in the range 0.75-9 c/deg

independently for each frame. When both frames were filtered so that they contained common

(overlapping) spatial frequencies direction discrimination was extremely good but it

deteriorated rapidly as the degree of spectral overlap between the two frames decreased. These

results are consistent with previous findings that suggest that the mechanisms that mediate the

initial stages of motion detection are narrowly tuned for spatial frequency and cannot combine

information conveyed at disparate frequencies in order to compute an unambiguous estimate

of the direction of local motion, However, when only one of the frames was band-pass filtered

and the other was unfiltered (broadband), the correct direction of stimulus motion could be

discriminated reliably for a broad range of filter centre frequencies. Performance was best

when the centre frequency of the filtered frame was at medium spatial frequencies and tended

to deteriorate as the centre frequency approached either extreme of the spatial frequency range

examined, This basic pattern of results may be attributed to the visual system's differential

sensitivity to the Fourier components present in the unfiltered frame. Copyright (C) 1996

Elsevier Science Ltd.



Ledgeway, T. (1999). “Discrimination of the speed and direction of global second-order motion in

stochastic displays.” Vision Research 39(22): 3710-3720.

The ability to integrate local second-order motion signals over space and time was examined

using random-dot-kinematograms (RDKs) in which the dots were defined by spatial variation

in the contrast, rather than luminance, of a random noise field. When either the speeds or the

directions of the individual dots were selected at random from a range of possible values,

globally the stimulus appeared to drift either in a single direction or at a single speed in a

manner analogous to that reported previously for first-order (luminance-defined) RDKs. To

quantify the precision with which observers could extract the global stimulus motion, speed-

and direction-discrimination thresholds were measured using pairs of RDKs, one of which (the

comparison) comprised dots whose speeds or directions were assigned stochastically and the

other (the standard) comprised dots that all had the same drift direction and speed. Speed-

discrimination thresholds were of the order of 8% and changed little as the range of dot speeds

(bandwidth) of the comparison increased, in that performance was almost as good when the

individual dot speeds were selected at random from a range spanning 3.84 deg/s as when all

the dots moved at the same speed. There was a tendency for the perceived global speed of the

comparison RDK to decrease as the speed bandwidth was increased and perceived speed

tended to coincide with the geometric mean speed of the dots rather than the arithmetic mean

speed. Direction-discrimination thresholds were lowest (similar to 4 degrees) when the range

of dot directions was less than 90 degrees but increased markedly thereafter. Observers were

able to perform both discrimination tasks when the lifetimes of the dots comprising the RDKs

was reduced from 25 to 2 frames, a manipulation that prevented observers from determining

the overall speed or direction of image motion from the extended trajectories of individual

dots within the display. Thresholds under these conditions were somewhat higher but were

otherwise comparable to those obtained with a dot lifetime of 25 frames. The similarities

between the present results and those of previous studies that have employed first-order RDKs

suggest that the extraction of the global speed and direction of each type of motion is likely to

be based on computationally similar principles. (C) 1999 Elsevier Science Ltd. All rights

reserved.



Ledgeway, T. and R. F. Hess (2002). “Failure of direction identification for briefly presented second-

order motion stimuli: evidence for weak direction selectivity of the mechanisms encoding

motion.” Vision Research 42(14): 1739-1758.

We sought to investigate why the direction of second-order motion, unlike first-order motion,

cannot be identified when the stimulus exposure duration is brief ( 200 gram-force at the end of a trial and was close to the visually defined

direction. When a constant bias force of 110 gram-force was applied in various directions in

blocks of trials, the force exerted by the subject increased in time, as above; however, its

direction also changed in time so that the instantaneous vector sum of the bias force and the

force exerted by the subject pointed close to the visually defined direction. The T(i) and the

reaction time (RT) did not differ significantly in the two experimental conditions. These

results suggest that the directional control of isometric forces is very efficient, especially in

relation to visuomotor coordination. (b) The T(i) was calculated at various levels of force

intensity, as the latter increased from approximately 50 gram-force to 200 gram-force. There

was a gain of information with force intensity for all experimental conditions studied (i.e.

stereoscopic depth, absence of visual force feedback, and presence of force bias). This

suggests that the specification of the direction of force improves as the force intensity

increases, which could be due to a continuous comparison and correction of the force

produced so that it is in the visually defined direction. The curves of T(i) vs. force intensity, F,

were negatively accelerating. The relation between T(i) and F was a power function of the

form:[GRAPHICS]where k and m are constant. Equation (1) is linear in a log-log

scale:[GRAPHICS] where A = 1n-kappa. The constant m was similar but the constant A lower

in various experimental conditions in which stimulus conditions were manipulated (e.g.

absence of visual force feedback). In contrast, the presence of constant force bias did not

affect the values of m or A. These findings indicate that the rate of gain of information (that is,

the slope m in the second equation above) is very similar in different cases but that the curve

is displaced to lower levels of T(i) by the degradation of visual definition of the instructed

force direction. Finally, application of external force bias affects neither the rate nor the

amount of information gained.



Massey, J. T., R. A. Drake, et al. (1991). “Cognitive Spatial-Motor Processes .4. Specification of the

Direction of Visually Guided Isometric Forces in 2-Dimensional Space - Information

Transmitted and Effects of Visual Force-Feedback.” Experimental Brain Research 83(2): 439-

445.

The information transmitted (T(i)) by the direction of two-dimensional (2-D) isometric forces

at different stereoscopic depths was studied in 50 naive human subjects using an isometric

manipulandum and random dot stereograms generated in a color display (Massey et al. 1988).

Subjects viewed the display through appropriate color filters and perceived the image of a disk

rotated about a horizontal axis on the frontal plane; the top of the disk was rotated around that

axis by 15, 45, 60 and 80-degrees away from the subject. Each of these disks involved a

different amount of stereoscopic depth perception which was lowest for the 15-degrees and

highest for the 80-degrees tilt. Subjects were instructed to exert force in the direction of a

visual target presented on the disk in a reaction time task. The instantaneous force exerted by

the subjects on the manipulandum was shown on the disk in the form of a feedback cursor.

Information transmitted, reaction time (RT) and systematic directional deviations were

calculated. We found the following. (a) T(i) increased with input information but at a lower

rate; at the highest level of input information studied (5.91 bits), T(i) was 4.1 bits at the 15-

degrees tilt. This high value of T(i) suggests that directional information for isometric force is

processed very efficiently. However, this T(i) was consistently lower than that transmitted by

the direction of movement (Georgopoulos and Massey, 1988). (b) T(i) did not differ

significantly among the 15-60-degrees tilts but was 0.19 bits less for the 80-degrees tilt. RT

did not differ among the 15-80-degrees tilts. (c) There was a small but systematic clustering of

force directions along the diagonal directions (i.e., away from the major axes). This clustering

decreased by changing the configuration of the arm relative to the manipulandum. (d) A

significant decrease of T(i) (by 0.29 bits, on the average) and an increase of RT (by 80 ms, on

the average) were observed when the force-feedback cursor was turned off at the beginning of

the RT. These findings suggest that the visual definition of the origin of the upcoming force

vector is important for the generation of force in the appropriate direction.



Masson, G. S., C. Busettini, et al. (1997). “Vergence eye movements in response to binocular disparity

without depth perception.” Nature 389(6648): 283-286.

Primates use vergence eye movements to align their two eyes on the same object and can

correct misalignments by sensing the difference in the positions of the two retinal images of

the object (binocular disparity). When large random-dot patterns are viewed dichoptically and

small binocular misalignments are suddenly imposed (disparity steps), corrective vergence eye

movements are elicited at ultrashort latencies(1,2). Here we show that the same steps applied

to dense anticorrelated patterns, in which each black dot in one eye is matched to a white dot

in the other eye, initiate vergence responses that are very similar, except that they are in the

opposite direction. This sensitivity to the disparity of anticorrelated patterns is shared by many

disparity-selective neurons in cortical area V1 (ref. 3), despite the fact that human subjects fail

to perceive depth in such stimuli(4,5). These data indicate that the vergence eye movements

initiated at ultrashort latencies result solely from locally matched binocular features, and

derive their visual input from an early stage of cortical processing before the level at which

depth percepts are elaborated.



Masson, G. S., C. Busettini, et al. (2001). “Short-latency ocular following in humans: sensitivity to

binocular disparity.” Vision Research 41(25-26): 3371-3387.

We show that the initial ocular following responses elicited by motion of a large pattern are

modestly attenuated when that pattern is shifted out of the plane of fixation by altering its

binocular disparity. If the motion is applied to only restricted regions of the pattern, however,

then altering the disparity of those regions severely attenuates their ability to generate ocular

following. This sensitivity of the ocular tracking mechanism to local binocular disparity would

help the observer who moves through a cluttered 3-D world to stabilize objects in the plane of

fixation and ignore all others. (C) 2001 Elsevier Science Ltd. All rights reserved.



Masson, G. S., D. R. Mestre, et al. (1999). “Speed tuning of motion segmentation and discrimination.”

Vision Research 39(26): 4297-4308.

Motion transparency requires that the visual system distinguish different motion Vectors and

selectively integrate similar motion vectors over space into the perception of multiple surfaces

moving through or over each other. Using large-field (7 degrees x 7 degrees) displays

containing two populations of random-dots moving in the same (horizontal) direction but at

different speeds, we examined speed-based segmentation by measuring the speed difference

above which observers can perceive two moving surfaces. We systematically investigated this

'speed-segmentation' threshold as a function of speed and stimulus duration, and found that it

increases sharply for speeds above approximate to 8 degrees/s. In addition, speed-

segmentation thresholds decrease with stimulus duration out to approximate to 200 ms. In

contrast, under matched conditions, speed-discrimination thresholds stay low at least out to 16

degrees/s and decrease with increasing stimulus duration at a faster rate than for speed

segmentation. Thus, motion segmentation and motion discrimination exhibit different speed

selectivity and different temporal integration characteristics. Results are discussed in terms of

the speed preferences of different neuronal populations within the primate visual cortex. (C)

1999 Elsevier Science Ltd. All rights reserved.



Masson, G. S., D. S. Yang, et al. (2002). “Reversed short-latency ocular following.” Vision Research

42(17): 2081-2087.

Using the scleral search coil technique to monitor eye movements, we recorded short-latency

ocular following responses to displacement steps of large random-dot patterns. On half of the

trials, the luminance of the dots and background were reversed during the step, a procedure

that is known to reverse the direction of the perceived motion ("reverse phi"). Steps without

luminance reversal induced small but consistent ocular following in the direction of the steps

at ultra-short latency (

almost-equal-to 30% of available space. The estimates derived from the other techniques were

generally not significantly different from each other for percent coverage of this magnitude.

The methods were not significantly different in their abilities to estimate percent cover of less

abundant species although each of the dot methods frequently failed to detect species covering

out task. Of 514

cells analyzed for both the motor and visual tasks, 388 (75.5%) showed a significant relation

to either or both tasks, as follows: 284/388 (73.2%) cells showed a significant relation only to

the motor task, 27/388 (7%) cells showed a significant relation only to the visual task, whereas

the remaining 77/388 (19.8%) cells showed significant relations to both tasks. Therefore a

total of 361/514 (70.2%) cells were related to the motor task and 104/51 (20.2%) were related

to the visual task. Finally, with respect to receptive fields (RFs), there was no clear visual

receptive field structure in the motor cortical neuronal responses, in contrast to area 7a where

RFs were present and could be modulated by the type of optic flow stimulus.



Merchant, H., A. Battaglia-Mayer, et al. (2003). “Functional organization of parietal neuronal

responses to optic-flow stimuli.” Journal of Neurophysiology 90(2): 675-682.

We analyzed the dissimilarity matrix of neuronal responses to moving visual stimuli using tree

clustering and multidimensional scaling (MDS). Single-cell activity was recorded in area 7a

while random dots moving coherently in eight different kinds of motion (right-, left-, up-, and

downward, clockwise, counterclockwise, expansion, contraction) were presented to behaving

monkeys with eyes fixated. Tree clustering analyses showed that the {rightward, leftward},

{upward, downward}, and {clockwise, counterclockwise]} motions were clustered in three

separate branches (i.e., horizontal, vertical, and rotatory motion, respectively). In contrast,

expansion was in a lone branch, whereas contraction was also separate but within a larger

cluster. The distances among these clusters were then subjected to an MDS analysis to identify

the dimensions underlying the tree clustering observed. This analysis revealed two major

factors in operation. The first factor separated expansion from all other stimulus motions,

which seems to reflect the prominence of expansion during the common activity of

locomotion. In contrast, the second factor separated planar motions from motion in depth,

which suggests that the latter may hold a special place in visual motion processing.



Mestre, D. R. and G. S. Masson (1997). “Ocular responses to motion parallax stimuli: The role of

perceptual and attentional factors.” Vision Research 37(12): 1627-1641.

When human subjects are presented with visual displays consisting of random dots moving

sideways at different velocities, they perceive transparent surfaces, moving in the same

direction but located at different distances from themselves. They perceive depth from motion

parallax, without any additional cues to depth, such as relative size, occlusion or binocular

disparity. Simultaneously, large-field visual motion triggers compensatory eye movements

which tend to offset such motion, in order to stabilize the visual image of the environment. In

a series of experiments, we investigated how such reflexive eye movements are controlled by

motion parallax displays, that is, in a situation where a complete stabilization of the visual

image is never possible, Results show that optokinetic ngstagmus, and not merely active

visual pursuit of singular elements, is triggered by such displays. Prior to the detection of

depth from motion parallax, eye tracking velocity is equal to the average velocity of the visual

image. After detection, eye tracking velocity spontaneously matches the slowest velocity in

the visual field, but can be controlled by attentional factors, Finally, for a visual stimulation

containing more than three velocities, subjects are no longer able to perceptually dissociate

between different surfaces in depth, and eye tracking velocity remains equal to the average

velocity of the visual image. These data suggest that, in the presence of flow fields containing

motion parallax, optokinetic eye movements are modulated by perceptual and attentional

factors. (C) 1997 Elsevier Science Ltd.



Mestre, D. R., G. S. Masson, et al. (2001). “Spatial scale of motion segmentation from speed cues.”

Vision Research 41(21): 2697-2713.

For the accurate perception of multiple, potentially overlapping, surfaces or objects, the visual

system must distinguish different local motion vectors and selectively integrate similar motion

vectors over space to segment the retinal image properly. We recently showed that large

differences in speed are required to yield a percept of motion transparency. In the present

study. to investigate the spatial scale of motion segmentation from speed cues alone, we

measured the speed-segmentation threshold (the minimum speed difference required for 75%

performance accuracy) for 'corrugated' random-dot patterns, i.e. patterns in which dots with

two different speeds were alternately placed in adjacent bars of variable width. In a first

experiment, we found that, at large bar widths, a smaller speed difference was required to

segment and perceive the corrugated pattern of moving dots, while at small bar-widths, a

larger speed difference was required to segment the two speeds and perceive two transparent

surfaces of moving dots. Both the perceptual and segmentation performance transitions

occurred at a bar width of around 0.4 degrees. In a second experiment, speed-segmentation

thresholds were found to increase sharply when dots with different speeds were paired within

a local pooling area. The critical pairing distance was about 0.2 degrees in the fovea and

increased linearly with stimulus eccentricity. However, across the range of eccentricities tested

(up to 15 degrees), the critical pairing distance did not change much and remained close to the

receptive field size of neurons within the primate primary visual cortex. In a third experiment,

increasing dot density changed the relationship between speed-segmentation thresholds and

bar width. Thresholds decreased for large bar widths, but increased for small bar widths. All

of these results are well fit by a simple stochastic model, which estimates the probabilities of

having identical or different motion vectors within a local pooling area whose size is the same

as that of primate V1 neurons. Altogether, these results demonstrate that speed-based

segmentation can function well, even at small spatial scales (i.e. high-spatial frequencies of

spatial corrugation) and thereby emphasizes the critical role of a local pooling process early in

the cortical motion-processing pathway. (C) 2001 Elsevier Science Ltd. All rights reserved.



Metcalfe, J. and R. P. Fisher (1986). “The relation between recognition memory and classification

learning.” Memory and Cognition 14(2): 164-173.

Two experiments investigated the relation between recognition memory and classification

learning. 311 undergraduates were instructed that they would see a series of random-dot

patterns and later would be asked to classify or to recognize the patterns. Ss then performed a

classification task, a recognition-memory task, or both. Classification-learning instructions

were superior to recognition-memory instructions for the classification task, but there was

little or no effect of instructions on the recognition task. When Ss performed both recognition

and classification tasks, there was no relation between recognizing a probe and correctly

classifying it, except with old exemplars. Data show that classification and recognition can be

experimentally separated. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 648 of 887 in PsycINFO 1985-1987



Michel, C. M., B. Henggeler, et al. (1992). “42-Channel Potential Map Series to Visual Contrast and

Stereo Stimuli - Perceptual and Cognitive Event-Related Segments.” International Journal of

Psychophysiology 12(2): 133-145.

Event-related potential maps to perceptual (stimulus type) and cognitive (stimulus relevance)

manipulations were studied in 12 healthy volunteers using 42-channel mapping. Perceptual

manipulation used three types of visual stimuli: rectangles constituted by: (1) contrast; (2)

different densities of monocular Dynamic Random Dots (Flat DRD); and (3) different

binocular disparities of Dynamic Random Dots (Stereo DRD). Cognitive manipulation within

each stimulus type consisted of presenting the rectangles horizontally and vertically, one of

the two with a probability of 33%, and requesting the subjects to count and thus attend to the

'rare' rectangles. Spatial characteristics of the maps were analyzed; this allowed conclusions

about the generating sources. The map series were adaptively segmented using the minima

points of the grand mean Global Field Power curve. Segment strength (Global Field Power)

and segment landscape (locations of extreme potentials) were assessed. Stimulus type had

effects from 78 to 310 ms, stimulus relevance was effective from 210 to 1000 ms. In the 78-

174 ms segment, Stereo DRD and Flat DRD stimuli produced similar map landscapes, while

contrast stimuli produced different map landscapes. Attended and ignored stimuli produced

contrary effects on landscapes at 210-310 ms as compared to those at 310-546 ms, indicative

of different neural populations activated by attention processes during these late event-related

potential segments. Interaction between perceptual and cognitive manipulation occurred at

210-310 ms when perceiving stereo stimuli and attending to relevant monocular visible stimuli

produced similar map landscapes, suggesting a common brain resource during this segment

for automatic figure perception and voluntary attention. The observed functional differences

of the segments contribute to the identification of global functional microstates of brain

electric activity.



Michel, C. M., B. Henggeler, et al. (1992). “42-Channel potential map series to visual contrast and

stereo stimuli: Perceptual and cognitive event-related segments.” International Journal of

Psychophysiology 12(2): 133-145.

Event-related potential maps to perceptual (stimulus type) and cognitive (stimulus relevance)

manipulations were studied in 12 21-34 yr old healthy volunteers using 42-channel mapping.

Perceptual manipulation included rectangles constituted by (1) contrast, (2) different densities

of monocular dynamic random dots (flat DRD), and (3) different binocular disparities of DRD

(stereo DRD). Cognitive manipulation consisted of presenting the rectangles horizontally and

vertically, 1 of the 2 with a probability of 33%, and requesting the Ss to count. Interaction

between perceptual and cognitive manipulation occurred at 210-310 msec when perceiving

stereo stimuli and attending to relevant monocular visible stimuli produced similar map

landscapes. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 511 of

887 in PsycINFO 1990-1992



Miezin, F. M., J. Myerson, et al. (1981). “Evoked potentials to dynamic random-dot correlograms in

monkey and man: A test for cyclopean perception.” Vision Research 21(2): 177-179.

Dynamic random-dot correlograms elicited cortical evoked potentials in a juvenile female

Macaca fasicularis monkey and human Ss. Control conditions that disturbed the binocular

correlation eliminated or diminished the evoked potentials. Thus, the evoked potentials were a

response to the uniquely binocular (i.e., cyclopean) aspects of the stimulus. The procedure

used in this experiment allows a fast, objective assessment of cyclopean perception. (9 ref)

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 768 of 887 in

PsycINFO 1978-1984



Miezin, F. M., J. Myerson, et al. (1981). “Evoked-Potentials to Dynamic Random-Dot Correlograms in

Monkey and Man - a Test for Cyclopean Perception.” Vision Research 21(2): 177-179.



Mikami, A. (1991). “Direction selective neurons respond to short-range and long-range apparent

motion stimuli in macaque visual area MT.” International Journal of Neuroscience 61(1-2):

101-112.

Tested the involvement of 2 awake monkeys' visual middle temporal (MT) area with short-

and long-range processes of apparent motion, using random dot and slit stimuli. Most

direction selective MT neurons showed direction selective responses to both the alternating

slit (ASL) and the alternating random dots (ARDs), suggesting that MT is involved in the

processing of the smooth motion and sequentially presented stroboscopic stimuli and also in

the processing of apparent motion induced by alternating stimuli. The maximum spatial

separation that supported directional response in each neuron was smaller for the ARDs than

the ASL. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 525 of 887

in PsycINFO 1990-1992



Miles, F. A. (1998). “The neural processing of 3-D visual information: evidence from eye movements.”

European Journal of Neuroscience 10(3): 811-822.

Primates have several reflexes that generate eye movements to compensate for bodily

movements that would otherwise disturb their gaze and undermine their ability to process

visual information. Two vestibule-ocular reflexes compensate selectively for rotational and

translational disturbances of the head, and each has visual backups that operate as negative

feedback tracking mechanisms to deal with any residual disturbances of gaze. Of particular

interest here are three recently discovered visual tracking mechanisms that specifically address

translational disturbances and operate in machine-like fashion with ultra-short latencies (80%) in MT in a task that shares many features with

ours. Our results suggest that spatial attention alone is not sufficient to induce strong

attentional effects in MT even when two competing motion stimuli appear within the RF of

the recorded neuron. The difference between our results and those of Treue and Maunsell

suggests that the magnitude of the attentional effects in MT may depend critically on how

attention is directed to a particular stimulus and on the precise demands of the task.



Sekuler, A. B., R. Sekuler, et al. (1996). “Perceived direction of motion vs detection of global flow in

random dot cinematograms.” Investigative Ophthalmology & Visual Science 37(3): 2363-

2363.



Sekuler, R. W. (1980). “Random-Dot Arrays in Movement Perception.” Journal of the Optical Society

of America 70(12): 1584-1584.



Sereno, M. E. and M. I. Sereno (1999). “2-D center-surround effects on 3-D structure-from-motion.”

Journal of Experimental Psychology-Human Perception and Performance 25(6): 1834-1854.

This study investigates how mechanisms for amplifying 2-D motion contrast influence the

assignment of 3-D depth values, The authors found that the direction of movement of a

random-dot, conveyor belt strongly inclined observers to report that the front surface of a

superimposed, transparent, rotating, random-dot sphere moved in a direction opposite to the

belt. This motion-contrast effect was direction selective and demonstrated substantial spatial

integration. Varying the stereo depth of the belt did not compromise the main effect,

precluding a mechanical interpretation (sphere rolling on belt). Varying the speed of the

surfaces of the sphere also did nor greatly affect the interpretation of rotation direction. These

results suggest that 2-D center-surround interactions influence 3-D depth assignment by

differentially modulating the strength of response to the moving surfaces of an object (their

prominence) without affecting featural specificity.



Sereno, M. E., T. Trinath, et al. (2002). “Three-dimensional shape representation in monkey cortex.”

Neuron 33(4): 635-652.

Using fMRI in anesthetized monkeys, this study investigates how the primate visual system

constructs representations of three-dimensional (3D) shape from a variety of cues. Computer-

generated 3D objects defined by shading, random dots, texture elements, or silhouettes were

presented either statically or dynamically (rotating). Results suggest that 3D shape

representations are highly localized, although widely distributed, in occipital, temporal,

parietal, and frontal cortices and may involve common brain regions regardless of shape cue.

This distributed network of areas cuts across both "what" and "where" processing streams,

reflecting multiple uses for 3D shape representation in perception, recognition, and action.



Seu, L. and V. P. Ferrera (2001). “Detection thresholds for spiral Glass patterns.” Vision Research 41:

3785-3790.

The authors measured thresholds for the detection of spiral Glass patterns in the presence of

random noise. Nine Ss (aged 16-40 yrs) participated in the experiment. The patterns were

constructed so that the orientation content did not vary as a function of spiral angle or signal

level. Spiral patterns had higher thresholds than either radial or concentric Glass patterns. The

results support the idea that the human visual system is specialized to detect radial and

concentric patterns.



Shadlen, M. N. and W. T. Newsome (2001). “Neural basis of a perceptual decision in the parietal

cortex (area LIP) of the rhesus monkey.” Journal of Neurophysiology 86(4): 1916-1936.

We recorded the activity of single neurons in the posterior parietal cortex (area LIP) of two

rhesus monkeys while they discriminated the direction of motion in random-dot visual stimuli.

The visual task was similar to a motion discrimination task that has been used in previous

investigations of motion-sensitive regions of the extrastriate cortex. The monkeys were trained

to decide whether the direction of motion was toward one of two choice targets that appeared

on either side of the random-dot stimulus. At the end of the trial, the monkeys reported their

direction judgment by making an eye movement to the appropriate target. We studied neurons

in LIP that exhibited spatially selective persistent activity during delayed saccadic eye

movement tasks. These neurons are thought to carry high-level signals appropriate for

identifying salient visual targets and for guiding saccadic eye movements. We arranged the

motion discrimination task so that one of the choice targets was in the LIP neuron's response

field (RF) while the other target was positioned well away from the RE During motion

viewing, neurons in LIP altered their firing rate in a manner that predicted the saccadic eye

movement that the monkey would make at the end of the trial. The activity thus predicted the

monkey's judgment of motion direction. This predictive activity began early in the motion-

viewing period and became increasingly reliable as the monkey viewed the random-dot

motion. The neural activity predicted the monkey's direction judgment on both easy and

difficult trials (strong and weak motion), whether or not the judgment was correct. In addition,

the timing and magnitude of the response was affected by the strength of the motion signal in

the stimulus. When the direction of motion was toward the RF, stronger motion led to larger

neural responses earlier in the motion-viewing period. When motion was away from the RF,

stronger motion led to greater suppression of ongoing activity. Thus the activity of single

neurons in area LIP reflects both the direction of an impending gaze shift and the quality of

the sensory information that instructs such a response. The time course of the neural response

suggests that LIP accumulates sensory signals relevant to the selection of a target for an eye

movement.



Shao, Y. and J. E. W. Mayhew (1998). “PLiNC algorithm: pattern location in noisy contexts.” Iee

Proceedings-Vision Image and Signal Processing 145(2): 109-115.

The problem that is addressed can be likened to that of detecting the position of a random dot

leopard continually and incoherently changing its spots against a continually and also

incoherently changing similar (but not stochastically identical) spotted background. An

algorithm has been developed, which can locate near-rigid targets consisting of spatially

separated patches presented against a background of very similar texture. The patches and

background are drawn from different distributions, and renewed at every time step. The

algorithm works by efficiently integrating weak measurement information over time,

converging rapidly to a hypothesis and associated probability. The measurements and

associated 'uncertainties' are obtained using the Forstner corner and circular feature algorithm.

The results of the algorithm appear superior to the human ability to detect these sort of targets

in noise textures. The mathematics elaborating some formal constraints on the performance of

the algorithm is presented.



Shedden, J. M. and C. L. Nordgaard (2001). “ERP time course of perceptual and post-perceptual

mechanisms of spatial selection.” Cognitive Brain Research 11(1): 59-75.

Event-related potentials (ERPs) were recorded from volunteers performing a task requiring

simple judgements about the spatial location of a single target that could appear with equal

probability to the left or right of fixation. A robust finding in the ERP literature is a dichotomy

between attentional selection for spatial and non-spatial features. Visual spatial selection is

manifest as a modulation of early components (P1, N1) that reveal exogenous processes, while

non-spatial selection is revealed by the presence of longer latency endogenous components

(N2). We present an analysis of several conditions that require different degrees of visual

analysis to confirm the location of the single target, and show that spatial selection can be

manifest at early (N1) or later (N2) stages. Observers identified the location of targets that

were more salient (2D line drawings with abrupt onset) or less salient (2D line drawings

without abrupt onset or 3D objects embedded in random-dot stereograms). We examined

differences in amplitude, latency, and topography of early ERP components (P1, N1, P2, N2),

and compared responses measured over the left and right hemispheres in response to left and

right targets. The results support the hypothesis that the processes involved in spatial selection

can be manifest at early or late stages, dependent on the quality of the incoming data.

Moreover., the iterative process by which the percept is established benefits from a change in

the visual input that is specific to the target. (C) 2001 Elsevier Science B.V. All rights

reserved.



Sheppard, D. M., J. L. Bradshaw, et al. (2002). “Abnormal line bisection judgements in children with

Tourette's syndrome.” Neuropsychologia 40(3): 253-259.

Tourette's syndrome (TS) has been associated with loss of normal basal ganglia asymmetry, as

well as loss of normal functional asymmetry, including the leftward bias on traditional

visuospatial tasks such as line bisection and turning bias tests. The aim of the present study

was to examine the lateralisation of visuospatial attention in TS. We examined the effect of an

irrelevant moving-dot background on line bisection judgements. Nine children with a DSM IV

diagnosis of TS participated, in addition to 9 healthy controls, individually matched for age,

sex and IQ. Horizontal lines of varying length were presented on a computer screen with

either a blank background, or a moving, random-dot field. The dots moved either leftward or

rightward across the screen at 40 or 80 mm/s, and participants were instructed to ignore these

distracting stimuli when judging the lines. TS children were found to be abnormally right-

biased in line bisection in a similar fashion to unmedicated ADHD children who, in a previous

study, showed a similar small, yet significant, right-bias in line bisection. Matched controls

showed a small, nonsignificant left bias, consistent with past research. Unlike previous

findings with hemineglect patients, the irrelevant moving background had no effect on

bisection performance for TS children or healthy controls. The present findings suggest a

deficit in visuospatial attention consistent with the emerging picture of a lateralised

dysfunction of frontostriatal circuitry in TS. (C) 2001 Elsevier Science Ltd. All rights

reserved.



Sheppard, D. M., J. L. Bradshaw, et al. (1999). “Effects of stimulant medication on the lateralisation of

line bisection judgements of children with attention deficit hyperactivity disorder.” Journal of

Neurology Neurosurgery and Psychiatry 66(1): 57-63.

Objectives-Deficits in the maintenance of attention may underlie problems in attention deficit

hyperactivity disorder (ADHD). Children with ADHD also show asymmetric attention deficits

in traditional lateralisation and visuospatial orienting tasks, suggesting right hemispheric (and

left hemispace) attentional disturbance. This study aimed to examine the lateralisation of

selective attention in ADHD; specifically, the effect of a moving, random dot background, and

stimulant medication in the Line bisection task.Methods-The performance of children with

ADHD, on and off methylphenidate, was examined using a computerised horizontal Line

bisection task with moving and blank backgrounds. Twenty children with a DSM-IV

diagnosis of ADHD participated with 20 controls, individually matched for age, sex, grade at

school, and IQ. Twelve of the 20 children with ADHD were on stimulant medication at the

time of testing. Horizontal Lines of varying length were presented in the centre of a computer

screen, with either a blank background, or a moving, random dot field. The random dots

moved either leftward or rightward across the screen at either 40 mm/s or 80 mm/s.Results-

The children with ADHD off medication bisected lines significantly further to the right

compared with controls, who showed a small leftward error. Methylphenidate normalised the

performance of the children with ADHD for the task with the moving dots.Conclusions-These

results support previous evidence for a right hemispheric hypoarousal theory of attentional

dysfunction, and are consistent with the emerging picture of a lateralised dysfunction of

frontostriatal circuitry in ADHD.



Sheppard, D. M., J. L. Bradshaw, et al. (1999). “Effects of stimulant medication on the lateralisation of

line bisection judgements of children with attention deficit hyperactivity disorder.” Journal of

Neurology, Neurosurgery and Psychiatry 66(1): 57-63.

Examined the lateralization of selective attention in attention deficit hyperactivity disorder

(ADHD); specifically, the effect of a moving, random dot background, and stimulant

medication in the line bisection task. The performance of 20 children (aged 8.8-12.8 yrs) with

ADHD, on and off methylphenidate, and 20 controls was examined using a computerized

horizontal line bisection task with moving and blank backgrounds. Results show that the

children with ADHD off medication bisected lines significantly further to the right vs controls,

who showed a small leftward error. Methylphenidate normalized the performance of the

children with ADHD for the task with the moving dots. These results support previous

evidence for a right hemispheric hypoarousal theory of attentional dysfunction, and are

consistent with the emerging picture of a lateralized dysfunction of frontostriatal circuitry in

ADHD. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 175 of 887 in

PsycINFO 1999



Shibata, M., S. S. Stoyanov, et al. (1999). “Selective growth of nanometer-scale Ga dots on Si(111)

surface windows formed in an ultrathin SiO2 film.” Physical Review B 59(15): 10289-10295.

Selective growth of nanometer-scale Ga dots on patterned ultrathin SiO2 films was studied by

using scanning-reflection electron microscopy and energy-dispersive x-ray spectroscopy

(EDX). Nanometer-scale Si(111) surface windows were fabricated by electron-beam-induced

thermal decomposition of the film. Ga was deposited on the patterned surfaces at room

temperature to 550 degrees C. Under certain deposition and annealing conditions, Ga dots

were present only on the Si(111) surface windows, and the smallest size of the dots was about

20 nm. To understand the selective growth of Ga dots, we measured the desorption rate and

the surface-diffusion length of Ga atoms until all atoms desorbed from the SiO2 surface and

nucleated forming random dots. The EDX measurement showed that the desorption rate from

Ga dots on SiO2 films was 2 to 2.5 times larger than that on Si(111) surfaces, and that the

activation energy of desorption rate from SiO2 films was 1.33 eV. The Ga surface-diffusion

length was estimated by measuring the temperature dependence of the Ga depleted zone width

near the linear Si surface windows. The surface-diffusion length of Ga atoms on ultrathin

SiO2 films increased when the substrate temperature was increased. Thus, we were able to

selectively grow Ga dots on only the Si(111) surface windows. [S0163-1829(99)02716-2].



Shiffrar, M., X. Li, et al. (1995). “Motion integration across differing image features.” Vision Research

35(15): 2137-2146.

Four experiments examined how human observers interpret images containing motion signals

of differing degrees of ambiguity. Ss judged the perceived coherence of images consisting of

an ambiguously translating grating and an unambiguously translating random dot pattern.

Perceived coherence of the dotted grating depended upon the degree of concurrence between

the velocities of the grating terminators and dots. Depth relationships also played a critical role

in the motion integration process. When terminators were suppressed with occlusion cues,

coherence increased. When dots and gratings were presented at different depth planes,

coherence decreased. Results are used to outline the conditions under which the visual system

uses unambiguous motion signals to interpret object motion. (PsycINFO Database Record (c)

2002 APA, all rights reserved) Record 370 of 887 in PsycINFO 1993-1995



Shiffrar, M., X. J. Li, et al. (1995). “Motion Integration across Differing Image Features.” Vision

Research 35(15): 2137-2146.

To interpret the projected image of a moving object, the visual system must integrate motion

signals across different image regions. Traditionally, researchers have examined this process

by focusing on the integration of equally ambiguous motion signals. However, when the

motions of complex, multi-featured images are measured through spatially limited receptive

fields, the resulting motion measurements have varying degrees of ambiguity. In a series of

experiments, we examine how human observers interpret images containing motion signals of

differing degrees of ambiguity. Subjects judged the perceived coherence of images consisting

of an ambiguously translating grating and an unambiguously translating random dot pattern.

Perceived coherence of the dotted grating depended upon the degree of concurrence between

the velocities of the grating terminators and dots. Depth relationships also played a critical role

in the motion integration process, When terminators were suppressed with occlusion cues,

coherence increased. When dots and gratings were presented at different depth planes,

coherence decreased. We use these results to outline the conditions under which the visual

system uses unambiguous motion signals to interpret object motion.



Shimojo, S. and Y. Nakajima (1981). “Adaptation to the reversal of binocular depth cues: Effects of

wearing left-right reversing spectacles on stereoscopic depth perception.” Perception 10(4):

391-402.

The principle of stereopsis, that crossed disparity causes a convex perception and uncrossed

disparity a concave one, has long been considered to depend on a very rigid neural mechanism

not affected by experience. A series of experiments with 1 S are reported which show that this

relationship between disparity and perceived depth can be reversed by experience. S wore a

pair of left-right reversing spectacles continuously for 9 days. The spectacles also reversed the

relationship between the direction of perceived depth and the direction of binocular depth cues

(i.e., disparity and vergence). Beginning 2 days before wearing the spectacles and continuing

until 79 days after removing them, S was examined with a haploscope and an

electrooculograph. All the stereoscopic experiments were carried out without spectacles to

examine some aftereffects of wearing spectacles. For the stereograms with linear contours, not

only the adaptive reversal of the relationship between disparity and perceived depth was found

but also some abnormal depth perceptions and long-lasting aftereffects. For B. Julesz's (1971)

random-dot stereograms, however, in which contours can be seen only after binocular

combination, no adaptive change or reversal occurred. (29 ref) (PsycINFO Database Record

(c) 2002 APA, all rights reserved) Record 744 of 887 in PsycINFO 1978-1984



Shimojo, S. and K. Nakayama (1994). “Interocularly unpaired zones escape local binocular matching.”

Vision Research 34(14): 1875-1881.

When a closer surface partially occludes a more distant surface, there exist image zones

adjacent to the occluding edge on the rear surface that are only visible to one eye. These

interocularly unpaired zones do not carry explicit disparity information, yet their depth is

perceived as a stable and continuous extension of the rear surface. In the present experiment,

the authors tested whether the local correspondence process functions differently in paired vs

unpaired zones. Exp 1 tested depth rating of an unpaired probe added to a random-dot

stereogram in 2 naive and 2 non-naive observers; Exp 2 tested disparity matching of an

unpaired probe in 1 observer. The added unpaired probe dot escaped nonunique local Panum

matching that would otherwise have bestowed it with a depth outside the surface. Depth of the

probe was most stable in the unpaired zone. (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 433 of 887 in PsycINFO 1993-1995



Shimono, K. and H. Ono (1990). “Perceived depth produced by luminance differences in the two eyes

with zero disparity.” Japanese Journal of Psychology 61(4): 263-267.

Studied the finding that perceived depth covaries with relative luminance of the 2 half-fields

of the stereogram (L. Kaufman et al, 1973). Human subjects: Five normal male and female

Japanese adults (aged 21-36 yrs). Ss were shown 2 sets of stereograms--1 with 3 lines, and 1

with random dots. In each trial, Ss reported the apparent depth plane produced by 1 of 15

different relative luminances of the lines or midportions of the random dots. (English abstract)

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 535 of 887 in

PsycINFO 1990-1992



Shimono, K., H. Ono, et al. (1998). “Methodological caveats for monitoring binocular eye position

with nonius stimuli.” Vision Research 38(4): 591-600.

Three experiments, using two sets of Nonius lines placed in a random-dot stereogram,

indicated that Nonius alignment does not always reflect binocular eye position and, thus, a

caveat is necessary when Nonius alignment is used to monitor binocular eye position. We

found that: (a) two Nonius lines with visual line values that differed by up to 7.6 min of are

can appear aligned; (b) the two lines of each of the two Nonius sets continued to appear

aligned despite a change in vergence angle of 5.9 min of are; and (c) the Nonius alignment

reflected eye position better, when the binocular dots near the Nonius lines were eliminated.

(C) 1998 Elsevier Science Ltd. All rights reserved.



Shimono, K. and N. J. Wade (2002). “Monocular alignment in different depth planes.” Vision Research

42(9): 1127-1135.

We examined (a) whether vertical lilies at different physical horizontal positions in the same

eye can appear to be aligned, and (b), if so, whether the difference between the horizontal

positions of the aligned vertical lines can vary with the perceived depth between them. In two

experiments, each of two vertical monocular lines was presented (in its respective rectangular

area) in one field of a random-dot stereopair with binocular disparity. In Experiment 1, 15

observers were asked to align a line in all upper area with a line in a lower area. The results

indicated that when the lilies appeared aligned, their horizontal physical positions could differ

and the direction of the difference coincided with the type of disparity of the rectangular areas;

this is not consistent with the law of the Visual direction of monocular stimuli. In Experiment

2, 11 observers were asked to report relative depth between the two lilies and to align them.

The results indicated that the difference of the horizontal position did not covary with their

perceived relative depth, suggesting that the visual direction and perceived depth of the

Monocular line are mediated via different mechanisms. (C) 2002 Elsevier Science Ltd. All

rights reserved.



Shioiri, S. and P. Cavanagh (1989). “Saccadic suppression of low-level motion.” Vision Research

29(8): 915-928.

Isolated motion mechanisms to study the influence of saccades on motion perception in the

absence of other cues for detecting the displacement of images, such as the position of a target

relative to the surround or to the observer's head. The authors served as observers and could

not identify the direction of motion of random dots moved within a stationary frame, if the

displacement occurred during a saccade. This suppression also occurred when the

displacement of the random dots was less than D-sub(max ) in retinal coordinates and even

when the saccade was embedded in a slightly longer blank interstimulus interval. (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 595 of 887 in PsycINFO 1988-

1989



Shioiri, S. and P. Cavanagh (1990). “ISI produces reverse apparent motion.” Vision Research 30(5):

757-768.

In 3 experiments, a moving random-dot stimulus was presented in 2 sequential frames

separated by an interstimulus interval (ISI) during which the field was spatially uniform with

luminance equal to either the average luminance of the stimulus field (grey) or that of the

black dots (black). Findings suggest that there is a significant biphasic temporal response

function (TRF) that precedes the analysis of motion in the visual system. This indicates that

the overall TRF of the visual system is the result of a cascade of functions from early through

late stages and that only a portion of the overall TRF can be attributed to stages involved in

motion analysis. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 564

of 887 in PsycINFO 1990-1992



Shioiri, S. and P. Cavanagh (1992). “Visual Persistence of Figures Defined by Relative Motion.”

Vision Research 32(5): 943-951.

In order to measure visual persistence of figures that were solely defined by relative motion

(motion-defined figures or motion figures), random-dot kinematograms were used to form

stimulus figures in the two-frame, missing element task introduced by Di Lollo, V. (1977

Nature, 257, 241-243). Experiment 1 showed that motion-defined figures persisted for about

130 msec after the termination of the stimulus presentation (i.e. after the dots stopped

moving). This was similar to but several tens of milliseconds longer than the visual persistence

of figures which were defined by a luminance difference (luminance-defined figures or

luminance figures) in the same random-dot pattern. Since motion detectors are not found in

the retina or lateral geniculate in primates, our results strongly suggest that visual persistence

is not only a retinal phenomenon but also a cortical one. Experiment 2 investigated the

possible influence of motion aftereffects on the visual persistence of motion figures. The

results showed that coherent movement of the dots over the whole display after the stimulus

offset did not reduce the visual persistence of motion figures, suggesting that the source of this

persistence is not a motion aftereffect. In Experiment 3, visual persistence for the motion-

defined figures was shown to be longer than that for luminance-defined figures independently

of the contrast of the stimulus figure as long as the stimuli could be seen clearly enough. This

suggests that different mechanisms are involved in the visual persistence of motion-defined

and luminance-defined figures.



Shioiri, S., H. Saisho, et al. (2000). “Motion in depth based on inter-ocular velocity differences.”

Vision Research 40(19): 2565-2572.

Two different binocular cues are known for detecting motion in depth. One is disparity change

in time and the other is inter-ocular velocity difference. In contrast to the well known fact of

the use of the disparity cues, no evidence of contribution of inter-ocular velocity differences

for detecting motion in depth has been reported. We demonstrate that motion in depth can be

seen based solely on inter-ocular velocity differences using binocularly uncorrelated random-

dot kinematograms. This indicates that the visual system uses monocular velocity signals for

processing motion in depth in addition to disparity change in time. (C) 2000 Elsevier Science

Ltd. All rights reserved.



Shorter, S. and R. Patterson (2001). “The stereoscopic (cyclopean) motion aftereffect is dependent

upon the temporal frequency of adapting motion.” Vision Research 41(14): 1809-1816.

This study investigated whether the stereoscopic (cyclopean) motion aftereffect (induced by

adaptation to moving binocular disparity information) is dependent upon the temporal

frequency or speed of adapting motion. The stereoscopic stimuli were gratings created from

disparity embedded in a dynamic random-dot stereogram Across different combinations of

stereoscopic spatial frequency, temporal frequency and speed of adapting motion, the duration

of the aftereffect was dependent upon temporal frequency (maximal aftereffect = 1-2 eye s(-

1)). These results support the idea that stereoscopic motion is processed by a cortical

mechanism that computes cyclopean motion energy. (C) 2001 Elsevier Science Ltd. All rights

reserved.

Shotter, J. (1996). “'Now I can go on': Wittgenstein and our embodied embeddedness in the 'hurly-

burly' of life.” Human Studies 19(4): 385-407.

Wittgenstein is not primarily concerned with anything mysterious going on inside people's

heads, but with us simply 'going on' with each other; that is, with us being able to inter-relate

our everyday, bodily activities in unproblematic ways in with those of others, in practice.

Learning to communicate with clear and unequivocal meanings; to send messages; to fully

understand each other; to be able to reach out, so to speak, from within language-game

entwined forms of life, and to talk in theoretical terms of the contacts one has made, as an

individual, with what is out there; and so on - all these abilities are, or can be, later

developments. Wittgenstein's investigations into our pre-individual, pre-theoretical, embodied,

compulsive activities are utterly revolutionary. They open up a vast new realm for empirical

study to do with the detailed and subtle nature of the bodily activities in the 'background' to

everything that we do. The relational character of such pre-theoretical, Ur-linguistic,

spontaneous bodily activities - and the way in which they display us as 'seeing connections'

from within a 'synopsis of trivialities' - is explored through the paradigm of currently

fashionable 3-D random dot autostereograms.



Shrager, J., D. Klahr, et al. (1982). “Segmentation and Quantification of Random Dot Patterns.”

Bulletin of the Psychonomic Society 20(3): 132-132.



Shulman, G. L., J. Schwarz, et al. (1998). “Effect of motion contrast on human cortical responses to

moving stimuli.” Journal of Neurophysiology 79(5): 2794-2803.

The cortical areas activated by motion-defined contours were studied in humans using

positron emission tomography (PET). Subjects observed four types of random dot fields,

displayed through a 21 degrees diam aperture: unidirectional motion of a translating dot field,

motion in opposing directions of two superimposed translating fields, motion in opposing

directions of dots in contiguous spatial regions (motion contrast), producing a square wave

grating defined by motion, and luminance variation of stationary dots in contiguous spatial

regions, producing a square wave grating defined by luminance. Relative to a static dot field,

the unidirectional motion condition activated areas previously described, including areas

17/18, lateral temporal-occipital-parietal cortex (MT/MST), and the superior temporal sulcus.

Motion-defined gratings increased the activation of areas 17/18 and MT/MST, but not the

superior temporal sulcus, and added more dorsal areas in the cuneus, roughly corresponding to

V3/V3a, and ventral areas in the lingual gyrus/collateral sulcus, roughly corresponding to

V2/VP. Luminance defined gratings, relative to a static dot field, activated areas 17/18,

regions in the dorsal cuneus similar to those activated by motion defined gratings, and a region

near the left collateral sulcus, slightly lateral to the motion grating activation. They also

activated a region in the right fusiform gyrus that was more weakly activated by the motion

grating. These results indicate that adding motion contrast to large moving fields increases

activity in areas 17/18 and MT/MST and adds both dorsal and ventral regions that are similar

for motion and luminance defined contours.



Sigmundsson, H., P. C. Hansen, et al. (2003). “Do 'clumsy' children have visual deficits.” Behavioural

Brain Research 139(1-2): 123-129.

Visual processing by 10-11 yr-old children diagnosed on the basis of standardised tests as

having developmental "clumsiness' syndrome, and by a control group of children without

motor difficulties, was tested using three different psychophysical tasks. The tasks comprised

a measure of global motion processing using a dynamic random dot kinematogram, a measure

of static global pattern processing where the position of the target was randomised, and a

measure of static global pattern processing in which the target position was fixed. The most

striking finding was that the group of clumsy children, who were diagnosed solely on the basis

of their motor difficulties, were significantly less sensitive than the control group on all three

tasks of visual sensitivity. Clumsy children may have impaired visual sensitivity in both the

dorsal and ventral streams in addition to their obvious problems with motor control. These

results support the existence of generalised visual anomalies associated with impairments of

cerebellar function. (PsycINFO Database Record (c) 2003 APA, all rights reserved) Record 28

of 30 in PsycINFO 2003/01-2003/06



Sigmundsson, H., P. C. Hansenc, et al. (2003). “Do 'clumsy' children have visual deficits.” Behavioural

Brain Research 139(1-2): 123-129.

Visual processing by 10-year-old children diagnosed on the basis of standardised tests as

having developmental 'clumsiness' syndrome, and by a control group of children without

motor difficulties, was tested using three different psychophysical tasks. The tasks comprised

a measure of global motion processing using a dynamic random dot kinematogram, a measure

of static global pattern processing where the position of the target was randomised, and a

measure of static global pattern processing in which the target position was fixed. The most

striking finding was that the group of clumsy children, who were diagnosed solely on the basis

of their motor difficulties, were significantly less sensitive than the control group on all three

tasks of visual sensitivity. Clumsy children may have impaired visual sensitivity in both the

dorsal and ventral streams in addition to their obvious problems with motor control. These

results support the existence of generalised visual anomalies associated with impairments of

cerebellar function. (C) 2002 Elsevier Science B.V. All rights reserved.



Simmons, D. R., F. A. Kingdom, et al. (1999). “Stereo-form versus stereo-depth deficiency in

isoluminant random-dot stereograms.” Investigative Ophthalmology & Visual Science 40(4):

S418-S418.



Simmons, D. R., F. A. A. Kingdom, et al. (1998). “Is the 'collapse' of stereopsis in isoluminant random-

dot stereograms due to a failure of second-order mechanisms?” Perception 27(12): 1491-1491.



Simons, K. (1981). “A Comparison of the Frisby, Random-Dot-E, Tno, and Randot Circles Stereotests

in Screening and Office Use.” Archives of Ophthalmology 99(3): 446-452.



Simons, K. (1996). “Preschool vision screening: Rationale, methodology and outcome.” Survey of

Ophthalmology 41(1): 3-30.

Although population outcome studies support the utility of preschool screening for reducing

the prevalence of amblyopia, fundamental questions remain about how best to do such

screening. Infant photoscreening to detect refractive risk factors prior to onset of esotropia and

amblyopia seems promising, but our current understanding of the natural history of these

conditions is limited, thus limiting the prophylactic potential of early screening. Screening for

strabismic, refractive and ocular disease conditions directly associated with amblyopia is more

clearly proven, but the diversity of equipment, methods and subject populations studied make

it difficult to draw precise summary conclusions at this point about the efficacy of

photoscreening. Sensory-based testing of preschool-age children exhibits a similar

combination of promise and limitations. The visual acuity tests most widely used for this

purpose are prone to problems of testability and false negatives. Moreover, the utility of

random-dot stereograms has been confused by misapplication, and new small-target

binocularity tests, while attractive, are as yet inadequately field-proven. The evaluation

standard for any screening modality is treatment outcome. However, variables in amblyopia

classification and quantitative definition differences, timing of presentation, nonequivalent

treatment comparisons, and compliance variability have been uncontrolled in virtually all

extant studies of amblyopia treatment outcome, making it difficult or impossible to evaluate

either the relative efficacy of different treatment regimens for amblyopia or the effects of age

on treatment outcome within tile preschool age range. The latter issue is a central one, since

existence of such an age effect is the primary rationale for screening at younger rather than

older preschool ages. The relatively low prevalence of amblyopia makes it difficult to achieve

a high screening yield in terms of predictive value, but functionally increasing prevalence by

selective screening of high risk populations causes further problems. Unless a ''supertest'' can

be devised, with very high sensitivity and specificity, health policy decisions will be required

to determine which of these two characteristics should be emphasized in screening programs.

Performance of screening tests can be optimized, however, with adequate training, perhaps via

instructional videotapes.



Simons, K., K. E. Avery, et al. (1996). “Small-target random dot stereogram and binocular suppression

testing for preschool vision screening.” Journal of Pediatric Ophthalmology & Strabismus

33(2): 104-113.

Background: New, small-target ( 0.3).CONCLUSIONS.

A visual target spot suppresses tOKN by a nonpursuit visual system. Intorsional and

extorsional OKNs were symmetrical.



Swaddle, J. P. and S. Pruett-Jones (2001). “Starlings can categorize symmetry differences in dot

displays.” American Naturalist 158(3): 300-307.

Fluctuating asymmetry is an estimate of developmental stability and, in some cases, the

asymmetry of morphological traits can reflect aspects of individual fitness. As asymmetry can

be a marker for fitness, it has been proposed that organisms could use morphological

asymmetry as a direct visual cue during inter- and intraspecific encounters. Despite some

experimental evidence to support this prediction, the perceptual abilities of animals to detect

and respond to symmetry differences have been largely overlooked. Studying the ability of

animals to perceive symmetry and factors that affect this ability are crucial to assessing

whether fluctuating asymmetry could be used as a visual cue in nature. In this study, we

investigated the ability of wild-caught European starlings Sturnus vulgaris to learn to

discriminate symmetry from asymmetry in random dot patterns through operant learning

experiments. The birds did not possess a spontaneous preference for either symmetry or

asymmetry. The birds learned a symmetry preference, although the learning process took

longer than that previously reported for pigeons Columba livia and was more error prone.

After being trained to discriminate symmetry differences in random dot patterns, birds

successfully transferred their symmetry discrimination abilities to a set of novel stimuli that

they had not previously seen. This indicates that starlings can form a mental categorization of

visual stimuli on the basis of a somewhat generalized symmetry phenomenon. We discuss

these findings in relation to the probability that birds use fluctuating asymmetry as a visual

cue.



Symons, L. A., P. M. Pearson, et al. (1996). “The aftereffect to relative motion does not show

interocular transfer.” Perception 25(6): 651-660.

The motion aftereffect is strongest after viewing a moving field embedded in a patterned

stationary surround, which suggests that relative motion is an important signal for its

generation. The contribution of relative motion to binocular aspects of the motion aftereffect

was assessed. Subjects viewed uniformly moving random dots surrounded by a stationary

random-dot annulus. These displays could be presented in a variety of combinations to each

eye separately or to both eyes, during adaptation and test. It was found that, although the

presence of relative motion during adaptation significantly extended the duration of the

monocular motion aftereffect, it did not augment interocular transfer. The presence of

stationary surround contours in the nonadapting eye did not influence the aftereffect in the

adapting eye. The enhancement provided by stationary surround contours is largely dependent

on their presence during adaptation. The presence or absence of surround contours during the

test phase did not influence the duration of the aftereffect. These findings are consistent with

previous suggestions that the motion aftereffect is, in part, the result of adaptation to relative

motion that occurs relatively early in the visual pathway - before binocular integration.



Szatmary, J., I. Hadani, et al. (1997). “A simple integrative method for presenting head-contingent

motion parallax and disparity cues on Intel x86 processor-based machines.” Spatial Vision

11(1): 43-55.

Rogers and Graham (1979) developed a system to show that head-movement-contingent

motion parallax produces monocular depth perception in random dot patterns. Their display

system comprised an oscilloscope driven by function generators or a special graphics board

that triggered the X and Y deflection of the raster scan signal. Replication of this system

required costly hardware that is no longer on the market. In this paper the Rogers-Graham

method is reproduced with an Intel processor based IBM PC compatible machine with no

additional hardware cost. An adapted joystick sampled through the standard game-port can

serve as a provisional head-movement sensor. Monitor resolution for displaying motion is

effectively enhanced 16 times by the use of anti-aliasing, enabling the display of thousands of

random dots in real-time with a refresh rate of 60 Hz or above. A color monitor enables the

use of the anaglyph method, thus combining stereoscopic and monocular parallax on a single

display without the loss of speed. The power of this system is demonstrated by a

psychophysical measurement in which subjects nulled head-movement-contingent illusory

parallax, evoked by a static stereogram with real parallax. The amount of real parallax

required to null the illusory stereoscopic parallax monotonically increased with disparity.



Taira, M., K. I. Tsutsui, et al. (2000). “Parietal neurons represent surface orientation from the gradient

of binocular disparity.” Journal of Neurophysiology 83(5): 3140-3146.

In order to elucidate the neural mechanisms involved in the perception of the three-

dimensional (3D) orientation of a surface, we trained monkeys to discriminate the 3D

orientation of a surface from binocular disparity cues using a Go/No-go type delayed-

matching-to-sample (DMTS) task and examined the properties of the surface-orientation-

selective (SOS) neurons. We recorded 57 SOS neurons from the caudal part of the lateral bank

of the intraparietal sulcus (area CIP) of three hemispheres of two Japanese monkeys (Macaca

fuscata). We tested 29 of 57 SOS neurons using the square plate of a solid figure stereogram

(SFS) and random-dot stereogram (RDS) without perspective cues; almost all of the tested

neurons (28/29) showed surface orientation selectivity for the SFS and/or the RDS without

perspective cues. Eight of these 28 neurons (28.6%) showed selectivity for both the RDS and

SFS, 7 (25.0%) were dominantly selective for the RDS, and 13 (46.4%) were dominantly

selective for the SFS. These results suggest that neurons that show surface orientation tuning

for the RDS without perspective cues compute surface orientation from the gradient of the

binocular disparity given by the random-dot across the surface. On the other hand, neurons

that show surface orientation tuning for the SFS without perspective cues may represent

surface orientation primarily from the gradient of the binocular disparity along the contours. In

conclusion, the SOS neurons in the area CIP are likely to operate higher order processing of

disparity signals for surface perception by integrating the input signals from many disparity-

sensitive neurons with different disparity tuning.



Takayama, Y. and M. Sugishita (1994). “Astereopsis Induced by Repetitive Magnetic Stimulation of

Occipital Cortex.” Journal of Neurology 241(9): 522-525.

Three healthy subjects underwent repetitive transcranial magnetic stimulation (20 Hz, 1 s)

with a round oil-cooled coil held tangentially against the skull surface 3 or 4 cm above the

inion, while viewing a random-dot stereogram through red-green glasses. The coil was

positioned over the midline of the bilateral superior occipital lobes. All three subjects

experienced loss of stereoscopic perception during stimulation. A stimulus duration of more

than 0.2 s and a stimulus frequency of more than 10 Hz seem to be necessary to disrupt the

cortical mechanisms involved in global stereopsis. Repetitive magnetic stimulation easily and

painlessly produced a reversible disturbance in global stereopsis. The results suggest that the

bilateral superior occipital cortices are involved in the perception of global stereopsis.



Takemura, A., Y. Inoue, et al. (2001). “Single-unit activity in cortical area MST associated with

disparity-vergence eye movements: Evidence for population coding.” Journal of

Neurophysiology 85(5): 2245-2266.

Single-unit discharges were recorded in the medial superior temporal area (MST) of five

behaving monkeys. Brief (230-ms) horizontal disparity steps were applied to large correlated

or anticorrelated random-dot patterns (in which the dots had the same or opposite contrast,

respectively, at the two eyes), eliciting vergence eye movements at short latencies [65.8 =/-

4.5 (SD) ms]. Disparity tuning curves, describing the dependence of the initial vergence

responses (measured over the period 50-110 ms after the step) on the magnitude of the steps,

resembled the derivative of a Gaussian, the curves obtained with correlated and anticorrelated

patterns having opposite sign. Cells with disparity-related activity were isolated using

correlated stimuli, and disparity tuning curves describing the dependence of these initial

neuronal responses (measured over the period of 40-100 ms) on the magnitude of the disparity

step were constructed (n = 102 cells). Using objective criteria and the fuzzy c-means

clustering algorithm, disparity tuning curves were sorted into four groups based on their

shapes. A post hoc comparison indicated that these four groups had features in common with

four of the classes of disparity-selective neurons in striate cortex, but three of the four groups

appeared to be part of a continuum. Most of the data were obtained from two monkeys, and

when the disparity tuning curves of all the individual neurons recorded from either monkey

were summed together, they fitted the disparity tuning curve for that same animal's vergence

responses remarkably well (r(2) : 0.93, 0.98). Fifty-six of the neurons recorded from these two

monkeys were also tested with anticorrelated patterns, and all showed significant modulation

of their activity (P infinity the probability has an inverse power tail in lambda modulated by a

periodic function in ln lambda with a period - In(1 - beta). The new formalism is of interest for

describing the lacunary structures corresponding to the final stages of chemical processes in

low dimensional systems and for the statistics of rare events.



Vogels, R., G. Sary, et al. (2002). “Human brain regions involved in visual categorization.”

Neuroimage 16(2): 401-414.

Categorization of dot patterns is a frequently used paradigm in the behavioral study of natural

categorization. To determine the human brain regions involved in categorization, we used

Positron Emission Tomography to compare regional Cerebral Blood Flow patterns in two

tasks employing patterns that consisted of nine dots. In the categorization task, subjects

categorized novel exemplars of two categories, generated by distorting two prototypes, and

other random dot patterns. In the control task, subjects judged the position of similarly

distorted patterns. Each task was presented at two matched levels of difficulty. Fixation of the

fixation target served as baseline condition. The categorization task differentially activated the

orbito-frontal cortex and two dorsolateral prefrontal regions. These three prefrontal regions

were equally weakly active in the position discrimination task and the baseline condition. The

intraparietal sulcus was activated in both tasks, albeit significantly less in the position

discrimination than in the categorization task. A similar activation pattern was present in the

neostriatum. Task difficulty had no effect. These functional imaging results show that the dot-

pattern categorization task strongly engages prefrontal and parietal cortical areas. The

activation of prefrontal cortex during visual categorization in humans agrees with the recent

finding of category-related responses in macaque prefrontal neurons. (C) 2002 Elsevier

Science (USA).



Volz, H. and J. M. Zanker (1996). “Hyperacuity for spatial localization of contrast-modulated

patterns.” Vision Research 36(9): 1329-1339.

The acuity for localizing the position of a grating and other first order patterns which are

defined directly by the luminance distribution, is much higher than the resolution for such

gratings, This well-described phenomenon usually is referred to as hyperacuity, and is

regarded as a cortical function which is not limited by the optics and the sampling properties

of the eye. Second order patterns which can be defined by the distribution of local contrast

gained some interest because they require more complex processing mechanisms than first

order patterns. We investigated how well gratings and bars which are exclusively defined by

the variation of the local contrast of static random dot patterns can be localized in space. In

this case localization acuity does not reach the precision which is known for first order

patterns. However, the localization of contrast-modulated patterns can bie almost one order of

magnitude better than second order grating resolution, and therefore reaches into the

hyperacuity range. In combination with findings for motion-defined or stereo-defined patterns

it is concluded that the brain mechanisms responsible for the localization of features in the

visual scene have not only access to first order information which is available immediately

from the retinal image, but in addition, to second order information which has to be extracted

from the retinal intensity distribution by some sort of nonlinear processing.



von der Heydt, R., H. Zhou, et al. (2000). “Representation of stereoscopic edges in monkey visual

cortex.” Vision Research 40(15): 1955-1967.

Form perception in random-dot stereograms is based on information that resides in the

correlation between the two images, but is not present in either image alone. We have studied

the coding of stereoscopic figures in the neural activity of areas V1 and V2 of alert behaving

monkeys. While cells in V1 generally responded according to the disparity of the surface at

the receptive field, we found cells in area V2 that responded selectively to the figure edges.

These cells signaled the location and orientation of contrast borders as well as stereoscopic

edges, and were often selective for the direction of the step in depth. We concluded that

stereoscopic edges are explicitly represented in area V2. (C) 2000 Elsevier Science Ltd. All

rights reserved.



Wade, N. J. (1994). “A Selective History of the Study of Visual-Motion Aftereffects.” Perception

23(10): 1111-1134.

The visual motion aftereffect (MAE) was initially described after observation of movements

in the natural environment, like those seen in rivers and waterfalls: stationary objects appeared

to move briefly in the opposite direction. In the second half of the nineteenth century the MAE

was displaced into the laboratory for experimental enquiry with the aid of Plateau's spiral.

Such was the interest in the phenomenon that a major review of empirical and theoretical

research was written in 1911. In the latter half of the present century novel stimuli (like

drifting gratings, isoluminance patterns, spatial and luminance ramps, random-dot

kinematograms, and first-order and second-order motions), introduced to study space and

motion perception generally, have been applied to examine MAEs. Developing theories of

cortical visual processing have drawn upon MAEs to provide a link between pschophysics and

physiology; this has been most pronounced in the context of monocular and binocular

channels in the visual system, the combination of colour and contour information, and in the

cortical sites most associated with motion processing. The relatively unchanging characteristic

of the study of MAEs has been the mode of measurement: duration continues to be used as an

index of its strength, although measures of threshold elevation and nulling with computer-

generated motions are becoming more prevalent. The MAE is a part of the armoury of motion

phenomena employed to uncover the mysteries of vision. Over the last 150 years it has proved

itself immensely adaptable to the shifts of fashion in visual science, and it is likely to continue

in this vein.



Wagemans, J. (1992). “Perceptual Use of Nonaccidental Properties.” Canadian Journal of Psychology-

Revue Canadienne De Psychologie 46(2): 236-279.

Under the assumption of a general viewpoint, particular image properties, such as

cotermination, straightness, and parallelism, can be used to infer, more or less reliably, the

corresponding characteristics in the world. In this paper, the literature about these

nonaccidental properties (NAPs) is reviewed to trace its historical roots, to list the properties

that function as NAPs, and to discuss the psychological evidence for their detection and use.

Against this background, four experiments are reviewed and four are fully described that were

designed to test the perceptual use of skewed symmetry (SS), which results from orthographic

projection of planar bilateral or mirror symmetry (BS). Despite the large symmetry advantage

obtained in all experiments, ss is only perceived as BS-in-depth in cases of closed polygons or

dot patterns with higher-order types of symmetry. In all random dot patterns and in some

symmetric patterns with low "Gestalt", subjects relied on more local groupings which are

qualitatively affine invariant, such as clusters based on proximity or curvilinearity. Based on

previous approaches in the literature and these new findings, I suggest some distinctions

between different ways of using NAPs, which might foster further research.



Wagemans, J. (1993). “Skewed Symmetry - a Nonaccidental Property Used to Perceive Visual Forms.”

Journal of Experimental Psychology-Human Perception and Performance 19(2): 364-380.

Mathematically, skewed symmetry is a nonaccidental property because it can be interpreted as

bilateral symmetry in depth viewed from a nonorthogonal angle. To find out whether this is a

useful property in the perception of visual forms, 4 experiments were designed in which the Ss

had to determine whether 2 symmetric or random patterns were the same regardless of

possible affine transformations between them. The results provided mixed evidence: Although

there was always a large symmetry advantage, skewed symmetry was only perceived as

bilateral symmetry in depth for dot patterns with higher order types of symmetry (Experiment

1), when the dots were connected to form closed polygons (Experiments 2 and 4), or when

they were surrounded by a frame to enhance their planarity (Experiment 3). In other cases, Ss

relied on local groupings on the basis of proximity or curvilinearity, which are qualitatively

affine invariant.



Wagemans, J. (1996). Detection of visual symmetries. Human Symmetry Perception and its

Computational Analyses. C. W. Tyler. Utrecht, VSP: 25-48.



Wagemans, J. (1999). “Toward a better approach to goodness: Comments on Van der Helm and

Leeuwenberg (1996).” Psychological Review 106(3): 610-621.

Some regularities are more salient to the visual system than others. P. A. van der Helm and E.

L. J. Leeuwenberg, (1996) have proposed a new approach that quantifies the goodness of a

pattern's regularity as the number of holographic identities constituting the regulartiy, relative

to the total amount of information needed to describe the pattern. This holographic approach

to goodness was compared with previous approaches and was presented in relation to

metatheoretical issues. These 3 aspects are discussed further here. First, the theory is shown to

contain implausible assumptions and unfortunate gaps with respect to the required processing.

Second, Van der Helm and Leeuwenberg's critique on preceding theories is refuted. Third,

some metatheoretical issues need to he qualified or at least clarified. Together, these concerns

suggest that a better approach to goodness might result from a synthesis of the most useful

aspects of diverse theories of goodness.



Wagemans, J., L. Van Gool, et al. (1990). Visual search in dot-patterns with bilateral and skewed

symmetry. Brogan, David (Ed). (1990). Visual search. (pp. 99 114). Philadelphia, PA, US:

Taylor & Francis. xv, 428 pp.SEE BOOK.

(from the chapter) in the research described here, two different domains, visual search and

symmetry detection, are connected / the notion of symmetry is an important one in perceptual

psychology /// although the experiments that are reported here are primarily focused on the

issue of symmetry detection, some of our results permit us to highlight some important

differences between, on one hand, the processing of bilateral and skewed symmetry, and, on

the other hand, "normal" visual search /// we have tried to unravel the processes that are taking

part in the detection of symmetry by applying different kinds of transformations to random-dot

patterns, resulting in different kinds of regularities / in doing this, we try to show that the two

dominant paradigms in perceptual psychology today (the "cognitive" approach investigating

component processes, and the "ecological" approach investigating regularities and

invariances) are not so different as they seem (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 563 of 887 in PsycINFO 1990-1992



Wagemans, J., L. Van Gool, et al. (1991). “Detection of symmetry in tachiscopically presented dot

patterns: Effects of multiple axes and skewing.” Perception & Psychophysics 50(5): 413-427.



Wagemans, J., L. Van Gool, et al. (1992). “Orientational effects and component processes in symmetry

detection.” Quarterly Journal of Experimental Psychology: Human Experimental Psychology

44a(3): 475-508.

In 4 experiments, 6 Ss discriminated random dot patterns from symmetries defined by

combining 12 axis orientations every 15|| with 7 reflection angles: 0||, yielding bilateral

symmetry (BS), and 3 clockwise and counterclockwise 15|| steps, yielding skewed symmetry

(SS). In Exp 1, with randomized trial order, there was a significant interaction between axis

and skewing angle, indicating that classically observed orientational effects are restricted to

BS and that the orientation of the pointwise correspondences is important. Findings were

replicated in 3 subsequent experiments, which differed in that they used blocks containing

patterns with the same axis (Exp 2), virtual lines orientation (Exp 3), or their combination

(Exp 4). Results suggest a possible reason for the failure of preattentive symmetry detection in

the case of dot patterns with SS. (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 516 of 887 in PsycINFO 1990-1992



Wagemans, J., L. Van Gool, et al. (1993). “Higher-Order Structure in Regularity Detection.” Vision

Research 33(8): 1067-1088.

Four Ss (the 1st author and 3 undergraduates) participated in 3 experiments in which a simple

Euclidean transformation (reflection, translation, rotation) was applied

to collections of 12 dots in such a way that they contained equal lower-order structure, defined on the

pairwise grouping of elements with their partner following transformation (e.g., parallel

virtual lines), but differed in the presence vs absence of higher-order structure, defined on pairs of

pairwise groupings (e.g., virtual quadrangles with correlated angles). Based on the much better

performance levels (d') in the case of additional higher-order structure, the authors conclude that

global regularities are easier to detect when the local correspondences are supported by

higher-order ones formed between them. These enable the lower-order groupings to spread out across

the whole pattern very rapidly (called bootstrapping).



Wagemans, J., L. Vangool, et al. (1991). “Detection of Symmetry in Tachistoscopically Presented Dot

Patterns - Effects of Multiple Axes and Skewing.” Perception & Psychophysics 50(5): 413-

427.

We examined the effects of multiple axes and skewing on the detectability of symmetry in

tachistoscopically presented (100- msec) dot patterns to test the role of normal grouping

processes based on higher order regularities in element positions. In addition to the first-order

regularities of orientational uniformity and midpoint collinearity (Jenkins, 1983), bilateral

symmetry (BS) gives rise to second-order relations between two pairs of symmetric elements

(represented by correlation quadrangles). We suggest that they allow the regularity (i.e., BS)

to emerge simply as a result of the position-based grouping that takes place normally, so that

no special symmetry-detection mechanism has to be postulated. In combination with

previously investigated variables-number and orientation of axes-we introduced skewing

(resulting from orthographic projection of BS) to manipulate the kind and number of higher

order regularities. In agreement with our predictions, the data show that the effect of skewing

angle (varied at three 15-degrees steps, clockwise and counterclockwise) on the preattentive

detectability of symmetry (measured with d') increases as the number of axes decreases. On

the basis of some more specific findings, we suggest that it is not as much the number of

correlation quadrangles that determines the saliency of a regularity as it is the degree to which

they facilitate or "bootstrap" each other.



Wagemans, J., L. Vangool, et al. (1992). “Orientational Effects and Component Processes in Symmetry

Detection.” Quarterly Journal of Experimental Psychology Section a-Human Experimental

Psychology 44(3): 475-508.

In previous research on symmetry detection, factors contributing to orientational effects (axis

and virtual lines connecting symmetrically positioned dots) and component processes (axis

selection and pointwise evaluation) have always been confounded. The reason is the

restriction to bilateral symmetry (BS), with pointwise correspondences being orthogonal to the

axis of symmetry. In our experiments, subjects had to discriminate random dot patterns from

symmetries defined by combining 12 axis orientations (every 15-degrees) with seven

reflection angles (0-degrees, yielding BS, and three clockwise and counterclockwise 15-

degrees steps, yielding skewed symmetry, SS). In Experiment 1, with completely randomized

trial order, a significant interaction between axis and skewing angle was obtained, indicating

that classically observed orientational effects are restricted to BS and that the orientation of

the pointwise correspondences is important. These basic findings were replicated in three

subsequent experiments, which differed in that they used blocks containing patterns with the

same axis (Experiment 2), virtual lines orientation (Experiment 3), or their combination

(Experiment 4). Based on a comparison between the results obtained by these manipulations,

we suggest a possible reason for the failure of preattentive symmetry detection in the case of

dot patterns with SS.



Walker, J. (1980). “The amateur scientist.” Scientific American 242(4): 172-176.

Discusses 2 visual illusions that are based on the tendency of the human perceptual system to

try to impose order on disorder. The first illusion is an array of random dots that, viewed in a

certain way, seem to form concentric circles. The other illusion is seen in the patterns and

motions on a TV screen that is tuned to a channel over which no signal is being transmitted.

The random "snow" that covers the screen can apparently be ordered by the visual process.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 756 of 887 in

PsycINFO 1978-1984



Walker, J. (1980). “Illusions in the Snow - More Fun with Random Dots on the Television Screen.”

Scientific American 242(5): 176-&.



Walker, J. (1980). “Visual Illusions in Random-Dot Patterns and Television Snow.” Scientific

American 242(4): 172-176.



Walker, J. T. and M. W. Kruger (1972). “Figural aftereffects in random-dot stereograms without

monocular contours.” Perception 1(2): 187-192.

Presented random-dot stereograms to 20 male and 20 female undergraduates. The stereograms

produced contour-displacement figural aftereffects in the absence of monocular inspection and

test contours. Such aftereffects were wholly cyclopean (central), since no interaction between

inspection and test contours could occur at any level lower than the area of binocular fusion.

Implications of cyclopean aftereffects for theories of figural aftereffects are discussed.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 859 of 887 in

PsycINFO 1967-1977



Wall, M. and C. S. Jennisch (1999). “Random dot motion stimuli are more sensitive than light stimuli

for detection of visual field loss in ocular hypertension patients.” Optometry and Vision

Science 76(8): 550-557.

Purpose. To determine whether motion detection perimetry or luminance size threshold

perimetry (a test using the motion perimetry method with luminance stimuli) is move sensitive

in detecting visual loss in ocular hypertension patients. Methods. Motion perimetry uses a

customized computer graphics program to detect a subject's ability to identify a coherent shift

in position of moving dots in a defined circular area against a background of fixed dots.

Motion size threshold is defined as the smallest circular area within which dot motion is

detected. Patients respond by touching the area of the computer monitor where they perceive

the stimulus with a light pen. The localization errors are measured as the number of pixels

from target center for each trial. Luminance size threshold perimetry uses the same technique

except the background is dark gray and the stimuli are filled lighter gray circles. We tested one

eye in each of 27 ocular hypertension patients and 27 age-matched normal subjects with both

tests. Our main outcome measures were motion and luminance size thresholds, total deviation

probability plot data, and spatial localization errors. Results. With the total deviation

probability plot analysis, the ocular hypertension patients had a greater number of abnormal

test locations with motion perimetry stimuli than with luminance stimuli. The abnormal test

points were located most often in the superior and inferior nasal regions. Six subjects had

nerve fiber bundle-like defects to motion stimuli whereas three patients had defects with

luminance size threshold perimetry. The ocular hypertension patients had significantly greater

localization errors than the controls with both tests. Conclusions. Using a size thresholding

technique in ocular hypertension patients, random dot motion stimuli appear to be more

sensitive than luminance stimuli. Errors in stimulus localization are significantly increased in

ocular hypertension patients, independent of the stimulus (motion or luminance) used.



Wall, M., C. S. Jennisch, et al. (1997). “Motion perimetry identifies nerve fiber bundlelike defects in

ocular hypertension.” Archives of Ophthalmology 115(1): 26-33.

Objective: To determine whether patients with ocular hypertension (OHT) have elevated

motion perimetry thresholds.Design: Motion perimetry uses a customized computer graphics

program to detect the ability to identify a coherent shift in position of 50% of dots in a defined

circular area against a background of fixed dots. Motion size threshold is defined as the

smallest circular area in which dot motion is detected. Subjects respond by touching the area

of the computer monitor with a light pen where motion stimuli are perceived. Reaction times

(milliseconds) to stimuli and localization error (number of pixels from target center) are also

obtained for each trial.Setting: University hospital ophthalmology clinic.Patients or Other

Participants: Twenty-seven patients with OHT and 27 age-matched normal subjects. One eye

was tested in each subject.Main Outcome Measures: Random dot motion stimuli size

thresholds and total deviation probability plot data, reaction times, and spatial localization

errors.Results: The patients with OHT had more abnormal test points in the to tal deviation

probability plot analysis compared with the controls (P OPP = BW, where > indicates

better performance. That experiment was repeated here in experiment 1 with symmetry axes

not only at vertical but also at horizontal and the two diagonals. It was found overall that BE =

MA > OPP, BW. However, OPP > BW when random trials were included in the analysis but

when they were excluded BW > OPP. This was due to a very high false-alarm rate in

condition BW which could be accounted for if grouping by colour occurs prior to symmetry

detection. In experiment 2 it was shown that vertical-symmetry salience over other

orientations remained about the same as OPP patterns progressively changed into BE patterns

by varying the percentage same polarity between 0% and 100% in 12%-13% steps. Thus, dot-

pair polarity affects performance without affecting relative axis salience, as was also found

recently when dot pattern outlines were masked. All of the data indicate that although opposite

dot polarity does reduce performance slightly, the symmetry-detection mechanism is

remarkably resilient to such perturbation. The high false- alarm rate in the BW condition of

experiment 1 may be accounted for by extremely salient global grouping of dots by luminance

which effectively creates an integral stimulus which is perceptually difficult to break down

into its component dot pairs, prohibiting the required point-by-point matching necessary to

reject symmetry detection. The small detrimental effect of nonmatched polarity might be due

to the polarity differences masking the grouping of dots into 'clumps' on either side of the axis,

a process for which there is a great deal of independent evidence.



Wenderoth, P. (1996). The role of pattern outline in bilateral symmetry detection with briefly flashed

dot patterns. Human Symmetry Perception Perception and its Computational Analysis.

C.W.Tyler. Utrecht, VSP: 49-69.



Wenderoth, P. (1997). “The effects on bilateral-symmetry detection of multiple symmetry, near

symmetry and axis orientation.” Perception 26(7): 891-904.

Examined the effect of different kinds of negative or conjugate stimuli on symmetry detection.

Ss for the 1st 3 experiments were the same 14 college students, while Exp 4 used 25 Ss from

the same populations. Exp 1 involved discrimination of 80-dot patterns with single and

quadruple symmetry from random dot patterns. In Exp 2, 120 random pattern trials were

replaced by 120 trials on which the patterns were 80% symmetrical about a single axis at one

of 90 deg. In Exp 3, the 120 nonsymmetrical trials included 60 that were 80% symmetrical

about the vertical or horizontal or left or right diagonal axes and 60 that were 80%

symmetrical about all 4 axes. Results of Exps 1 and 2 show that performance is better when

targets have 4 axes of symmetry. Results of Exp 3 demonstrated that the hit rate (and RT) was

significantly greater for patterns with quadruple rather than single symmetry patterns. It is

concluded from Exp 4 that symmetry is more detectable in terms of sensitivity in quadruple

rather than in single symmetry patterns. These 4 experiments demonstrate that both sensitivity

and response bias vary considerably in symmetry detection, as a function both of symmetrical

stimuli and of the conjugate instances selected. (PsycINFO Database Record (c) 2002 APA,

all rights reserved) Record 278 of 887 in PsycINFO 1996-1997



Wenderoth, P. (1997). “The role of implicit axes of bilateral symmetry in orientation processing.”

Australian Journal of Psychology 49(3): 176-181.

An important role for the near-effortless perception of bilateral symmetry in human land

other) observers may well be to process the orientation of symmetrical or near-symmetrical

objects which do not have explicitly delineated up-down awes. From psychophysical

investigations of one-and two-dimensional tilt illusions and after-effects, as well as from

orientation discrimination studies, evidence is presented here which points to the existence of

neural substrates which are sensitive to real (or explicit) as well as virtual (or implicit)

contours.



Wenderoth, P. (2000). “The differential effects of simultaneous and successive cueing on the detection

of bilateral symmetry in dot patterns.” Quarterly Journal of Experimental Psychology Section

a-Human Experimental Psychology 53(1): 165-190.

Corballis and Roldan (1975) obtained speeded judgements of whether dot patterns were

bilaterally symmetrical about, or translated across, a line. Reaction times (RTs) were ordered

V (vertical) > D (diagonal) > H (horizontal) where ">" means faster than. Similar results

occurred with blocked axis orientations, suggesting subjects cannot prepare by rotating a

mental frame of reference. Blocking trials may have been ineffective because blocking cannot

provide incremental benefits over those already provided by axis lines. Four experiments show

that the usual axis orientation ordering of V > H > D is markedly attentuated by simultaneous

but not successive axis lines. Also, axis cue lines and axis blocking are not equivalent

treatments. Instead, unblocked line cues require finite processing time whereas, under

blocking, subjects can prepare for the expected orientation. There was no suggestion anywhere

of the V > D > H axis ordering that Corballis and Roldan reported. Successive amis line cues

may only direct attention to the orientation being cued, but simultaneous line cues may change

the stimulus itself, thus providing an additional means of visual processing that facilitates

symmetry detection at non-vertical axis orientations.

Wenderoth, P. (2000). “Monocular symmetry is neither necessary nor sufficient for the dichoptic

perception of bilateral symmetry.” Vision Research 40: 2097-2100.

Expands on the H.B. Barlow and B.C. Reeves (1979) study which showed that bilateral

symmetry (BLS) detection in dot patterns is about equally efficient whether

the displays are viewed monocularly or binocularly. If there is a binocular process which can be

stimulated monocularly, this experiment does not indicate whether symmetry detection occurs

before or after the site of binocular integration. The present study presented stereoscopic 20-dot

patterns, ten dots to each eye, for 150 msec so that "false fusion" rather than rivalry occurred.

Ss judged whether the symmetry axis was tilted left or right of vertical. Three kinds of pattern were

used: SSS patterns were symmetrical in each eye alone and also dichoptically; NNS

patterns were random monocularly but dichoptically symmetrical; and SSN patterns were

symmetrical monocularly but dichoptically non-symmetrical. Orientation judgements were

accurate,

and equally so, for SSS and NNS displays but were extremely poor for SSN displays. A control

experiment showed that poor performance in the SSN condition was not due to the axes of

symmetry being eccentric to the fixation point. Thus, monocular symmetry is neither necessary nor

sufficient for dichoptic BLS perception; and symmetry mechanisms have no access to

monocular signals.



Wenderoth, P. (2002). The role of pattern outline in bilateral symmetry detection with briefly flashed

dot patterns. Tyler, Christopher W. (Ed). (2002). Human symmetry perception and its

computational analysis. (pp. 49 69). Mahwah, NJ, US: Lawrence Erlbaum Associates,

Publishers. vi, 393 pp.SEE BOOK.

(from the chapter) Exp 1 demonstrates that, while the outline shapes of bilaterally symmetrical

dot patterns play a role in symmetry detection, the removal of the outline by a surrounding

random-dot annulus merely reduces performance by a fixed amount. The converse is also true:

performance is almost as good when the symmetrical dot pattern is confined to the

surrounding annulus but is disrupted similarly when the central area is filled with random dots

(Exp 2). In Exp 3, any 1 or more of 3 areas could be filled with vertically symmetrical or

random dots and symmetry was detected reliably only when the central circular area contained

the symmetrical dots. A new paradigm was explored in Exp 4: Ss judged the orientation--left

or right of vertical--of 20-dot symmetrical patterns oriented 1-4 deg left or right of vertical and

with or without surrounding random-outline masks. Surprisingly, the orientation judgments

were extremely precise and outline masking dots made no difference. Exp 5 showed that

performance was even better with just 2 dots and it made no difference whether these were

separated by just under 4 deg or just over 20 deg. It was concluded that while pattern outline

plays some role in dot symmetry detection, the major mechanisms are located near the fovea.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 45 of 887 in

PsycINFO 2002/08-2002/12



Wenderoth, P. and S. Welsh (1998). “The effects of cuing on the detection of bilateral symmetry.”

Quarterly Journal of Experimental Psychology Section a-Human Experimental Psychology

51(4): 883-903.

Pashler (1990) demonstrated that detection of mirror symmetry can be facilitated by precuing

the symmetry axis orientation with a line. In Experiment 1, Pashler's result of a valid pre-

cuing benefit was repeated, but it was also shown that invalid cuing produces performance

costs, relative to a non-informative cue. Experiment 2 showed that the effect is not purely

visual because the letters "V" and "H" can produce the same valid and invalid cuing effects. In

Experiments 3A and 3B, cue and pattern locations were varied, both absolutely and relative to

each other. The results support an explanation for Pashler's atypical finding that horizontal

symmetry can be detected faster than vertical symmetry. They also showed that the cuing

effect is not local, contrary to Pashler's conclusion, but global and hence functionally useful.



Wenderoth, P. and S. Welsh (1998). “Effects of pattern orientation and number of symmetry axes on

the detection of mirror symmetry in dot and solid patterns.” Perception 27(8): 965-976.

It has been postulated that as the number of axes of symmetry in a pattern increases, so pattern

'goodness' increases. Recently, a distinction was made between two different theoretical

accounts of regularity or 'goodness' in relation to patterns with mirror symmetry: the

'transformational' and the 'holographic' models. It was argued that the former predicts a

'goodness' ordering of four > three > two > one whereas the latter predicts four > two > three >

one, where '>' means greater regularity or goodness. In three experiments, we have tested

these predictions. In experiment 1, we measured percentage correct and reaction time to dot

patterns which had one, two, three, or four axes of symmetry and were flashed for 150 ms.

Experiment 2 was identical except that patterns were presented for 2000 ms. In experiment 3,

dot patterns were replaced by solid shapes which also had one, two, three, or four axes of

symmetry. Although it was found that stimuli with four axes clearly allowed superior

performance to that of stimuli with one axis, results obtained with stimuli with two and three

axes were almost identical and in between those obtained with one and four axes. The data

thus support the suggestion that extra axes add 'goodness' to symmetrical patterns but not in a

monotonic fashion.



Werkhoven, P. and J. J. Koenderink (1991). “Visual Processing of Rotary Motion.” Perception &

Psychophysics 49(1): 73-82.

Local descriptions of velocity fields (e.g., rotation, divergence, and deformation) contain a

wealth of information for form perception and ego motion. In spite of this, human

psychophysical performance in estimating these entities has not yet been thoroughly

examined. In this paper, we report on the visual discrimination of rotary motion. A sequence

of image frames is used to elicit an apparent rotation of an annulus, composed of dots in the

frontoparallel plane, around a fixation spot at the center of the annulus. Differential angular

velocity thresholds are measured as a function of the angular velocity, the diameter of the

annulus, the number of dots, the display time per frame, and the number of frames. The results

show a U-shaped dependence of angular velocity discrimination on spatial scale, with minimal

Weber fractions of 7%. Experiments with a scatter in the distance of the individual dots to the

center of rotation demonstrate that angular velocity cannot be assessed directly; perceived

angular velocity depends strongly on the distance of the dots relative to the center of rotation.

We suggest that the estimation of rotary motion is mediated by local estimations of linear

velocity.



Werkhoven, P., H. P. Snippe, et al. (1992). “Visual Processing of Optic Acceleration.” Vision Research

32(12): 2313-2329.

We present data on the human sensitivity to optic acceleration, i.e. temporal modulations of

the speed and direction of moving objects. Modulation thresholds are measured as a function

of modulation frequency and speed for different periodical velocity vector modulation

functions using a localized target. Evidence is presented that human detection of velocity

vector modulations is not directly based on the acceleration signal (the temporal derivative of

the velocity vector modulation). Instead, modulation detection is accurately described by a

two-stage model: a low-pass temporal filter transformation of the true velocity vector

modulation followed by a variance detection stage. A functional description of the first stage

is a second order low-pass temporal filter having a characteristic time constant of 40 msec. In

effect, the temporal low-pass filter is an integration of the velocity vector modulation within a

temporal window of 100-140 msec. A non-trivial link of this low-pass filter stage to the

temporal characteristics of standard motion detection mechanisms will be discussed. Velocity

vector modulations are detected in the second-stage, whenever the variance of the filtered

velocity vector exceeds a certain threshold variance in either the speed or direction dimension.

The threshold standard deviations for this variance detection stage are estimated to be 17% for

speed modulations and 9% for motion direction modulations.



Wesemann, W. and G. Grasemann (1985). “Electrophysiological Determination of Stereopsis with

Random-Dot Stereograms.” Perception 14(1): A38-A38.



Westall, C. A., M. Eizenman, et al. (1993). “Enhancing Veps to Dynamic Random Dot Stereograms.”

Investigative Ophthalmology & Visual Science 34(4): 1354-1354.



Westall, C. A., M. Eizenman, et al. (1998). “Cortical binocularity and monocular optokinetic

asymmetry in early-onset esotropia.” Investigative Ophthalmology & Visual Science 39(8):

1352-1360.

PURPOSE. To investigate the correlation between directional asymmetry in ocular responses

to monocularly viewed optokinetic stimuli (monocular optokinetic nystagmus, MOKN) and

sensory fusion in infants and toddlers with early-onset esotropia.METHODS. Subjects were

14 infants and toddlers with early-onset esotropia (7-26 months old; median, 10 months), and

16 with no esotropia (6-22 months; median, 11 months) who provided control data.

Monocular optokinetic nystagmus in response to a 30 degrees/sec square-wave grating (0.25

cycles/degrees) was measured by electro-oculogram. Sensory fusion was assessed with visual

evoked potentials (VEPs) to random-dot correlograms after correction of the strabismus angle

with Fresnel prisms.RESULTS. All subjects With early-onset esotropia had MOKN with a

faster slow-phase component for temporal-to-nasalward (TN) than nasal-to-temporalward

(NT) motion. Ninety-three percent of subjects had MOKN asymmetry higher than the 95th

percentile of the control group. Of subjects who cooperated with VEP fusion testing, 5

subjects with early-onset esotropia (45%) and 11 control subjects (92%) showed evidence of

sensory fusion.CONCLUSIONS. Symmetrical MOKN did not develop in infants and toddlers

with early-onset esotropia. This deficit existed in most infants who showed sensory-cortical

fusion. These results are consistent with the belief that optokinetic nystagmus asymmetry may

not be associated with a deficit in the cortical fusion facility, but rather with deficits in

binocular pathways projecting to MOKN control centers. These deficits may be associated

with abnormal processing subsequent to sensory fusion or with abnormal processing in motion

pathways, which mn parallel to sensory fusion pathways.



Westermann, R. and W. Hager (1985). “Kontexteffekte bei numerischen und verbalen Beurteilungen

der Groe-Se von Punktmengen. / Context effects of numerical and verbal judgments on the

magnitude of dot patterns.” Psychologische Beitrage 27(4): 575-584.

Investigated the hypothesis that context influences perceptual judgment in direct estimations

of physical magnitude as well as in verbal judgments given within specified categories. 120

students (primarily 1st and 2nd semester psychology students) were presented with 5 random

patterns of 35 to 135 dots. Random patterns of 2, 20, and 75 dots were used as context stimuli.

50% of the Ss were asked to judge the number of dots by checking 1 of 7 categories (from

very, very large to very, very small). The other half of the Ss were asked to estimate the

number of dots as accurately as possible and to write down their estimates. Despite very large

interindividual variability of direct estimation means, similar context effects were observed for

both perceptual judgment methods. A context stimulus that is somewhat smaller than the

stimulus series (20 dots) results in higher estimations, but with an extremely small context

stimulus (2 dots), this contrast effect seems to disappear again. Recommendations for further

investigations are provided. (English & French abstracts) (15 ref) (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 656 of 887 in PsycINFO 1985-1987



Westheimer, G. (1984). “Spatial vision.” Annual Review of Psychology 35: 201-226.

Distinguishes between studies of visual sensitivity (the S determines whether, during a

stimulus presentation, the field remains uniform or is spatially differentiated) and those of

spatial vision (the S makes a distinction between specific spatial configurations) in this review

of the literature. The psychophysical study of spatial vision has a minimum of definitional

overhead but has its roots in neuron doctrine and studies of spatial filtering and channels.

Binocular vision, developmental capabilities, and amblyopia have received extensive attention

from researchers. Methods of measurement include the visual evoked response and behavioral

techniques. New viewpoints are emerging from the study of visual pathways and fovea and

retinal periphery. The simplest spatial judgment is the detection of target displacement, but

global questions of how patterns emerge from ensembles of random dots are also being

studied. Computational theories propose 3 levels of understanding visual information

processing: hardware implementation, representation, and algorithm and computational

theory. It is suggested that vision research may develop into dichotomous tracks of theory and

experiment. (4 p ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record

710 of 887 in PsycINFO 1978-1984



Westheimer, G. (1991). “Visual Discrimination of Fractal Borders.” Proceedings of the Royal Society

of London. B. 243(215-219).

The idea of fractals and fractal dimension are here translated into the realm of visual

psychophysics. ....



Westheimer, G. (2001). “The Fourier theory of vision.” Perception 30: 531-541.

The historical roots of the Fourier theory of spatial visual perception are traced. The

development of the underlying concepts and the psychophysical experiments that led to them,

and that they in turn spawned, are examined, as well as their relation to the current knowledge

of neural substrates in the retina and primary visual cortex. Allowing nonlinearities or even

substituting other types of basis functions does not eliminate the difficulties faced by any

theory of visual perception that is built on the notion of fixed spatial filters.



Westheimer, G. (2003). “Meridional anisotropy in visual processing: implications for the neural site of

the oblique effect.” Vision Research 43(22): 2281-2289.

The contention is examined that the oblique effect, i.e., the well-known performance deficit in

detecting orientation difference in oblique lines as compared to vertical and horizontal ones,

has its origin in a relative deficiency of neurons with obliquely-oriented receptive fields in the

primary visual cortex. Psychophysical observations demonstrate a prominent oblique effect

also in visual tasks involving widely-separated elements and other stimuli that would elicit

little or no response in oriented neurons in the visual cortex. Conversely, some tasks, e.g.

position discrimination, exhibit no oblique effect even with short, high-contrast lines. When

the comparison with the reference can be accomplished during a single brief exposure rather

than sequential ones, thresholds for orientation differences between adjacent contours in

oblique meridians are also elevated compared to those in the vertical and horizontal, but to a

lesser extent. In one particular texture discrimination task some but not all observers have a

conspicuous oblique effect. The discrimination only of the direction of streaming random dots,

not of their speed, is poorer for motions in oblique meridians. The findings imply that the

neural locus for the oblique effect is more central than the primary visual cortex. (C) 2003

Elsevier Ltd. All rights reserved.



Westheimer, G. and C. Wehrhahn (1994). “Discrimination of Direction of Motion in Human Vision.”

Journal of Neurophysiology 71(1): 33-37.

1. Differences as low as 0.5 degrees can be discriminated in the direction of motion of a single

spot of light moving with optimum speed and seen in the fovea for <250 ms. There is no

improvement for a cloud of random dots or a short line. 2. For high velocities the thresholds

approach those for the discrimination of orientation of a single line, when the length of the line

is equal to the excursion of the dot and when the line is shown for the same duration. 3. The

sensitivity for orientation of line of motion of a moving spot also shares two other attributes

with that for the orientation of a single solid line of similar temporal and spatial extents:

discrimination is seriously impaired when flanked by related close-by stimuli, and sensitivity

is subject to simultaneous orientation contrast. 4. It is suggested that the orientation both of

features and of lines of motion is processed by the same mechanism.



Whitaker, D. and H. Walker (1988). “Centroid Evaluation in the Vernier Alignment of Random Dot

Clusters.” Vision Research 28(7): 777-784.



Whitney, D., P. Cavanagh, et al. (2000). “Temporal facilitation for moving stimuli is independent of

changes in direction.” Vision Research 40(28): 3829-3839.

A flash that is presented aligned with a moving stimulus appears to lag behind the position of

the moving stimulus. This flash-lag phenomenon reflects a processing advantage for moving

stimuli (Metzger, W. (1932) Psychologische Forschung 16, 176-200; MacKay, D. M. (1958)

Nature 181, 507-508; Nijhawan, R. (1994) Nature 370, 256-257; Purushothaman, G., Patel,

S.S., Bedell, H.E., & Ogmen, H. (1998) Nature 396, 424; Whitney, D. & Murakami, I. (1998)

Nature Neuroscience 1, 656-657). The present study measures the sensitivity of the illusion to

unpredictable changes in the direction of motion. A moving stimulus translated upwards and

then made a 90 degrees turn leftward or rightward. The flash-lag illusion was measured and it

was found that, although the change in direction was unpredictable, the flash was still

perceived to lag behind the moving stimulus at all points along the trajectory, a finding that is

at odds with the extrapolation hypothesis (Nijhawan, R. (1994) Nature 370, 256-257). The

results suggest that there is a shorter latency of the neural response to motion even during

unpredictable changes in direction. The latency facilitation therefore appears to be

omnidirectional rather than specific to a predictable path of motion (Grzywacz, N. M. &

Amthor, F. R. (1993) Journal of Neurophysiology 69, 2188-2199). (C) 2000 Elsevier Science

Ltd. All rights reserved.



Wiesenfelder, H. and R. Blake (1991). “Apparent motion can survive binocular rivalry suppression.”

Vision Research 31(9): 1589-1599.

Examined the effect of suppression on short- and long-range apparent motion. For short-range

motion, 6 observers dichoptically viewed a random-dot cinematogram and a rival target. On

keypress, the 1st frame of the cinematogram was replaced by the 2nd frame. Ss judged the

direction of motion, which was governed by the initial position of the central region.

Performance was well above chance during both dominance and suppression. For long-range

motion, 4 Ss rated the motion produced by sequentially flashing 2 small spots, with the 1st

spot contained within a rivalrous region. Suppression reduced but did not prevent perception

of this motion. Presenting the 2nd motion frame to both eyes weakened both forms of motion.

Suppression of the 1st frame and presentation of the 2nd frame to both eyes combined to block

motion perception. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record

534 of 887 in PsycINFO 1990-1992



Wiesenfelder, H. and R. Blake (1991). “Apparent Motion Can Survive Binocular-Rivalry

Suppression.” Vision Research 31(9): 1589-1599.

For short-range motion, observers dichoptically viewed a random-dot cinematogram and a

rival target. Upon keypress, the first frame of the cinematogram was replaced by the second

frame. Observers judged the direction of motion, which was governed by the initial position of

the central region. Performance was well above chance during both dominance and

suppression. For long-range motion, observers rated the motion produced by sequentially

flashing two small spots, with the first spot contained within a rivalrous region. Suppression

reduced but did not prevent perception of this motion. Presenting the second motion frame to

both eyes weakened both forms of motion.



Williams, D., S. Tweten, et al. (1991). “Using Metamers to Explore Motion Perception.” Vision

Research 31(2): 275-286.

We examined conditions under which two quite different types of random-dot cinematograms

were perceptually matched. In one stimulus type, directions of motion were defined by a

uniform distribution; in the other, directions were drawn from a discrete set of just a few,

widely separated directions. Cinematograms whose range of uniformly distributed directions

lay between 180 and 270 deg could be matched by cinematograms containing just 6-10

discrete directions. The number of discrete directions required for a match was a

nonmonotonic function of the range of directions present in the other cinematogram. The

results are consistent with a line-element model in which the outputs of 12 direction-selective

mechanisms, each with a half-amplitude half-bandwidth of 30 deg, are combined nonlinearly

to produce the percept of motion.



Williams, D. W. and R. Sekuler (1984). “Coherent global motion percepts from stochastic local

motions.” Vision Research 24(1): 55-62.

Studied the percept of global, coherent motion that resulted when many different localized

motion vectors were combined with dynamic random dot kinematograms whose elements took

independent, random walks of constant step size; their directions of displacement were drawn

from a uniform distribution. Four Ss were tested. The tendency to see global, coherent flow

along the mean of the uniform distribution varied with the range of the distribution.

Psychometric functions were obtained with kinematograms having various step sizes and

element densities. The changes in the psychometric function with step size and density were

consistent with S. Ullman's (1979) minimal map theory of motion correspondence. (10 ref)

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 706 of 887 in

PsycINFO 1978-1984



Wilson, H. R., B. Krupa, et al. (2000). “Dynamics of perceptual oscillations in form vision.” Nature-

Neuroscience 3(2): 170-176.

Certain periodic dot patterns (Marroquin patterns) generate a percept of dynamically

oscillating circles. Here, the authors show psychophysically that circles are perceived in these

patterns only around specific points that are quantitatively predicted by a neural model of

configural units hypothesized to reside in cortical area V4. Selective attention effects are

evident in V4 at the single neuron level and are believed to result from inhibitory competition

in parallel networks. This suggests that the Marroquin illusion might arise from competitive

interactions among V4 concentric units. Circles superimposed on the pattern mask perception

of illusory circles. A neural model of lateral inhibitory interactions among V4 configural units

showing spike-frequency adaptation quantitatively accounts for the human data. The model is

consistent with ideas on the neural basis of attention in V4, and it suggests that attention may

be biased via neuromodulation of slow hyperpolarizing potentials in cortical neurons.



Wilson, H. R., G. Loffler, et al. (2001). “An inverse oblique effect in human vision.” Vision Research

41(14): 1749-1753.

In the classic oblique effect contrast detection thresholds, orientation discrimination

thresholds, and other psychophysical measures are found to be smallest for vertical or

horizontal stimuli and significantly higher for stimuli near the +/- 45 degrees obliques. Here

we report a novel inverse oblique effect in which thresholds for detecting translational

structure in random dot patterns [Glass, L. (1969). Moire effect from random dots. Nature,

223, 578-580] are lowest for obliquely oriented structure and higher for either horizontal or

vertical structure. Area summation experiments provide evidence that this results from larger

pooling areas for oblique orientations in these patterns. The results can be explained

quantitatively by a model for complex cells in which the final filtering stage in a filter-rectify-

filter sequence is of significantly larger area for oblique orientations. (C) 2001 Elsevier

Science Ltd. All rights reserved.



Wilson, H. R. and F. Wilkinson (1998). “Detection of global structure in Glass patterns: implications

for form vision.” Vision Research 38(19): 2933-2947.

Glass (Nature 1969,223:578-580) patterns are random dot stimuli that generate a percept of

global structure. To study the mechanisms underlying this global form perception, concentric,

radial, hyperbolic, and parallel Glass patterns were constructed. Thresholds for detecting each

type of pattern were measured by degrading the patterns through the addition of noise.

Concentric patterns yielded the lowest thresholds for all subjects, while radial and hyperbolic

patterns produced somewhat higher thresholds. For all subjects the parallel patterns produced

the highest thresholds. Threshold measurements as a function of the area containing pattern

structure provided evidence for global pooling of orientation information in the detection of

radial and concentric Glass patterns but only local pooling in the detection of parallel patterns.

Monte-Carlo simulations demonstrate that plausible neural models can accurately predict the

data. These models indicate that the visual system contains networks that pool orientation

information within regions 3.5-4.5 degrees in diameter in central vision. This pooling is

organized to extract cross-shaped, X-shaped, and quasi-circular forms from the retinal image.

The results are in good agreement with recent single unit physiology of primate al ea V4, an

intermediate level of the form vision pathway. (C) 1998 Elsevier Science Ltd. All rights

reserved.



Wilson, H. R. and F. Wilkinson (2002). “Symmetry perception: a novel approach for biological

shapes.” Vision Research 42(5): 589-597.

The majority of quantitative studies on symmetry perception have employed random dot

patterns, yet symmetrical random patterns are not common in nature. Here we explore

symmetry perception utilizing SLIMS of radial frequency (RF) patterns to define complex

shapes. When a pair of RF patterns with different frequencies are added, the relative phase of

the two components provides a precise measure of the degree of deviation from bilateral

symmetry. Sums of RF2-RF7 define such diverse biological shapes as human heads, animal

heads, torsos, and many fruit, so discrimination of symmetries defined by these patterns is

highly relevant to biological vision. Here we show that symmetry discrimination during brief

presentations is best for RF2 + RF3 but becomes impossible for RF2 + RF7. Further

experiments demonstrate that the underlying neural mechanisms differ from those involved in

random dot symmetry detection. These results were used to predict symmetry thresholds for

deviations from bilateral symmetry of head shapes based on a principal components analysis

of 30 female heads. Human V4 is hypothesized to be the site for symmetry discrimination of

RF patterns but not of random dot patterns. (C) 2002 Elsevier Science Ltd. All rights reserved.



Wilson, H. R. and F. Wilkinson (2003). “Further evidence for global orientation processing in circular

Glass patterns.” Vision Research 43(5): 563-564.



Wilson, H. R., F. Wilkinson, et al. (1997). “Concentric orientation summation in human form vision.”

Vision Research 37(17): 2325-2330.

Psychophysical data demonstrate that orientation information in concentric, random-dot Glass

patterns is summed linearly to extract a global form percept, Surprisingly, no such global

pooling was found for Glass patterns with parallel structure, A simple neural model explains

these results and agrees with recent V4 single unit physiology, As V4 provides the major input

to IT, global concentric units may play an important role in analyzing complex images such as

faces, In support of this possibility, deficits in the perception of concentric Glass patterns have

recently been linked to prosopagnosia. (C) 1997 Elsevier Science Ltd.



Wilson, H. R., F. Wilkinson, et al. (1997). “Rapid Communication: Concentric orientation summation

in human form vision.” Vision Research 37(17): 2325-2330.

Studied how primary visual cortex contour information converted into a form suitable for

global pattern responses in inferior temporal cortex in human vision by measuring thresholds

for Glass (L. Glass, 1969 and L. Glass and R. Perez, 1973) pattern detection. Thresholds for

Glass patterns containing concentric, radial, hyperbolic, and parallel structure were measured

among 7 Ss. Control experiments using parallel Glass patterns were also conducted. Results

show that thresholds fo detecting patterns in noise provide clear evidence for global

summation of concentrically arranged orientations in human vision. However, there is no

evidence for global pooling in the detection of parallel Glass patterns, thus suggesting that

parallel structure is only processed locally.



Wilson, J. L. (1981). “Visual persistence at both onset and offset of stimulation.” Perception and

Psychophysics 30(4): 353-356.

In each of 2 experiments, 15 university students identified dot bigrams appearing within or

disappearing from random dot patterns. Each letter could be split into 2 predefined parts; the

cues concerning the complete letter were minimized in each half. Identification performance

was investigated as the interval between the appearance or disappearance of bigram halves

was varied in the range 0-300 msec. Results indicate that the durations of persistence of

information concerning stimulus onset and offset are at least 180 and 120 msec, respectively.

(19 ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 748 of 887 in

PsycINFO 1978-1984



Wilson, J. T. (1983). “Effects of stimulus luminance and duration on responses to onset and offset.”

Vision Research 23(12): 1699-1709.

Six experiments with 70 Ss investigated the perception of on- and offset of dot bigrams within

random-dot patterns. On and offset persistences were studied at 2 levels of stimulus

luminance: 8- and 45-ft L (27 and 154 cd/m-2). Similar performance was obtained for targets

defined by on- and offset; the lower luminance produced a decrement in response at offset.

On- and offset perceptibilities were studied at 6 stimulus durations between 20 and 1,260

msec. Effects of stimulus duration were distinguished from masking effects due to pattern

offset. Decreasing stimulus duration had little or no effect on recognition of bigrams defined

by onset but produced a large decrement in the perceptibility of bigrams defined by offset. A

brief stimulus therefore seems to give a relatively strong on-response and a weak off-response.

Results are consistent with electrophysiological findings concerning on- and off-responses and

contrast with the idea that persistence consists of a decaying trace of the steady-state

properties of the stimulus. (59 ref) (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 702 of 887 in PsycINFO 1978-1984



Wisniewski, I. and H. Ono (1995). “Local and Global Stereopsis in Random-Dot Stereograms with

Matched and Unmatched Elements.” Investigative Ophthalmology & Visual Science 36(4):

S365-S365.



Wist, E. R., W. H. Ehrenstein, et al. (1998). “A computer-assisted test for the electrophysiological and

psychophysical measurement of dynamic visual function based on motion contrast.” Journal

of Neuroscience Methods 80(1): 41-47.

A new test is described that allows for electrophysiological and psychophysical measurement

of visual function based on motion contrast. In a computer-generated random-dot display,

completely camouflaged Landolt rings become visible only when dots within the target area

are moved briefly while those of the background remain stationary. Thus, detection of

contours and the location of the gap in the ring rely on motion contrast (form-from-motion)

instead of luminance contrast. A standard version of this test has been used to assess visual

performance in relation to age, in screening professional groups (truck drivers) and in clinical

groups (glaucoma patients). Aside from this standard version, the computer program easily

allows for various modifications. These include the option of a synchronizing trigger signal to

allow for recording of time-locked motion-onset visual-evoked responses, the reversal of

target and background motion, and the displacement of random-dot targets across stationary

backgrounds. In all instances, task difficulty is manipulated by changing the percentage of

moving dots within the target (or background). The present test offers a short, convenient

method to probe dynamic visual functions relying on surprathreshold motion-contrast stimuli

and complements other routine tests of form, contrast, depth, and color vision. (C) 1998

Elsevier Science B.V. All rights reserved.



Wist, E. R., J. D. Gross, et al. (1994). “Motion Aftereffects with Random-Dot Chequerboard

Kinematograms - Relation between Psychophysical and Vep Measures.” Perception 23(10):

1155-1162.

A random-dot chequerboard kinematogram was used to investigate the effect of motion

adaptation both on evoked potentials and on motion aftereffects (MAEs). The experimental

paradigm used allowed simultaneous measurement of both variables. Each adaptation period

was followed by a series of 5 short test stimuli to which evoked potentials were recorded.

Motion aftereffects were observed in the intervals between test stimuli. An inverse

relationship between mean N2-P1 amplitude and mean reported MAEs was found as a

function of adaptation durations of 1.4, 5.6, and 17.5 s. When the shortest and longest

adaptation durations were compared, this relationship held for thirteen of fourteen subjects

tested when adaptation-motion and test-motion directions corresponded and for twelve of

fourteen subjects when they were opposed. The possibility that the effect of motion adaptation

on N2-P1 amplitude was due to local luminance-contrast adaptation is discussed and shown to

be unlikely. The suitability of this paradigm for the combined psychophysical and

electrophysiological assessment of disturbances in motion perception is discussed.



Wist, E. R., J. D. Gross, et al. (1994). “Motion aftereffects with random-dot chequerboard

kinematograms: Relations between psychophysical and VEP measures.” Perception 23(10):

1155-1162.

Used a random-dot checkerboard kinematogram to study the effect of motion adaptation (MA)

both on evoked potentials (EPs) and on motion aftereffects (MAEs). This paradigm allowed

simultaneous measurement of both variables. Each adaptation period was followed by 5 short

test stimuli to which EPs were recorded. MAEs were observed in the intervals between test

stimuli. An inverse relationship between mean N2-P1 amplitude and mean reported MAEs

was found as a function of adaptation durations of 1.4, 5.6, and 17.5 sec. When the shortest

and longest adaptation durations were compared, this relationship held for 13 of 14 Ss (aged

13-55 yrs) tested when adaptation-motion and test-motion directions corresponded and for 12

of 14 Ss when they were opposed. The effect of MA on N2-P1 amplitude due to local

luminance-contrast adaptation is shown to be unlikely. (PsycINFO Database Record (c) 2002

APA, all rights reserved) Record 414 of 887 in PsycINFO 1993-1995



Wist, E. R., M. Schrauf, et al. (2000). “Dynamic vision based on motion-contrast: changes with age in

adults.” Experimental Brain Research 134(3): 295-300.

Data are presented for a computerized test of dynamic vision in a sample of 1006 healthy

subjects aged between 20 and 85 years. The test employed a form-from-motion stimulus: i.e.,

within a random-dot display, Landolt rings of the same average luminance as their

surroundings become visible only when the dots within the ring are moved briefly, while those

of the surround remain stationary. Thus, detection of gap location is based upon motion

contrast (form-from-motion) rather than luminance contrast. With the size and exposure

duration of the centrally presented ring held constant, motion contrast was manipulated by

varying the percentage (between 20 and 100%) of moving dots within the ring. Subjects

reported gap location (left, right, top, bottom). A gradual decline of dynamic vision with age

was found for all motion-contrast levels. Beyond 70 years of age, chance-level performance

occurred in almost half of the subjects. The data provide the basis for applications including

diagnostic screening for glaucoma, visual disturbances in brain-damaged patients, as well as

assessment: of the dynamic vision of drivers of motor vehicles and athletes.



Wojciechowski, R., G. L. Trick, et al. (1995). “Topography of the Age-Related Decline in Motion

Sensitivity.” Optometry and Vision Science 72(2): 67-74.

Purpose. We examined whether the decline in motion sensitivity in the elderly is equivalent

for different visual field locations. Methods. High velocity (28 degrees/s) random dot

kinematograms (RDK's) were used to measure direction discrimination thresholds for 5

locations in the visual field (1 position centered on fixation and 4 locations each centered 18

degrees from fixation in the nasal, temporal, superior, and inferior quadrants). Differential

luminance sensitivity was assessed by automated perimetry. Younger (N = 15, mean age =

22.9 +/- 1.3 years) and older (N = 13, mean age = 66.6 +/- 4.5 years) subjects were studied.

Results. Motion sensitivity varied with test location for both younger and older subjects, but

sensitivity was significantly lower in older individuals. The largest age-related reduction in

sensitivity was in the central location, whereas the smallest decline was in the superior

position. No significant correlations between motion and differential luminance sensitivity

were evident. Conclusions. There is a significant age-related deterioration in visual sensitivity

to motion which is more pronounced in the central visual field than in some regions of the

more peripheral field. Although both motion and differential luminance sensitivity decrease

with age, the rate and the magnitude of the loss differ for these two visual functions.



Wolfe, J. M. and R. Held (1982). “Binocular adaptation that cannot be measured monocularly.”

Perception 11(3): 287-295.

An experiment with 9 19-57 yr olds used the tilt aftereffect (TAE) to demonstrate the

existence of a purely binocular process in human vision. A purely binocular process is a

process that can be activated only by matched inputs to the 2 eyes and is insensitive to

monocular stimulation. The TAE can be produced by exposure to a bipartite field with the top

tilted to the left of vertical, the bottom to the right. After such adaptation, a pair of colinear

lines appears bent in the opposite direction. A cyclopean random-dot stereogram can be used

as an adapting stimulus. It produces a 2| TAE when a cyclopean test stimulus is used and a 1|

TAE when a binocular but noncyclopean test stimulus is used. If the same noncyclopean

pattern is viewed monocularly, no TAE is measurable. The TAE does not transfer from

cyclopean adaptation to monocular testing. Apparently, cyclopean stimuli activate a purely

binocular process that cannot be activated by either eye alone. (24 ref) (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 730 of 887 in PsycINFO 1978-1984



Wong, B. P. H., R. L. Woods, et al. (2002). “Stereoacuity at distance and near.” Optometry and Vision

Science 79(12): 771-778.

Purpose. Because previous studies have reported conflicting evidence, we examined a possible

difference in stereoacuity between distance and near, in particular using a random-dot display.

We compared distance and near stereoacuities using identical presentation formats at the two

distances. Methods. Twelve young adults with low, stable refractive errors and apparently

normal binocular vision participated. Stereoacuity was determined with A Mentor B-VAT II

using Random Dot E (BVRDE) and Contour Circles (BVC) stereograms presented on a

standard monitor (25 X 19.3 cm) at 518 cm (distance-habitual) and a small monitor (2.0 X

1.4cm) at 40 cm (near-habitual). To examine whether accommodation-convergence influenced

stereoacuity, testing at 40 cm was repeated with the addition of +2.50 DS lenses and base-in

prisms (near-compensated) that created the same accommodation and convergence demands

as for distance-habitual viewing. Results. The two stereotests produced similar findings.

Stereoacuity was not significantly different for distance-habitual and near-habitual viewing of

the BVRDE (p = 0.43) and BVC (p = 0.79) stereotests. Near-compensated stereoacuity was

worse than near-habitual (BVRDE, p = 0.005; BVC, p = 0.004) and distance-habitual

(BVRDE, p = 0.05; BVC, p = 0.003) for both stereotests. Because near stereoacuity with

yoked prisms (control condition) was the same as without prism (near-habitual), prism-

induced optical distortions cannot account for the difference. Conclusions. Stereoacuity was

not different at distance and near under normal viewing conditions. The conflict between

subject knowledge of target proximity and the optically-induced relaxation of accommodation

and convergence, or an inaccurate accommodative-convergence response, might have caused

poor near-compensated stereoacuity.



Wong, E. and N. Weisstein (1984). “Flicker induces depth: Spatial and temporal factors in the

perceptual segregation of flickering and nonflickering regions in depth.” Perception and

Psychophysics 35(3): 229-236.

Conducted 3 experiments to investigate the depth segregation produced by flicker. Exp I, with

7 undergraduates, investigated the spatiotemporal tuning of depth segregation produced by

flicker; Exp II, with 7 undergraduates, examined the effect of amplitude of temporal

modulation on depth segregation between flickering and nonflickering regions; and Exp III,

with 7 undergraduates examined the effect of luminance differences on the amount of depth

perceived between flickering and nonflickering regions. Results indicate that if some regions

of a random-dot field are flickered, then the nonflickering areas appear to stand out in depth in

front of the flickering regions. This perception of depth is optimal within a limited range of

temporal frequencies. The average temporal luminance of the flickering and nonflickering

regions was kept equal, so the depth segregation is not due to luminance difference. The

magnitude of perceived depth is affected by the percentage of luminance modulation: depth is

maximal at 100% modulation and diminishes as the percent modulation decreases. The tuning

function was charted using alternating flickering and nonflickering random-dot bars and found

it to be similar to those of visual channels most sensitive to high temporal frequency. (15 ref)

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 696 of 887 in

PsycINFO 1978-1984



Wood, J. M. and M. A. Bullimore (1995). “Changes in the Lower Displacement Limit for Motion with

Age.” Ophthalmic and Physiological Optics 15(1): 31-36.

Previous studies have alleged that the ability to perceive motion remains constant with age.

We investigated the effect of age on minimum displacement thresholds using computer-

generated random dot stimuli in 91 healthy, visually normal subjects (age range 21-82 years).

High and low contrast visual acuity and letter contrast sensitivity were also tested. We found

that minimum displacement thresholds increased significantly at a rate of 0.07 log min arc per

decade (approximate to 17%). The relationship between age and performance was very similar

for all visual tests.



Wright, K. W., P. M. Edelman, et al. (1994). “High-Grade Stereo Acuity after Early Surgery for

Congenital Esotropia.” Archives of Ophthalmology 112(7): 913-919.

Objective: To evaluate the effectiveness of very early surgery for establishing straight eyes

and sensory fusion in patients with congenital esotropia.Design: X review of consecutive

patients with congenital eso tropia who underwent surgery between 13 and 19 weeks of

age.Setting: A children's hospital with a teaching affiliation.Patients: Seven patients who had

surgery between 13 and 19 weeks of age.Intervention: A bilateral medial rectus recession

through a fornix incision with recessions ranging from 5.75 to 6.5 mm in infants younger than

6 months of age.Main Outcome Measures: Sensory fusion as measured by stereo acuity and

Worth four-dot testing and motor alignment within 8 prism diopters.Results: Five of the seven

patients achieved essentially straight eyes with tropias of less than 8 prism diopters after one

horizontal surgery. Five patients cooperated with sensory testing, and all showed stereo

acuities that ranged from 400 to 40 seconds of are. Three children had evidence of high-grade

stereo acuity by showing stereopsis on random dot stereograms (Randot, Stereo Optical Co,

Chicago, Ill) and by fusing the Worth four-dot test at distance and near range. Two of the

patients with high-grade stereo acuity achieved a stereo acuity of 40 seconds of are by Titmus

testing; however, one had a late reduction of stereo acuity to 70 seconds of are.Conclusion:

Very early surgery can result in excellent motor alignment and high-grade stereo acuity in

some patients with congenital esotropia.



Wuest, R. M., A. M. Kappers, et al. (1993). “Visuomotor control of the relative movement of random-

dot patterns.” Perceptual and Motor Skills 77(1): 275-298.

Two experiments examined human performance in controlling optical relative movement

(RM). The aim was to test the influence of different kinds of RM on visually controlled

steering tasks. Within adjacent displays on a computer screen, random dot patterns moved in a

fixed direction at continually changing speeds (Exp 1) or at constant speed and in continually

changing directions (Exp 2). Ss were required to compensate for the unpredictable

modulations of the pattern movement by means of an isometric joystick. The task for the 2

observer Ss was to adjust relative movements involving pure translation, symmetric

convergence, divergence, or shear. Results indicate that the task performance was not

dependent on the special kind of relative movement. However, performance was significantly

higher in tasks where directionally disturbed RM had to be controlled compared with those

situations in which RM varied with respect to speed. (PsycINFO Database Record (c) 2002

APA, all rights reserved) Record 474 of 887 in PsycINFO 1993-1995

Wust, R., A. M. L. Kappers, et al. (1992). “Visually Controlled Matching of Pattern Movement.”

Perception & Psychophysics 51(6): 569-579.

Subjects were asked to match the speeds of two moving random-dot patterns seen through

circular apertures. The speed of one pattern that moved horizontally toward the right of a

computer screen changed continuously. The speed of this pattern represented the target. It was

to be matched with the speed of the second pattern, which moved in the opposite direction.

The subject controlled the speed of the second pattern by means of an isometric joystick. The

distance between the apertures on the screen as well as the subject's distance from the screen

served as experimental parameters. In this way, the effects of both spatial and temporal

transients of pattern speed on human tracking performance were studied. To avoid anticipation

by the subject, the amplitude and the frequency of the target pattern speed changed

pseudorandomly. The accuracy with which the subject performed the matching task was

influenced by the mean pattern speed and the parameters of the visual field. Within lower

velocity ranges, the subject's sensitivity to the instantaneous speed differences varied

according to Weber's law. The cross-correlation of the velocity time courses decreased when

the mean speed of the target pattern was increased. Two stimulus parameters had a strong

influence on the modulation of the correlation value: (1) the angular size of the stimulus on the

retina and (2) the retinal eccentricity of the stimulus.



Wust, R. M., A. M. L. Kappers, et al. (1993). “Visuomotor Control of the Relative Movement of

Random-Dot Patterns.” Perceptual and Motor Skills 77(1): 275-298.

A series of experiments were made on human performance in controlling optical relative

movement. The aim was to test the influence of different kinds of relative movement on

visually controlled steering tasks. Within adjacent displays on a computer screen random dot

patterns moved in a fixed direction at continually changing speeds (Exp. 1) or at constant

speed and in continually changing directions (Exp. 2). The subject was required to compensate

for the unpredictable modulations of the pattern movement by means of an isometric joystick.

The task was to adjust relative movements involving pure translation, symmetric convergence,

divergence, or shear. Analysis indicated that the task performance was not dependent on the

special kind of relative movement. However, performance was significantly higher in tasks

where directionally disturbed relative movement had to be controlled compared to those

situations in which relative movement varied with respect to speed.



Wylie, D. R., T. Kripalani, et al. (1993). “Responses of Pigeon Vestibulocerebellar Neurons to

Optokinetic Stimulation .1. Functional-Organization of Neurons Discriminating between

Translational and Rotational Visual Flow.” Journal of Neurophysiology 70(6): 2632-2646.

1. Extracellular recordings were made from 235 neurons in the vestibulocerebellum (VbC),

including the flocculus (lateral VbC), nodulus (folium X), and ventral uvula (ventral folium

lXc,d), of the anesthetized pigeon, in response to an optokinetic stimulus.2. The optokinetic

stimuli consisted of two black and white random-dot patterns that were back-projected onto

two large tangent screens. The screens were oriented parallel to each other and placed on

either side of the bird's head. The resultant stimulus covered the central 100-degrees x 100-

degrees of each hemifield. The directional tuning characteristics of each unit were assessed by

moving the largefield stimulus in 12 different directions, 30-degrees apart. The directional

tuning curves were performed monocularly or binocularly. The binocular directional tuning

curves were performed with the direction of motion the same in both eyes (in-phase; e.g., ipsi

= upward, contra - upward) or with the direction of motion opposite in either eye (antiphase;

e.g., ipsi = upward, contra = downward).3. Mossy fiber units (n = 17) found throughout folia

IXa,b and IXc,d had monocular receptive fields and exhibited direction selectivity in response

to stimulation of either the ipsilateral (n = 12) or contralateral (n = 5) eye. None had binocular

receptive fields.4. The complex spike (CS) activity of 218 Purkinje cells in folia lXc,d and X

exhibited direction selectivity in response to the large-field visual stimulus moving in one or

both visual fields. Ninety-one percent of the cells had binocular receptive fields that could be

classified into four groups: descent neurons (n = 112) preferred upward motion in both eyes;

ascent neurons (n = 14) preferred downward motion in both eyes: roll neurons (n = 33)

preferred upward and downward motion in the ipsilateral and contralateral eyes, respectively;

and yaw neurons (n = 40) preferred forward and backward motion in the ipsilateral and

contralateral eyes, respectively. Within all groups, most neurons (70%) showed an ipsilateral

dominance.5. For most binocular neurons (91%), the maximum depth of modulation occurred

with simultaneous stimulation of both eyes, compared with monocular stimulation of the

dominant eye alone. For the translation neurons (descent and ascent), binocular in-phase

stimulation produced the maximum depth of modulation, whereas for the rotation neurons

(roll and yaw), binocular anti-phase stimulation produced the maximum depth of

modulation.6. There was a clear functional segregation of the translation and rotation neurons.

Descent and ascent neurons were found in the medial VbC (ventral uvula and nodulus),

whereas roll and yaw neurons were found in the lateral VbC (flocculus).



Wylie, D. R., S. W. Shaver, et al. (1994). “The visual response properties of neurons in the nucleus of

the basal optic root of the northern saw-whet owl (Aegolius acadicus).” Brain, Behavior and

Evolution 43(1): 15-25.

Recorded from 81 single-unit and multi-unit clusters in the nucleus of the basal optic root

(nBOR) of the northern saw-whet owl. These cells responded best to large patterns of random

dots moving either upward, downward, or nasal to temporal. When compared with previous

studies of pigeons and chickens, these findings reveal that the nBOR in all 3 avian species

have important similarities with respect to direction preference and functional

compartmentalization. Furthermore, the high proportion of binocular neurons found in the

nBOR of the saw-whet owl is similar to the condition generally reported in frontal-eyed

mammals and hence may reflect adaptation. (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 462 of 887 in PsycINFO 1993-1995



Wylie, D. R., S. W. Shaver, et al. (1994). “The Visual Response Properties of Neurons in the Nucleus

of the Basal Optic Root of the Northern Saw-Whet Owl (Aegolius-Acadicus).” Brain Behavior

and Evolution 43(1): 15-25.

The nucleus of the basal optic root (nBOR) in birds is a component of the accessory optic

system (AOS) which is involved in the analysis of visual flowfields normally resulting from

self-motion. Using standard extracellular techniques, we recorded from 81 single-unit and

multi-unit clusters in the nBOR of the northern saw-whet owl, Aegolius acadicus, an avian

species that has a visual system with frontal emphasis. These cells responded best to large

patterns of random dots moving either upward (52%), downward (31%) or nasal to temporal

(N-T; contralateral Visual field; 15%). Only 2 units (2%) preferred temporal to nasal motion.

'Up' units were found in the dorsal portion of the nucleus whereas 'Down' units were located

more ventrally. The N-T units were found in both the lateral margin of the nucleus and ventral

to the Down units in the lateral half of the nucleus. About half of the units tested (10/19)

responded to stimulation of the ipsilateral as well as the contralateral eye. For all but one cell,

the direction preference of both eyes was the same in visual space. When compared with

previous studies of pigeons (Columba livia) and chickens (Gallus domesticus), these findings

reveal that the nBOR in ah three avian species have important similarities with respect to

direction preference and functional compartmentalization. Furthermore, the high proportion of

binocular neurons found in the nBOR of the saw-whet owl is similar to the condition generally

reported in frontal eyed mammals and hence may reflect adaptation.



Xiao, Q., P. Cao, et al. (2001). “Visual responses of neurons in the pretectal nucleus lentiformis

mesencephali to moving patterns within and beyond receptive fields in pigeons.” Brain

Behavior and Evolution 57(2): 80-86.

Large-field patterns are effective stimuli for eliciting visual responses from neurons in the

pretectal nucleus lentiformis mesencephali of nonmammals. The present study shows that

stimulation beyond the receptive field does not contribute to the visual responses of neurons in

the nucleus lentiformis mesencephali in two respects. First, changes in the direction and

velocity of motion beyond the receptive field did not affect the visual responses of the

pretectal cells to motion within the receptive field. Second, time differences in the onset of

stimulation within and outside the receptive field did not influence the visual responses of the

pretectal cells to motion in the receptive field, implying that there may be no long-range

interaction between the receptive field and its surrounding field. The present study also

indicates that the pretectal cells are not only sensitive to the direction and velocity of motion,

but also to the size and density of dots in a random-dot pattern moving through the receptive

field. Taken together with previous studies, these results suggest that the receptive field of the

pretectal cells within the nucleus lentiformis mesencephali is large in size but well defined in

boundaries, and that the pretectal cells respond to motion of visual stimuli within but not

beyond their receptive fields. Copyright (C) 2001 S. Karger AG. Basel.

Xiao, Q., P. Cao, et al. (2001). “Visual responses of neurons in the pretectal nucleus lentiformis

mesencephali to moving patterns within and beyond receptive fields in pigeons.” Brain,

Behavior and Evolution 57(2): 80-86.

Examined what effects the surrounding region of a receptive field could exert on visual

responses evoked by motion in the receptive field, and what features of a random-dot pattern

could affect the visual responses of neurons within the nucleus lentiformis mesencephali of 34

pigeons. Results show that stimulation beyond the receptive field does not contribute to the

visual responses of neurons in the nucleus lentiformis mesencephali (nLM) in 2 respects. First,

changes in the direction and velocity of motion beyond the receptive field did not affect the

visual responses of the pretectal cells to motion within the receptive field. Second, time

differences in the onset of stimulation within and outside the receptive field did not influence

the visual responses of the pretectal cells to motion in the receptive field. It is also indicated

that the pretectal cells are not only sensitive to the direction and velocity of motion, but also to

the size and density of dots in a random-dot pattern moving through the receptive field. It is

suggested that the receptive field of the pretectal cells within the nLM is large in size but well

defined in boundaries, and that the pretectal cells respond to motion of visual stimuli within

but not beyond their receptive fields. (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 99 of 887 in PsycINFO 2001 Part A



Xing, J. and G. L. Gerstein (1996). “Networks with lateral connectivity .2. Development of neuronal

grouping and corresponding receptive field changes.” Journal of Neurophysiology 75(1): 200-

216.

1. Using a three-layered network model defined in the previous paper, we studied the basic

features of neurons in the cortical layer while the synaptic strengths of lateral excitatory

connections were made modifiable by a Hebbian learning rule and a normalization process.2.

We found that neurons in the cortical layer formed groups through their lateral excitatory

connections after the network was trained with sequential random dot stimulations. Neurons

within a group connected tightly; neurons in different groups connected weakly.3. The effects

of model parameters and input parameters on the formation of neuronal groups were

investigated. Results showed that the average size and rough shapes of groups were mainly

determined by the spatial distribution of lateral connections within the cortical layer,

irrespective of input parameters and training methods. Thus groups are structure dependent.4.

Lateral inhibition in the network is the only key factor that affects the grouping of neurons.

Without an appropriate amount of distant inhibition, group formation does not occur. Group

formation is very robust to all other parameters we tested. On the other hand, group locations

are very easily disturbed by inputs or changes of parameters, suggesting that such neuronal

groups are dynamically maintained.5. With the development of neuronal groups, neurons can

be divided into two response types. TN-I neurons respond weakly to inputs and have small

receptive fields or do not respond at all (silent); TN-II neurons, similar to 30-40% of all,

respond strongly to inputs and have large receptive fields. The two types of neurons also differ

with respect to response threshold and temporal firing patterns. After groups formed, receptive

fields of TN-II neurons within the same group clustered spatially with high overlap, whereas

receptive fields of TN-I neurons with detectable responses shifted systematically with the

neuron's spatial location.6. The two types of neurons are homogeneously distributed across the

cortical layer. The population of each type of neuron produces a full representation of the

input layer with weak or strong responses, respectively.7. We concluded that neurons in the

cortical network naturally assembled into functional groups. Such groups are dynamic and

amenable to change by input stimuli. A fraction of neurons (30-40%) within the same group

shares a similar receptive field and strongly respond together to stimuli, so that the network

has more robust response to inputs. On the other hand, the responses of a large portion (60-

70%) of neurons become weak or silent: these neurons are available for other (unknown)

functional purposes.



Xing, J. and G. L. Gerstein (1996). “Networks with lateral connectivity. II. Development of neuronal

grouping and corresponding receptive field changes.” Journal of Neurophysiology 75(1): 200-

216.

Used the spiking neural network model with lateral connectivity to study the basic features of

neurons in the cortical layer while the synaptic strengths of lateral excitatory connections were

made modifiable by a Hebbian learning rule and a normalization process. Neurons in the

cortical layer formed groups through their lateral excitatory connections after the network was

trained with sequential random dot stimulations. Neurons within a group connected tightly;

neurons in different groups connected weakly. The effects of model parameters and input

parameters on the formation of neuronal groups were investigated. Results showed that the

average size and rough shapes of groups were mainly determined by the spatial distribution of

lateral connections within the cortical layer, irrespective of input parameters and training

methods. Thus groups are structure dependent. It is concluded that neurons in the cortical

network naturally assembled into functional groups. Such groups are dynamic and amenable

to change by input stimuli. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 346 of 887 in PsycINFO 1996-1997



Xu, X. M., C. E. Collins, et al. (2004). “Optical imaging of visually evoked responses in prosimian

primates reveals conserved features of the middle temporal visual area.” Proceedings of the

National Academy of Sciences of the United States of America 101(8): 2566-2571.

Optical imaging of intrinsic cortical responses to visual stimuli was used to characterize the

organization of the middle temporal visual area (MT) of a prosimian primate, the bush baby

(Otolemur garnetti). Stimulation with moving gratings revealed a patchwork of oval-like

domains in MT. These orientation domains could, in turn, be subdivided into zones selective

to directional movements that were mainly orthogonal to the preferred orientation. Similar, but

not identical, zones were activated by movements of random dots in the preferred direction.

Orientation domains shifted in preference systematically either around a center to form

pinwheels or as gradual linear shifts. Stimuli presented in different portions of the visual field

demonstrated a global representation of visual space in MT. As optical imaging has revealed

similar features in MT of New World monkeys, MT appears to have retained these basic

features of organization for at least the 60 million years since the divergence of prosimian and

simian primates.



Xue, J., D. Cai, et al. (1991). “The difference of perception times on stereopsis and form vision

between normal and amblyopic subjects.” Acta Psychologica Sinica 23(3): 279-284.

Studied visual characteristics of amblyopia in a test of perception time (PT) on stereopsis and

form vision, using a random dot stereogram (RDS). Three of the Ss had normal vision, 2 were

cured of previous amblyopia, and 3 had anisometropia or ametropia. The Stereoscopic Test

Charts (S. Yan and Z. Zheng, 1985), which consisted of red-green RDSs with 0-disparity (20-

320 sec arcs), crossed disparity (18-60 min arcs), and uncrossed disparity (12-60 min arcs),

was used. Ss were tested on different days 3-6 times. PT was studied under different chart

presentation times. Ss' PT of form and PT of stereopsis were compared among the 3 S groups.

(English abstract) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 496

of 887 in PsycINFO 1990-1992



Yajima, T., H. Ujike, et al. (1998). “Apparent depth with retinal image motion of expansion and

contraction yoked to head movement.” Perception 27(8): 937-949.

The two main questions addressed in this study were (a) what effect does yoking the relative

expansion and contraction (EC) of retinal images to forward and backward head movements

have on the resultant magnitude and stability of perceived depth, and (b) how does this

relative EC image motion interact with the depth cues of motion parallax? Relative EC image

motion was produced by moving a small CCD camera toward and away from the stimulus,

two random-dot surfaces separated in depth, in synchrony with the observers' forward and

backward head movements. Observers viewed the stimuli monocularly, on a helmet-mounted

display, while moving their heads at various velocities, including zero velocity. The results

showed that (a) the magnitude of perceived depth was smaller with smaller head velocities

(<10 cm s(-1)), including the zero-head-velocity condition, than with a larger velocity (10 cm

s(-1)), and (b) perceived depth, when motion parallax and the EC image motion cues were

simultaneously presented, is equal to the greater of the two possible perceived depths

produced from either of these two cues alone. The results suggested the role of nonvisual

information of self-motion on perceiving depth.



Yakimoff, N., P. Lansky, et al. (1988). “Systematic error in estimating the orientation of random dot

patterns.” Activitas Nervosa Superior 30(4): 275-276.

A systematic deviation in 10 Ss' estimations of orientation of dot patterns toward visual

meridia provided evidence for at least 2 visual axes, other than horizontal and vertical, that

might be accepted as standards for obliqueness. (PsycINFO Database Record (c) 2002 APA,

all rights reserved) Record 592 of 887 in PsycINFO 1988-1989



Yakimoff, N., P. Lansky, et al. (1988). “Systematic-Error in Estimating the Orientation of Random Dot

Patterns.” Activitas Nervosa Superior 30(4): 275-276.



Yakimoff, N., I. Mates, et al. (1989). “Modification of Perceived Global Orientation by Local

Orientation Cues in Random-Dot Patterns.” Perception 18(4): 523-523.



Yakimoff, N. and L. Mitrani (1979). “A concept of perceived orientation.” Perception and

Psychophysics 26(4): 327-330.

50 25-45 yr old Ss adjusted a line in a visual display to match the perceived orientation of 5

stimuli consisting of dots randomly placed in an elliptical pattern. The observed orientation

matched the line for which the sum of the squared distances of each point from the line was

minimal. (3 ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 784

of 887 in PsycINFO 1978-1984



Yakushijin, R. and A. Ishiguchi (1996). “Processing of asymmetrical noise in two- and three-

dimensional global symmetry.” Japanese Journal of Psychology 66(6): 409-417.

Studied how the visual system processes asymmetrical noise in globally symmetrical patterns

and how much noise the visual system needs to distinguish between perfectly symmetrical and

imperfectly symmetrical patterns. Human Ss: Four normal Japanese adults (graduate students).

Two experienced and 2 inexperienced Ss were asked to detect 2-dimensional and 3-

dimensional mirror symmetry in random dot displays. The use of parallel processing vs serial

processing was analyzed. (English abstract) (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 348 of 887 in PsycINFO 1996-1997



Yakushijin, R. and A. Ishiguchi (1999). “The effect of a noise plane on discrimination of mirror

symmetry in a different depth plane.” Journal of Experimental Psychology-Human Perception

and Performance 25(1): 162-173.

Participants were asked to discriminate between 100% and 50% symmetrical dot patterns (the

target plane), both of which were overlaid in depth by a random-dot plane (the noise plane).

The results showed that noise in the different depth plane was effectively excluded when the

relative binocular disparities between 2 planes were large (8' or more), the target plane was

presented in front of the noise plane, and the stimulus duration was long. A simple model

based on a grouping process in depth and on a masking effect was applied to the data. The

results of application of the model suggest that the visual system uses the output of the

grouping process to discriminate 2-dimensional symmetry in 3-D noise.



Yamada, I. and K. Tanaka (1988). “Random-Dot Model in the Presence of Signal.” Japanese Journal of

Applied Physics Part 1-Regular Papers Short Notes & Review Papers 27(2): 328-331.



Yamada, I. and K. Tanaka (1994). “Detectability in Nuclear-Medicine Images by a Random-Dot Model

- a Theoretical-Analysis.” Applied Optics 33(14): 2900-2908.

The signal-containing random-dot model is applied to an evaluation of theoretical

detectabilities of computer-generated random-dot pattern images that are idealized nuclear-

medicine images. Theoretical detectabilities, which can be obtained by a signal-containing

random-dot model, are calculated for two simulated observation procedures of these patterns.

One simulates the observation procedure in which the observer compares the transmittance at

a center of the signal and the transmittance at a background-noise region far away from the

signal. The other simulates the observation procedure in which the observer notices the

transmittance difference across the boundary between the signal and the background noise.

The theoretical detectability is compared with the result of the receiver operating

characteristics analysis. The results of receiver operating characteristics analysis are in good

agreement with the theoretical detectability obtained by the observation procedure in which

the observer notices the transmittance difference across the boundary between the signal and

the background noise.



Yanagi, J. and T. Sato (1999). “Speed perception of the motion-defined motion.” Japanese Journal of

Psychonomic Science 18(1): 95-96.

Examined speed perception from movements of motion-defined boundaries. When random

dots within target area had motion relative to its boundary motion in addition to the absolute

movement of the target itself, speed perception of the drifting target was overestimated if its

scroll direction was the same as the drift. This overestimation of speed was enhanced when

background moved oppositely to the drift of target. Such enhancement is not predicted if the

overestimation of speed is caused by "motion capture," where the boundary-defining motion

captures the motion-defined boundary. Contribution of motion-contrast detectors seems

appropriate for the cause of overestimation of speed of the motion-defined boundary.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 203 of 887 in

PsycINFO 1999



Yang, D. S., E. J. Fitzgibbon, et al. (1999). “Short-latency vergence eye movements induced by radial

optic flow in humans: Dependence on ambient vergence level.” Journal of Neurophysiology

81(2): 945-949.

Radial patterns of optic flow, such as those experienced by moving observers who look in the

direction of heading, evoke vergence eye movements at short latency. We have investigated

the dependence of these responses on the ambient vergence level. Human subjects faced a

large tangent screen onto which two identical random-dot patterns were back-projected. A

system of crossed polarizers ensured that each eye saw only one of the patterns, with mirror

galvanometers to control the horizontal positions of the images and hence the vergence angle

between the two eyes. After converging the subject's eyes at one of several distances ranging

from 16.7 cm to infinity, both patterns were replaced with new ones (using a system of

shutters and two additional projectors) so as to simulate the radial flow associated with a

sudden 4% change in viewing distance with the focus of expansion/contraction imaged in or

very near both foveas. Radial-flow steps induced transient vergence at latencies of 80-100 ms,

expansions causing increases in convergence and contractions the converse. Based on the

change in vergence 90-140 ms after the onset of the steps, responses were proportional to the

preexisting vergence angle (and hence would be expected to be inversely proportional to

viewing distance under normal conditions). We suggest that this property assists the observer

who wants to fixate ahead while passing through a visually cluttered area (e.g., a forest) and so

wants to avoid making vergence responses to the optic flow created by the nearby objects in

the periphery.



Yang, D. S., E. J. FitzGibbon, et al. (2003). “Short-latency disparity-vergence eye movements in

humans: sensitivity to simulated orthogonal tropias.” Vision Research 43(4): 431-443.

Small disparity stimuli applied to large random-dot patterns elicit machine-like vergence eye

movements at short latency. We have examined the sensitivity of these eye movements to

simulated orthogonal tropias in three normal subjects by recording (1) the effects of vertical

disparities on the initial horizontal vergence responses elicited by 2degrees crossed and

uncrossed (horizontal) disparity stimuli, and (2) the effects of horizontal disparities on the

initial vertical vergence responses elicited by 1.2degrees left-hyper and 0.8degrees right-hyper

(vertical) disparity stimuli. Initial vergence responses were strongest when the orthogonal

disparity was close to zero, and decreased to zero as the orthogonal disparity increased to

3degrees-5degrees, i.e., there was only a limited tolerance for orthogonal disparity. Tuning

curves describing the dependence of the initial change in the vergence angle on the orthogonal

disparity were well fit by a Gaussian function. An additional subject, who had an esotropia of

similar to10degrees in our experimental setup, showed almost no horizontal vergence

responses but did show vertical vergence responses to vertical disparity stimuli at short latency

(albeit slightly longer than normal) despite the fact that her esotropia resulted in uncrossed

disparities that would have totally disabled the vertical vergence mechanism of a normal

subject, cf., anomalous retinal correspondence. Published by Elsevier Science Ltd.



Yang, D. S. and F. A. Miles (2003). “Short-latency ocular following in humans is dependent on

absolute (rather than relative) binocular disparity.” Vision Research 43(12): 1387-1396.

A previous study showed that the initial ocular following responses elicited by sudden motion

of a large random-dot pattern were only modestly attenuated when that whole pattern was

shifted out of the plane of fixation by altering its horizontal binocular disparity, but the same

disparity applied to a restricted region of the dots had a much more powerful effect [Vision

Research 41 (2001) 3371]. Thus, if the dots were partitioned into horizontal bands, for

example, and alternate bands were moved in opposite directions to the left or right then ocular

following was very weak, but if the (conditioning) dots moving in one direction were all

shifted out of the plane of fixation (by applying horizontal disparity to them) then strong

ocular following was now seen in the direction of motion of the (test) dots in the plane of

fixation, i.e., moving images became much less effective when they were given binocular

disparity. We sought to determine if the greater impact of disparity with the partitioned images

was because there were additional relative disparity cues. We used a similar partitioned

display and found that the dependence of ocular following on the absolute disparity of the

conditioning stimulus had a Gaussian form with an x-offset that was close to zero disparity

and, importantly, this offset was almost unaffected by changing the absolute disparity of the

test stimulus. We conclude from this that it is the absolute-rather than the relative-disparity

that is important, and that ocular following has a strong preference for moving images whose

absolute disparities are close to zero. This is consistent with the idea that ocular following

selectively stabilizes the retinal images of objects in and around the plane of fixation and

works in harmony with disparity vergence, which uses absolute disparity to bring objects of

interest into the plane of fixation [Archives of Ophthalmology 55 (1956) 848]. (C) 2003

Elsevier Science Ltd. All rights reserved.



Yang, Y. (1995). Characteristics of spatial frequency tuning and spatial frequency channels in

stereopsis and motion.

Early stages of visual processing analyze the visual scene at multiple spatial scales. This

dissertation investigated the characteristics of spatial frequency selectivity embodied within

neural mechanisms that register global stereopsis and coherent motion. The overall sensitivity

functions for stereopsis and coherent motion detection were determined using a two-forced-

choice procedure. A masking paradigm was employed to determine the spatial frequency

selectivity of channels underlying human stereopsis and coherent motion. In the masking

experiment for stereopsis, observers viewed spatially filtered (0.4 octave bandwidth) random-

dot stereograms with noise added to one half-image. A staircase procedure measured the noise

energy at which observers could judge the location-top vs. bottom-of the depth surface on

71% of trials. In the motion masking experiment, observers viewed spatially filtered (0.4

octave bandwidth) random-dot cinematograms, with noise added to each frame image. A 2IFC

procedure measured the noise energy at which observers judged coherent motion from random

motion on 75% of trials. The overall sensitivity for stereopsis peaked at 5 c/deg and was

dependent on spatial frequency, bandwidth, size, and duration. The overall sensitivity for

coherent motion peaked at 3.7 c/deg. At higher and lower spatial frequencies, both

stereoscopic and coherent motion sensitivities were reduced. Statistical analyses showed that

the stereoscopic masking tuning functions could be grouped into two sets, one with peak

sensitivity at 3 c/deg and the other at 5 c/deg. For coherent motion, however, only one broadly

tuned channel peaking at 3.7 c/deg was observed. These results imply that the spatial

frequency selectivity of stereopsis and coherent motion differ from the tuning of spatial

frequency channels underlying form vision and local motion perception. Some MT neurons

that respond linearly to the strength of coherent motion or that are spatial frequency non-

selective may (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 396 of

887 in PsycINFO 1993-1995



Yang, Y. and R. Blake (1991). “Spatial frequency tuning of human stereopsis.” Vision Research 31(7-

8): 1177-1189.

Used a masking paradigm to measure the spatial frequency (SF) selectivity of channels

underlying human stereopsis. Two observers viewed spatially filtered random-dot stereograms

(RDSs) in which a disparate bar appeared in the top or bottom half of the display.

Superimposed on 1 RDS half image was a noise target whose SF content was varied relative

to that of the RDS. A staircase procedure was used to measure monocular noise energy (and

hence the signal-to-noise ratio) at which Ss could judge the location of the disparate bar. The

resulting stereoscopic masking functions could be grouped into 2 sets: one with peak

sensitivity at 3 c/deg and the other with peak sensitivity at 5 c/deg. Results show that a limited

number of SF-tuned mechanisms are involved in human stereopsis. Results are inconsistent

with models of stereopsis in which the disparity range to which a channel is sensitive varies

with that channel's peak SF. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 537 of 887 in PsycINFO 1990-1992

Yang, Y. and R. Blake (1991). “Spatial-Frequency Tuning of Human Stereopsis.” Vision Research

31(7-8): 1177-1189.

A masking paradigm was employed to measure the spatial frequency selectivity of channels

underlying human stereopsis. Observers viewed spatially filtered (0.4 octave bandwidth)

random-dot stereograms in which a disparate bar appeared in either the top or bottom half of

the display; superimposed on one RDS half-image was a noise target whose spatial frequency

content was varied relative to that of the RDS. A staircase procedure was used to measure the

monocular noise energy (and hence the signal-to-noise ratio) at which observers could judge

the location of the disparate bar on 71% of trials. Statistical analyses showed that the resulting

stereoscopic masking functions could be grouped into two sets, one with peak sensitivity at 3

c/deg and the other with peak sensitivity at 5 c/deg. These two channels were observed for

both crossed and uncrossed disparities ranging from coarse to fine. Essentially the same

results were obtained with binocular noise and with stereo displays flashed too briefly to be

affected by eye movements. Our results are inconsistent with models of stereopsis in which

the disparity range to which a channel is sensitive varies with that channel's peak spatial

frequency. These data imply that the spatial frequency selectivity of stereopsis differs from the

tuning of spatial channels underlying the detection and discrimination of form.



Yang, Y. and R. Blake (1995). “On the accuracy of surface reconstruction from disparity

interpolation.” Vision Research 35(7): 949-960.

Explored the accuracy with which a stereoscopically defined surface is represented when that

representation requires disparity interpolation. Two observers (one of the authors and an

undergraduate) viewed flashed random-dot stereograms depicting a pair of long, narrow,

curved ribbons of textured surface defined by a Gabor function in disparity. Observers judged

the location of the peak of the depth profile of one ribbon relative to that of the other. In one

ribbon, disparity changed smoothly while in the other, disparity was periodically sampled. Up

to a limiting sampling period, disparity interpolation produced accurate surface reconstruction,

but beyond that, performance deteriorated rapidly. This interpolation limit depended on

surface orientation (vertical vs horizontal) and disparity sign, but not Gabor spatial frequency.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 402 of 887 in

PsycINFO 1993-1995



Yang, Y., D. Rose, et al. (1992). “On the variety of percepts associated with dichoptic viewing of

dissimilar monocular stimuli.” Perception 21(1): 47-62.

Documents the stimulus conditions favoring various perceptual states. Data were obtained

from 2 Ss who observed vertical and horizontal cosine gratings and random-dot texture

patterns. Exclusive monocular dominance occurs most often when the 2 eyes view dissimilar

patterns with the same spatial-frequency content, particularly when both patterns consist of

low spatial frequencies. Superimposition also occurs most often when the 2 eyes view the

same spatial frequencies, but predominantly when those spatial frequencies are high.

Transparency is favored when the spatial-frequency difference between the eyes is great,

particularly when the view of 1 eye consists of high spatial-frequency information. (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 504 of 887 in PsycINFO 1990-

1992



Yang, Y., C. Sun, et al. (1997). “The effect of moderately increased CO-sub(2 ) concentration on

perception of coherent motion.” Aviation, Space, and Environmental Medicine 68(3): 187-

191.

Examined whether motion perception is impaired by moderately increased CO-sub(2), since

the V1 area is a gateway for visual motion information processing. The authors investigated

the effect of 2.5% CO-sub(2 ) concentration in air on the coherent motion perception of 3 Ss.

Random dot cinematograms were generated by a computer and served as visual stimuli. A

whole-room indirect calorimeter was used for the accurate measurement and control of CO-

sub(2 ) concentration in air, and served as the experimental environment. A two-interval

forced choice psychophysical procedure was employed to obtain psychometric functions. For

all 3 Ss, psychometric functions were shifted to the right when exposed to 2.5% CO-sub(2 ) in

breathing air, compared to those using fresh air. Results indicate that human ability in

detecting coherent motion can be temporally impaired when CO-sub(2 ) concentration in air is

raised to 2.5%. (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 287 of

887 in PsycINFO 1996-1997

Yang, Y. D. and R. Blake (1995). “On the Accuracy of Surface Reconstruction from Disparity

Interpolation.” Vision Research 35(7): 949-960.

Observers viewed flashed random-dot stereograms depicting a pair of long, narrow, curved

ribbons of textured surface defined by a Gabor function in disparity. Observers judged the

location of the peak of the depth profile of one ribbon relative to that of the other. In one

ribbon, disparity changed smoothly while in the other disparity was periodically sampled. Up

to a limiting sampling period, disparity interpolation produced accurate surface reconstruction,

but beyond that performance deteriorated rapidly. This interpolation limit depended on surface

orientation (vertical vs horizontal) and disparity sign, but not Gabor spatial frequency.



Yang, Y. D., C. N. Sun, et al. (1997). “The effect of moderately increased CO2 concentration on

perception of coherent motion.” Aviation Space and Environmental Medicine 68(3): 187-191.

Background: Several studies have shown that some aspects of vision are impaired when

exposed to higher than normal CO2 concentrations in air. The effect of moderately increased

CO2 concentration on coherent motion perception, however, has not been studied. Hypothesis:

Studies in neurophysiology and cell biology have provided evidence that higher than normal

CO2 concentration in air affects cell activities from the retina to the cortex, including the V1

area in the visual cortex. We predicted that motion perception may be impaired by moderately

increased CO2, since the V1 area is a gateway for visual motion information processing. The

purpose of the present work was to investigate the effect of 2.5% CO2 concentration in air on

coherent motion perception. Methods: Random dot cinematograms were generated by a

computer and served as visual stimuli. A whole-room indirect calorimeter was used for the

accurate measurement and control of CO2 concentration in air, and served as the experimental

environment. A two-interval-forced choice (2IFC) psychophysical procedure was employed to

obtain psychometric functions. Results: For all three subjects, psychometric functions were

shifted to the right when exposed to 2.5% CO2 in breathing air, compared to those using fresh

air. Conclusion: This finding implies that human ability in detecting coherent motion can be

temporally impaired when CO2 concentration in air is raised to 2.5%.



Yao, G. (1992). “Experimental research on stereoscopic plasticity.” Acta Psychologica Sinica 24(2):

142-147.

Studied human stereopsis, the relationship among the scale, position, and structure of a figure,

and the texture of an image. Ss were 4 normal Chinese adults (normal stereopsis) with

previous experience in observing sets of random-dot stereograms. Ss were tested using 13

figures designed via C. M. Aschenbrenner's method (1954), in which the figures were placed

in 4 sets (Set 1 of different sizes, Set 2 of different shapes, Set 3 of different dimensions, and

Set 4 of different textures). The plasticity of a set of random-dot stereograms associated with

large distributed figures, large disparities, complex configurations, and gauze-like patterns are

discussed. (English abstract) (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Record 497 of 887 in PsycINFO 1990-1992



Yellott, J. I. and J. L. Kaiwi (1979). “Depth inversion despite stereopsis: The appearance of random-dot

stereograms on surfaces seen in reverse perspective.” Perception 8(2): 135-142.

Inside-out relief masks of faces can be depth-inverted (i.e., seen in reverse perspective) during

close-up binocular viewing. If a random-dot stereogram is projected onto such a mask,

stereopsis can be achieved for the stereogram, and its depth planes are correctly seen while the

mask itself, including the region covered by the stereogram, is simultaneously perceived as

depth-inverted. The present paper shows that binocular depth inversion cannot be explained by

a complete loss of stereoscopic information (e.g., through monocular suppression), or by a

process analogous to pseudoscopic viewing whereby retinal disparities are incorporated into

perception but with their signs uniformly reversed. (11 ref) (PsycINFO Database Record (c)

2002 APA, all rights reserved) Record 791 of 887 in PsycINFO 1978-1984



Yonas, A., L. G. Craton, et al. (1987). “Relative motion: Kinetic information for the order of depth at

an edge.” Perception and Psychophysics 41(1): 53-59.

Studied the sensitivity of 16 students enrolled at the University of Minnesota to the relative

motion of texture and contour as information for depth at an edge. The relationship between

the motion of optical texture, indicating a surface, and the motion of a contour, indicating an

edge, determines whether the surface is perceived as occluding or occluded. A 1-way analysis

of variance (ANOVA) was carried out on the mean number of "no depth" responses for 8

conditions. Ss viewed computer-generated random-dot displays in which this relative-motion

information provided the only information for depth order and a 2nd type of display in which

order in depth was specified both by relative-motion information and by the accretion and

deletion of texture. Reliable depth effects were obtained under both conditions. (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 635 of 887 in PsycINFO 1985-

1987



Yu, B. l., J. Brogan, et al. (1985). “The detection of Chinese strokes and characters in visual noise.”

Perception and Psychophysics 38(1): 23-29.

Investigated the effects of experience, method, and stimulus form on the detectability of dotted

approximations to Chinese strokes and characters when they are masked by random-dot visual

noise. Ss were 3 undergraduates with no previous exposure to Chinese pictographic

calligraphy and 3 students who had been reading and writing Chinese pictographs throughout

their lives. Results of 2 experiments show that experience effects were limited. Even when

small effects were present, they were in the direction opposite to that predicted. Similarly,

method (static or dynamic) played only a minor role in determining performance. However,

strong stimulus-form effects existed that were well predicted by a previously developed

autocorrectional-type computational model of the dotted form detection process. This model is

passive, automatic, and preattentive. (5 ref) (PsycINFO Database Record (c) 2002 APA, all

rights reserved) Record 667 of 887 in PsycINFO 1985-1987



Yuan, H. F., W. L. Sachtler, et al. (2000). “Effects of time delay on depth perception via head-motion

parallax in virtual environment systems.” Presence-Teleoperators and Virtual Environments

9(6): 638-647.

Experiments were conducted to determine how the ability to detect and discriminate head-

motion parallax depth cues is degraded by time delays between head movement and image

update. The stimuli consisted of random-dot patterns that were programmed to appear as one

cycle of a sinusoidal grating when the subject's head moved. The results show that time delay

between head movement and image update has essentially no effect on the ability to

discriminate between two such gratings with different depth characteristics when the delay is

less than or equal to roughly 265 ms.



Yuan, J. C. and S. J. Huang (1996). “Do 2D grating plaids use the same processing channel as 3D

random dots plaids?” Investigative Ophthalmology & Visual Science 37(3): 3373-3373.



Yuille, A. L. and N. M. Grzywacz (1998). A theoretical framework for visual motion. High-level

motion processing: Computational, neurobiological, and psychophysical perspectives. T.

Watanabe. Cambridge, MA, The MIT Press: 187-211.

The authors attempt to classify the most important visual motion phenomena. They then

describe a theoretical framework that appears to be sufficiently rich to account for most

existing psychophysical and physiological experiments. Specific models (parts of the

framework which have been developed in detail) are shown to be in detailed agreement with

experiments. Finally the chapter discusses experimental and computational problems, which

must be solved as a theory of motion measurement is developed.



Zahn, C. (1971). “Graph-Theoretical methods for Detecting and Describing Gestalt Structures.” IEEE

TRANSACTIONS ON SYSTEMS, MAN, AND CYBERNETICS. 20(1): 68-86.

A family of gragh-theoretical algorithms based on the minimal spanning tree are capable of

detecting several kinds of cluster structure in arbitrary point sets; description of the detected

clusters is possible in some cases by extensions of the method.



Zaksas, D., J. W. Bisley, et al. (2001). “Motion information is spatially localized in a visual working-

memory task.” Journal of Neurophysiology 86(2): 912-921.

We asked if the information about stimulus motion used in a visual working-memory task is

localized in space. Monkeys compared the directions of two moving random-dot stimuli,

sample and test, separated by a temporal delay and reported whether the stimuli moved in the

same or in different directions. By presenting the two comparison stimuli in separate locations

in the visual field, we determined whether information about stimulus direction was spatially

localized during the storage and retrieval/comparison components of the task. Two

psychophysical measures of direction discrimination provided nearly identical estimates of the

critical spatial separation between sample and test stimuli that lead to a loss in threshold.

Direction range thresholds measured with dot stimuli consisting of a range of local directional

vectors were affected by spatial separation when a random-motion mask was introduced

during the delay into the location of the upcoming test. The selective masking at the test

location suggests that the information about the remembered direction was localized and

available at that location. Direction difference thresholds, measured with coherently moving

random dots, were also affected by separation between the two comparison stimuli. The

separation at which performance was affected in both tasks increased with retinal eccentricity

in parallel with the increase in receptive-field size in neurons in cortical area MT. The loss

with transfer of visual information between different spatial locations suggests a contribution

of cortical areas with localized receptive fields to the performance of the memory task. The

similarity in the spatial scale of the storage mechanism derived psychophysically and the

receptive field size of neurons in area MT suggest that MT neurons are central to this task.



Zanker, J. (1994). “Modeling Human Motion Perception .1. Classical Stimuli.” Naturwissenschaften

81(4): 156-163.

Motion perception is one of the most prominent tasks of the visual system and therefore has

been extensively investigated both experimentally and theoretically. A classical model

describing the mechanism of motion detection originally developed in the context of insect

orientation behavior, the elementary motion detector (EMD) of the correlation type, turned out

to be very powerful in explaining many basic aspects of human motion perception. For more

complex visual tasks, like the discrimination of a figure from its background by relative

motion, on the other hand, further processing of motion information is required. In the first

part of this review it will be illustrated by means of a few examples, what kind of motion

information can be derived from the mere correlation-type model, and what perceptual

phenomena can be accounted for by the EMD. In the second part, more recently developed

stimuli will be introduced to answer the question what further processing steps, or more

sophisticated mechanisms than the EMD, have to be assumed in order to understand ''higher''

aspects of human motion perception.



Zanker, J. M. (1993). “Theta motion: A paradoxical stimulus to explore higher order motion

extraction.” Vision Research 33(4): 553-569.

Investigated how motion detectors respond to 3 classes of motion stimuli realized as random-

dot kinematograms: (1) Fourier stimuli, (2) drift-balanced stimuli, and (3) theta stimuli. Two

psychophysical experiments showed that human observers perceived the direction of object

motion in all 3 classes of stimuli. Simple (i.e., single-layer) motion detectors, however, only

extracted the motion direction of the object in the case of Fourier stimuli and, if a nonlinear

preprocessing was assumed, in the case of drift-balanced stimuli. To account for the detection

of the theta motion, a model consisting of 2 hierarchical layers of motion detectors was

developed and simulated for conditions used in the psychophysical experiments. An attempt is

made to incorporate the proposed model into a general scheme of visual motion processing.

(PsycINFO Database Record (c) 2002 APA, all rights reserved) Record 489 of 887 in

PsycINFO 1993-1995



Zanker, J. M. (1993). “Theta-Motion - a Paradoxical Stimulus to Explore Higher-Order Motion

Extraction.” Vision Research 33(4): 553-569.

Apparent motion stimuli of increasing complexity have been applied to analyse the

mechanisms underlying visual motion perception. In the present paper it is investigated how

motion detectors respond to three classes of stimuli which are realized as random-dot

kinematograms. (i) In the most conventional stimuli, Fourier motion, a group of dots is

displaced coherently in a random-dot pattern. (ii) In drift-balanced motion stimuli a bar made

of static random dots is shifted in front of another random-dot pattern. (iii) In the novel class

of stimuli, theta motion, an object which is exclusively defined by dot motion into one

direction, is moving itself into the opposite direction. It is shown in psychophysical

experiments that human observers perceive the direction of object motion in all three classes

of stimuli. Simple motion detectors, however, only extract the motion direction of the object in

the case of Fourier stimuli, and in the case of drift-balanced stimuli, if a nonlinear

preprocessing is assumed. Any of the model alternatives discussed so far just detects the

moving dots but not the object in a theta-stimulus, as is illustrated by a combinatorial analysis

using a simplified version of a motion detector of the correlation type, which operates on a

discrete time scale and takes only discrete values. In order to account for the detection of

theta-motion, a model consisting of two hierarchical layers of motion detectors is developed,

and simulated for conditions as used in the psychophysical experiments. The perception of

theta-motion and the two-layer model is discussed in relation to psychophysical data and

theoretical considerations from the literature, to try to incorporate the proposed two-layer

model into a general scheme of visual motion processing.



Zanker, J. M. (1995). “Does Motion Perception Follow Weber Law.” Perception 24(4): 363-372.

The subjective strength of a percept often depends on the stimulus intensity in a nonlinear

way. Such coding is often reflected by the observation that the just-noticeable difference

between two stimulus intensities (JND) is proportional to the absolute stimulus intensity. This

behaviour, which is usually referred to as Weber's Law, can be interpreted as a compressive

nonlinearity extending the operating range of a sensory system. When the noise super-imposed

on a motion stimulus is increased along a logarithmic scale (in order to provide linear steps in

subjective difference) in motion-coherency measurements, observers often report that the

subjective differences between the various noise levels increase together with the absolute

level. This observation could indicate a deviation from Weber's Law for variation of motion

strength as obtained by changing the signal-to-noise ration in random-dot kinematograms.

Thus JNDs were measured for the superposition of uncorrelated random-dot patterns on static

random-dot patterns and three types of motion stimuli realised as random-dot kinematograms,

namely large-field and object 'Fourier' motion (all or a group of dots move coherently), 'drift-

balanced' motion (a travelling region of static dots), and paradoxical 'theta' motion (the dots on

the surface of an object move in opposite direction to the object itself). For all classes of

stimuli, the JNDs when expressed as differences in signal-to-noise ratio turned out to increase

with the signal-to-noise ratio, whereas the JNDs given as percentage of superimposed noise

appear to be similar for all tested noise levels. Thus motion perception is in accordance with

Weber's Law when the signal-to-noise ratio is regarded as stimulus intensity, which in turn

appears to be coded in a nonlinear fashion. In general the Weber fractions are very large,

indicating a poor differential sensitivity in signal-to-noise measurements.



Zanker, J. M. (1995). “Does motion perception follow Weber's Law?” Perception 24(4): 363-372.

When a noise superimposed on a motion stimulus is increased along a logarithmic scale in

motion-coherency measurements, observers often report that subjective differences between

the noise levels increase together with the absolute level. The present study examined whether

this observation indicates availability of estimates of linear-motion strength and thus a

deviation from Weber's Law for motion-coherency estimates. Ss compared test and reference

motion stimuli. Just noticeable differences (JNDs) were measured for the superposition of

uncorrelated random-dot (RD) patterns on static RD patterns and 3 types of motion stimuli

realized as RD kinematograms. JNDs expressed as differences in signal-to-noise ratio (SNR)

increased with the SNR. JNDs given as percentage of superimposed noise appeared to be

similar for all tested noise levels. Thus, motion perception is in accordance with Weber's Law

when the SNR is regarded as stimulus intensity. (PsycINFO Database Record (c) 2002 APA,

all rights reserved) Record 401 of 887 in PsycINFO 1993-1995



Zanker, J. M. (1995). Of models and men: Mechanisms of human motion perception. Early vision and

beyond. T. V. Papathomas and C. Chubb. Cambridge, MA, US, The MIT Press: 155-165.

(from the book) focuses primarily on 2nd-order motion defined by 1st-order motion / such

"theta motion" . . . is elicited, for instance, by a moving patch, defined by random texture that

is itself translating, but in a direction different from the direction of the patch / Zanker models

the detection of such motion computationally, and shows that the computations required to

detect theta motion will also detect other sorts of 2nd-order motion (from the chapter)

[showed] how highly artificial motion stimuli are used to test specific hypotheses about

mechanisms underlying human motion perception / starting from very basic apparent motion

stimuli, random-dot kinematograms of increasing complexity were introduced (Fourier, drift-

balanced, theta-motion) that challenge the perceptual capabilities, as well as our

understanding, of the visual system / on the other hand, models of motion processing were

considered that get more complex in parallel to the stimuli / addressed [2 questions] to clarify

how this approach helps to understand human brain function: (1) can the models be integrated

into some systematic order and related to physiology [and] (2) can any behavioral significance

be attributed to these mechanisms (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 390 of 887 in PsycINFO 1993-1995



Zanker, J. M. (1996). “On the elementary mechanism underlying secondary motion processing.”

Philosophical Transactions of the Royal Society of London Series B-Biological Sciences

351(1348): 1725-1736.

The movement of luminance-defined targets can be easily extracted by elementary motion

detectors (EMDs) of the correlation type which often are referred to as Reichardt-detectors. In

contrast: to such 'primary motion', in 'secondary motion' the moving target is defined by more

complex features, like changes in texture, flicker, or local contrast. Such stimulus attributes

have to be extracted from the retinal intensity distribution by some nonlinear preprocessing,

before they are fed into motion detectors. An intriguing case is the perception of the

movement of the motion signal, as is present in theta motion, where an object moves in a

different direction than the texture on its surface. A two-layer model of hierarchically

organised EMDs has been postulated to account for such motion extraction. Other than for the

first layer, the computational nature of the mechanism underlying motion processing in the

second layer so far is a matter of speculation, and is therefore characterized here by means of

computer simulations and psychophysical experiments. Random dot kinematograms were

generated in which sinusoidally modulated vertical dot motion defined gratings, and

coherence thresholds were measured for the direction discrimination of a horizontally

travelling modulation function. This was done for a variety of spatial frequencies and speeds

of the modulation sinusoid. Thresholds turn out to be lowest not for a particular speed, but for

a fixed temporal frequency of the modulation function (about 1 cycle per second), when

various combinations of fine and coarse, and fast and slow secondary gratings are tested. This

result favours a correlation-type mechanism over a gradient-type scheme which should lead to

a speed-optimum independent of spatial frequency.



Zanker, J. M. (1997). “Second-order motion perception in the peripheral visual field.” Journal of the

Optical Society of America A: Optics and Image Science 14(7): 1385-1392.

Compared effects on retinal eccentricity for 3 types of random dot kinematograms for

phimotion (object moving together with another object), mumotion ( object moving

horizontally with another object), and thetamotion (object is static with another object). Four

experienced psycophysical observers participated. The detection, orientation discrimination,

and motion direction discrimination of oblique, vertically moving bars was tested at horizontal

eccentricities between 0 deg. and 16 deg.. Bars were defined on a dynamic noise background

by an area of static dots (drift-balanced motion) or by coherent dot motion either in the

direction of the bar motion (Fourier motion) or in the orthogonal direction (thetamotion).

Coherence thresholds for direction discrimination are severely impaired in the periphery for

both types of 2nd-order motion but not for Fourier motion, whereas orientation discrimination

and detection marginally decline for all 3 bar types when the stimuli are presented further out

in the periphery. In a control experiment it is shown that this result cannot be due entirely to

the changes in spatial scale of the peripheral visual system. (PsycINFO Database Record (c)

2002 APA, all rights reserved) Record 295 of 887 in PsycINFO 1996-1997



Zanker, J. M. (1999). “Generating motion-defined gratings from spatially filtered random dot patterns.”

Investigative Ophthalmology & Visual Science 40(4): S422-S422.



Zanker, J. M. (1999). “Perceptual learning in primary and secondary motion vision.” Vision Research

39(7): 1293-1304.

Specific improvements of perceptual capabilities with practise ape thought to give some clues

about cortical plasticity and the localisation of cortical processing. In the present study,

perceptual learning is used as a paradigm to separate mechanisms underlying the perception of

different classes of motion stimuli. Primary motion stimuli (Phi-motion). are characterised by

displacements of the luminance distribution. However, for secondary motion stimuli the

movement is not accompanied by a corresponding luminance shift. Instead, moving objects

are defined by their temporal frequency composition (mu-motion) or by motion itself (theta-

motion). On theoretical grounds, the perception of secondary motion requires a higher degree

of nonlinearity in the processing stream than the perception of primary motion but debate

continues as to whether there might be a unique mechanism underlying the perception of both

motion classes. In a large group of subjects, coherence thresholds for direction discrimination

in random dot kinematograms of Phi-, mu-, and theta-motion were repeatedly measured in a

staircase paradigm. Training effects were found on different timescales, within short sessions

containing multiple staircases and over training periods of several months. They were fairly

stable over long breaks without testing. When subjects were trained with two different motion

stimuli in a sequence, an asymmetry in the transfer of perceptual learning was revealed:

sensitivity increases achieved during practise of theta-motion are largely transferred to Phi-

motion, but theta-motion perception does not profit from prior exposure to Phi-motion. This

finding supports the view derived from modelling of motion processing that there must be at

least partially separate systems. A primary motion detection mechanism falls short of

discriminating direction in secondary motion stimuli, whereas a mechanism able to extract

secondary motion will be inherently sensitive to primary motion. (C) 1999 Elsevier Science

Ltd. All rights reserved.



Zanker, J. M. and O. J. Braddick (1999). “How does noise influence the estimation of speed?” Vision

Research 39(14): 2411-2420.

Local motion signals have to be combined in space and time, to yield a coherent motion

percept as it is involved in a variety of visual tasks. This combination necessarily means to

trade-off between loosing spatio-temporal resolution by pooling local signals and maintaining

perceptually significant segmentation between them. When signals are pooled to detect the

presence of coherent motion in large amounts of random noise, the question raised is how the

noise affects the perceived quality, in particular speed, of the coherent motion. Is there an

analogy to the well-known reduction in the perceived speed of moving gratings at low

contrast? Using a two-interval forced-choice procedure, we have investigated the assessment

of speed in random-dot kinematograms containing different proportions of noise. Under the

conditions investigated, there is no strong reduction of perceived speed with increasing noise,

as long as coherence levels remain well above the thresholds for directional judgements. This

basic result, which could suggest considerable but not perfect segregation of signal and noise

motion components in the pooling process leading to speed estimation, is discussed in relation

to a model that is designed to decode speed from a population of elementary motion detectors

(EMDs) of the correlation type. A strategy to estimate speed from a set of EMDs with a

variety of spatio-temporal tuning does not only provide a velocity predictor unambiguous with

the spatial structure of the stimulus, but also is largely independent of noise. (C) 1999 Elsevier

Science Ltd. All rights reserved.



Zanker, J. M. and N. R. Burns (2001). “Interaction of first- and second-order direction in motion-

defined motion.” Journal of the Optical Society of America a-Optics Image Science and

Vision 18(9): 2321-2330.

Motion-defined motion can play a special role in the discussion of whether one or two

separate systems are required to process first- and second-order information because, in

contrast to other second-order stimuli, such as contrast-modulated contours, motion detection

cannot be explained by a simple input nonlinearity but requires preprocessing by motion

detectors. Furthermore, the perceptual quality that defines an object (motion on the object

surface) is identical to that which is attributed to the object as an emergent feature (motion of

the object), raising the question of how these two object properties are linked. The interaction

of first- and second-order information in such stimuli has been analyzed previously in a

direction-discrimination task, revealing some cooperativity. Because any comprehensive

integration of these two types of motion information should be reflected in the most

fundamental property of a moving object, i.e., the direction in which it moves, we now

investigate how motion direction is estimated in motion-defined objects. Observers had to

report the direction of moving objects that were defined by luminance contrast or in random-

dot kinematograms by differences in the spatiotemporal properties between the object region

and the random-noise background. When the dots were moving coherently with the object

(Fourier motion), direction sensitivity resembled that for luminance-defined objects, but

performance deteriorated when the dots in the object region were static (drift-balanced

motion). When the dots on the object surface were moving diagonally relative to the object

direction (theta motion), the general level of accuracy declined further, and the perceived

direction was intermediate between the veridical object motion direction and the direction of

dot motion, indicating that the first- and second-order velocity vectors are somehow pooled.

The inability to separate first- and second-order directional information suggests that the two

corresponding subsystems of motion processing are not producing independent percepts and

provides clues for possible implementations of the two-layer motion-processing network. (C)

2001 Optical Society of America.



Zanker, J. M. and I. S. Huepgens (1994). “Interaction between primary and secondary mechanisms in

human motion perception.” Vision Research 34(10): 1255-1266.

Investigated how the direction of dot motion influences the perception of object motion by

systematically varying the direction of dot motion which defines an object in a multiframe

random-dot kinetogram (RDK), from parallel through oblique to orthogonal. Ss (aged 23-34

yrs) viewed various computer-generated RDKs and responded as to the horizontal direction of

movement they perceived; noise was increased after 3 correct responses. A vertical component

was also added to the test. Results show that the characteristic shape of the tuning curve

appears to be stable against all variations in the stimulus parameters tested, namely object

shape, speed and presentation time, and the direction of object motion. (PsycINFO Database

Record (c) 2002 APA, all rights reserved) Record 435 of 887 in PsycINFO 1993-1995



Zanker, J. M. and I. S. Hupgens (1994). “Interaction between Primary and Secondary Mechanisms in

Human Motion Perception.” Vision Research 34(10): 1255-1266.

Two layers of information processing can be distinguished as being involved in human motion

perception. The primary motion detection stage processes displacements of the luminance

distribution across space, such as experienced in natural scenes during the pursuit of moving

targets. Primary motion detection is often investigated with artificial motion stimuli realized as

random-dot kinematograms (RDKs). Such stimuli belong to the class of ''Fourier motion'', and

their perception can be easily explained by means of elementary motion detectors (EMDs) of

the correlation type. Other tasks require the comparison of motion signals from neighbouring

areas in the visual field, The perception of the displacement of the motion distribution, for

instance, has been accounted for by a secondary motion processing stage. In order to

understand the principles of interaction between the motion in neighbouring areas of the visual

field, we investigated the sensitivity of the human visual system for moving objects which are

defined by moving dots in variable directions. These experiments lead to ''secondary tuning

curves'' of direction discrimination far secondary motion as function of primary motion

direction. A base level of sensitivity for all dot motion directions without a velocity

component in the same direction of the object movement is enhanced when the object and the

dots have a common velocity component. Thus primary motion in any direction can be

exploited by the secondary stage, and primary and secondary system both feed into the object

motion percept. Furthermore it is suggested from the shape of the secondary tuning curve that

the outputs from the two layers of motion processing do not superimpose linearly, but are

combined by some sort of veto-like mechanism which increases the directional sensitivity

when the two processing layers experience movement along the same direction.



Zanker, J. M. and G. Mohn (1993). “On the Development of Motion Perception in Human Infants.”

Clinical Vision Sciences 8(1): 63-71.

1. Motion perception is one of the most prominent tasks of the visual system. However,

comparatively sparse data are available about motion specific behavioural responses of human

infants.2. We studied in a preferential looking paradigm how infants between the age of 2 and

6 months respond to simple and complex motion stimuli.3. Surprisingly, these experiments

gave no clear indication of direction specific motion responses during the first 6 months of

life.4. Moving random dots were preferred to a static random-dot pattern, but not to dynamic

noise of the same temporal structure as the motion stimulus. Therefore it is not appropriate to

draw conclusions from such data on the mechanisms underlying the development of motion

perception.



Zanker, J. M. and J. D. Ryan (2000). “Misjudging the speed of random dots moving in apertures.”

Perception 29: 25-25.



Zanoni, D. and A. L. Rosenbaum (1991). “A New Method for Evaluating Distance Stereo Acuity.”

Journal of Pediatric Ophthalmology & Strabismus 28(5): 255-260.

A new standardized method for evaluating distance stereo acuity has been developed, using

the graphic capacity of a high-frequency microprocessor and liquid crystal binocular glasses.

Images are alternately presented at a frequency of 60 cycles per second to each eye, using

synchronized liquid crystal shutter glasses. The amount of disparity in the stereo patterns can

be altered to allow a measurement as refined as 15 seconds of arc ("). This instrument is now

commercially available as part of the Mentor B-Vat system.We evaluated distance Random

Dot and Contour circle stereo acuity of 50 normal subjects using this new method and

compared these results to conventional Titmus and Randot circles at near. The distance stereo

acuity mean results were 139" for the Random Dot test and 41.1" for the Contour circles. The

near stereo acuity results were 41.8" for the Titmus circles and 27" for the Randot circles.

Statistically, the Titmus results at near can be compared to the Contour circles at distance. The

distance Random Dot test results demonstrate much less stereoability than the other test. The

application of these new distance stereotests will be discussed.



Zaroff, C. M., M. Knutelska, et al. (2003). “Variation in stereoacuity: Normative description, fixation

disparity, and the roles of aging and gender.” Investigative Ophthalmology & Visual Science

44(2): 891-900.

PURPOSE. Variation in stereoacuity was examined in a large group of observers with Snellen

acuity of 20/30 or less.METHODS. Threshold retinal disparity for 2.78degrees X 2.28degrees

rectangular test stimuli was determined as a function of the retinal disparity (varied from 55

arcmin uncrossed to 55 arcmin crossed) of a 5.57degrees X 4.8degrees rectangular pedestal

stimulus in 160 observers 15 to 79 years of age. In most cases, data were collected during

viewing of random dot stereograms (RDSs) presented for 100-ms, which prevents

involvement of vergence or monocular depth cues.RESULTS. When plotted logarithmically,

100-ms thresholds in 106 observers less than 60 years of age approximated a normal

distribution (mean, 1.57 +/- 0.227 [SD] log arcsec [37 linear arcsec]). Among these, one

observer was supernormal, 88% were within the normal range ( 2 SD of the log mean), 2%

had elevated thresholds, and 8% failed testing with 100-ms stimuli but had residual binocular

depth discrimination; I observer was stereoblind. In contrast, only 37% of the observers aged

60 to 69 and 25% of the observers aged 70 to 79 had stereoacuity within the normal range.

Moreover, the extent of the stereo deficiencies became more pronounced with age. Fixation

disparity was operationally defined as optimal stereoscopic threshold with a nonzero retinal

disparity pedestal. Of the 151 normal observers tested, 89% were maximally sensitive to

disparities within 11 arcmin of fixation: all males were maximally sensitive to pedestals within

22 arcmin of fixation, whereas 8% of females had fixation disparities of more than 22 arcmin.

Males were more likely to be sensitive with uncrossed-disparity pedestals, whereas females

were more likely to be sensitive with crossed disparity.CONCLUSIONS. Age-related

deterioration in stereoacuity is reflected not only by a linear correlation between age and

threshold but also by a catastrophic factor that produces more marked deterioration after age

60. Both factors are probably cerebral and not specifically related to stereopsis. The

prevalence of fixation disparity in the normal population is probably more common than

previously reported.



Zhang, J. (1994). “Figural Segregation and Direction Discrimination in Random-Dot Kinematogram.”

Investigative Ophthalmology & Visual Science 35(4): 1666-1666.



Zhang, J. (1995). “Motion Detectors and Motion Segregation.” Spatial Vision 9(2): 261-273.

The response of motion detectors necessarily confound image velocity with image structure.

In particular, even a rigidly moving image (with a uniform velocity held) will give rise to non-

uniform detector responses. A mathematical framework has been proposed on bow to

intrinsically compare motion detectors' responses so that their differences will reflect the true

differences in image velocity (Zhang and Wu, Proc. Natl. Acad. Sci. USA 87, 7819-7823,

1990). Here, this notion of 'intrinsic differentiation' was implemented by introducing a

gamma-matrix determined by the image spatial gradients. The perceptual phenomenon of

random-dot motion segregation was successfully simulated.



Zhang, Q., M. Idesawa, et al. (1998). “Pantomime effect in the perception of volumetrical transparent

illusory object with binocular viewing.” Japanese Journal of Applied Physics Part 2-Letters

37(3B): L329-L332.

Transparency and volume perception are important issues in 3-D object perception. We report

here a new visual effect in 3-D illusory object perception with binocular viewing, named

'pantomime effect', and introduce a new framework of the effect based on three types of

'sustaining cues'. We also compare sustaining cues with occlusion cues. In addition, the

perception of transparent and volumetrical objects was verified by the experiments using

another illusory probe stimulus. It was also found that side sustaining cues played an essential

role in volume perception, and the transparency in pantomime effect was different from that in

multilayer transparent planes depicted by a random dot stereogram.



Zhang, S. W., M. V. Srinivasan, et al. (1995). “Convergent Processing in Honeybee Vision - Multiple

Channels for the Recognition of Shape.” Proceedings of the National Academy of Sciences of

the United States of America 92(7): 3029-3031.

Advanced mammalian visual systems can recognize a familiar shape under a variety of

viewing conditions. Recognition is possible whether the shape is presented in simple outline,

as a random dot stereogram, or by motion contrast. We report here that bees have a similar

ability: they can recognize a shape when it is learned through visual signals of one kind and

subsequently viewed through another. The results reveal that (i) bees that have learned a shape

defined in terms of Luminance contrast can recognize the same shape when it is defined in

terms of motion contrast, (ii) shapes that are delineated by motion contrast are discriminated

through a channel that receives input only from the green photoreceptors, (iii) a shape learned

through one class of signal is subsequently recognized via any of these other classes, and (iv)

shape is memorized in a generic form regardless of whether it is initially sensed by green-

contrast, blue-contrast, luminance-contrast, or motion-contrast signals.



Zhang, W. T. and R. x. Peng (1983). “The lateralization of hemispheric function in the recognition of

Chinese characters.” Neuropsychologia 21(6): 679-682.

Conducted 2 experiments to investigate the lateralization of hemispheric functions. In Exp I,

single Chinese characters, English words, and random dot forms were used as stimuli

presented to the left or right visual field of 12 adults. In Exp II, 12 adults and 12 9-10 yr olds

were asked to recognize single characters presented in one field and arabic numerals in the

opposite field. Adults and children all showed left-hemisphere superiority in the recognition of

characters. Some possible causes are given to explain why Chinese characters, being

components of an ideographic language, show a superiority similar to that of phonetic

languages. (19 ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record

713 of 887 in PsycINFO 1978-1984



Zheng, Z. y. and et al. (1983). “The information processing of binocular stereoscopic vision: I. The

effects of spatial filtering on stereopsis.” Acta Psychologica Sinica 15(2): 192-197.

Investigated the rule of fusion on the spatial frequency domain in binocular stereopsis. Two

sets of random-dot stereograms with different texture were optically filtered by low, high, and

band pass filters. Filtered stereograms were paired in various combinations and examined

under a stereoscope to see if any depth could be perceived. It was found that all the

stereograms that passed the same filter could produce stereopsis perfectly. Two sets with

different texture had common tendencies but in some cases gave different results. The overlap

of spatial frequency spectra between the 2 half pictures of a stereogram could not be simply

used as a rule to explain the fusing mechanism of stereo perception. (10 ref) (PsycINFO

Database Record (c) 2002 APA, all rights reserved) Record 717 of 887 in PsycINFO 1978-

1984



Zivotofsky, A. Z., K. G. Rottach, et al. (1996). “Saccades to remembered targets: The effects of smooth

pursuit and illusory stimulus motion.” Journal of Neurophysiology 76(6): 3617-3632.

Studied the effects of illusory motion of targets on the accuracy of saccades (SACs) made to

remembered locations. Authors measured the accuracy of SACs in 4 human Ss (aged 30-48

yrs) to remembered locations of targets on a random dot display that was either stationary or

moving horizontally. During the interval period between the target flash and the memory-

guided SAC, Ss either fixated a stationary spot or pursued a spot moving vertically. Results

showed that horizontal background motion, either during fixation of a stationary target or

during smooth pursuit of a vertically moving target, caused a threefold increase in the

inaccuracy of the horizontal component of memory-guided SACs. Further measures were

made to determine the level of inaccuracy of memory-guided SACs; it was found that final

eye position attained in darkness was generally closer to the required location, but it too was

inaccurate. Results are best accounted for by a model in which both the working memory of

target location and the internal representation of the horizontal eye movements were corrupted

by the illusory visual stimulus. (PsycINFO Database Record (c) 2002 APA, all rights

reserved) Record 289 of 887 in PsycINFO 1996-1997

Zivotofsky, A. Z., K. G. Rottach, et al. (1996). “Saccades to remembered targets: The effects of smooth

pursuit and illusory stimulus motion.” Journal of Neurophysiology 76(6): 3617-3632.

1. Measurements were made in four normal human subjects of the accuracy of saccades to

remembered locations of targets that were flashed on a 20 X 30 deg random dot display that

was either stationary or moving horizontally and sinusoidally at +/-9 deg at 0.3 Hz. During the

interval between the target flash and the memory-guided saccade, the ''memory period'' (1.4 s),

subjects either fixated a stationary spot or pursued a spot moving vertically sinusoidally at +/-

9 deg at 0.3 Hz.2. When saccades were made toward the location of targets previously flashed

on a stationary background as subjects fixated the stationary spot, median saccadic error was

0.93 deg horizontally and 1.1 deg vertically. These errors were greater than for saccades to

visible targets, which had median values of 0.59 deg horizontally and 0.60 deg vertically.3.

When targets were flashed as subjects smoothly pursued a spot that moved vertically across

the stationary background, median saccadic error was 1.1 deg horizontally and 1.2 deg

vertically, thus being of similar accuracy to when targets were flashed during fixation. In

addition, the vertical component of the memory-guided saccade was much more closely

correlated with the ''spatial error'' than with the ''retinal error''; this indicated that, when

programming the saccade, the brain had taken into account eye movements that occurred

during the memory period.4. When saccades were made to targets flashed during attempted

fixation of a stationary spot on a horizontally moving background, a condition that produces a

weak Duncker-type illusion of horizontal movement of the primary target, median saccadic

error increased horizontally to 3.2 deg but was 1.1 deg vertically.5. When targets were flashed

as subjects smoothly pursued a spot that moved vertically on the horizontally moving

background, a condition that induces a strong illusion of diagonal target motion, median

saccadic error was 4.0 deg horizontally and 1.5 deg vertically; thus the horizontal error was

greater than under any other experimental condition.6. In most trials, the initial saccade to the

remembered target was followed by additional saccades while the subject was still in

darkness. These secondary saccades, which were executed in the absence of visual feedback,

brought the eye closer to the target location. During paradigms involving horizontal

background movement, these corrections were more prominent horizontally than vertically.7.

Further measurements were made in two subjects to determine whether inaccuracy of

memory-guided saccades, in the horizontal plane, was due to mislocalization at the time that

the target hashed, misrepresentation of the trajectory of the pursuit eye movement during the

memory period, or bath.8. The magnitude of the saccadic error, both with and without

corrections made in darkness, was mislocalized by similar to 30% of the displacement of the

background at the time that the target flashed. The magnitude of the saccadic error also was

influenced by net movement of the background during the memory period, corresponding to

similar to 25% of net background movement for the initial saccade and similar to 13% for the

final eye position achieved in darkness.9. We formulated simple linear models to test specific

hypotheses about which combinations of signals best describe the observed saccadic

amplitudes. We tested the possibilities that the brain made an accurate memory of target

location and a reliable representation of the eye movement during the memory period, or that

one or both of these was corrupted by the illusory visual stimulus. Our data were best

accounted for by a model in which both the working memory of target location and the

internal representation of the horizontal eye movements were corrupted by the illusory visual

stimulus. We conclude that extraretinal signals played only a minor role, in comparison with

visual estimates of the direction of gaze, in planning eye movements to remembered target

locations during our illusory paradigms.



Zivotofsky, A. Z., O. B. White, et al. (1998). “Saccades to remembered targets: The effects of saccades

and illusory stimulus motion.” Vision Research 38(9): 1287-1294.

In 10 human subjects, we measured the accuracy of saccades to remembered locations of

targets that were flashed on a 20 x 30 deg random dot display, while they tracked a spot of

light that stepped between three vertical locations. The background was either stationary or

stepping horizontally in synchrony with vertical motion of the spot of light, a condition that

induced a strong illusion of diagonal target motion. Memory-guided saccades were less

accurate horizontally, but not vertically, when the background moved compared with when it

was stationary. The horizontal component of memory-guided saccades correlated better with

the position of the background when the target was flashed than with the position of the

background at the end of the memory period. We conclude that the visual illusion corrupted

the working memory of target location, but had a lesser effect on the estimate of gaze at the

end of the memory period, which seemed to depend more on extraretinal signals. Published by

Elsevier Science Ltd.



Zohary, E., M. O. Scase, et al. (1995). “Mechanisms of Integration of Directional Signals in Dynamic

Random-Dot Displays.” Investigative Ophthalmology & Visual Science 36(4): S396-S396.



Zohary, E., M. O. Scase, et al. (1996). “Integration across directions in dynamic random dot displays:

Vector summation or winner take all?” Vision Research 36(15): 2321-2331.

Recent studies have clearly demonstrated that the activity of directionally selective neuronal

populations in the middle temporal (MT) and medial superior temporal (MST) cortical areas

plays a direct role in the judgment of the direction of visual motion, However, the way in

which the information is derived from a population of neurons remains unknown. Two

principal models have been suggested in the past: the vector summation model suggests that

the responses of neurons encoding all directions of motion are weighted and pooled to obtain

an accurate estimate of the mean direction of motion; the winner-take-all model is based on a

competition between different direction-specific channels, so that decisions are cast in favor of

the channel generating the strongest directional signal. To discriminate between these two

models we generated random dot stimuli that contained an asymmetric distribution of

directions of motion. Human subjects were asked to adjust the global direction of motion to

the upward vertical direction. When the directional signals were of similar strength, subjects

tended to perceive global motion in the mean direction of motion (corresponding to vector

summation), but as one directional signal became more prominent, most subjects' settings

diverged from the mean towards the modal direction of motion. Some subjects could either

match the mean or the modal direction of motion in the display, depending on the task

instructions. These results suggest that the perceptual judgment of direction of motion is not

based on any rigid algorithm generating a single valued output. Rather, human observers are

able to judge different aspects of the distribution of activity in a cortical area depending on the

task requirements. Copyright (C) 1996 Elsevier Science Ltd.



Zohary, E. and A. C. Sittig (1993). “Mechanisms of Velocity Constancy.” Vision Research 33(17):

2467-2478.

Human observers can compare the physical velocities of objects (cm/sec) moving at different

distances quite well, although the objects' retinal velocities (deg/sec) may vary considerably.

This perceptual ability is called velocity constancy. We conducted a number of experiments to

investigate what mechanisms observers use to attain this constancy and if pure motion signals

can also be matched according to their physical speeds. Subjects were asked to match the

velocities of two moving stimuli presented at different viewing distances. The stimuli

consisted of sparse random-dot kinematograms or drifting Julesz patterns. The subjects

matched the true physical velocities of the stimuli provided that the two visual scenes

contained identical size references. Knowledge of the actual viewing distances proved to be

irrelevant for evaluating the physical velocities of the stimuli. We conclude that velocity

constancy is based upon a relative scaling algorithm.



Zucker, S. W., D. G. Jones, et al. (1993). “Random Dot Moire Stereograms Indicate a Distributed Code

for Orientation and Disparity.” Investigative Ophthalmology & Visual Science 34(4): 1439-

1439.



Zucker, S. W., K. A. Stevens, et al. (1983). “The relation between proximity and brightness similarity

in dot patterns.” Perception and Psychophysics 34(6): 513-522.

Eight Ss with normal or corrected vision (2 of whom were aware of the goals of the

experiment) were presented with 3 types of dot patterns as stimuli and asked to identify their

linear orientation: (1) those with a horizontal or vertical orientation, (2) those organized in

either a horizontal/vertical direction or a diagonal direction, and (3) rotated random-dot moire

patterns. Each type of pattern consisted of 2 overlapping populations of dots; one was fixed in

intensity, and the other varied across trials. Two apparent organizations were possible for each

presentation, depending on whether the 2 dot intensities, 1 for each population, were seen as

similar or dissimilar. Results show that dots were virtually never grouped across the

background but were readily grouped when they differed from it, suggesting a purely local

relationship between proximity and brightness similarity in perceptual grouping. It is

suggested that findings reflect early information processing more than mere cognitive

judgments. (22 ref) (PsycINFO Database Record (c) 2002 APA, all rights reserved) Record

709 of 887 in PsycINFO 1978-1984