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HUL 211 Methods of studying objects - Behavioural measures

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					Methods of studying objects

   Behavioural measures




        Snehlata Jaswal


        HUL 211 OBJECT PERCEPTION AND MEMORY
         Behavioural measures
Dependent variables can be:

• Accuracy of response
• Response time (also includes reaction time)




                HUL 211 OBJECT PERCEPTION AND MEMORY
                        Illusions
Misperceptions
– Not perceiving the correct size, shape, colour, etc.
– Subjective contours - perceiving something which
     is not there

Find yourself: Lilac chaser




                  HUL 211 OBJECT PERCEPTION AND MEMORY
Illusions – Vertical Horizontal




        HUL 211 OBJECT PERCEPTION AND MEMORY
Illusions – Muller Lyer




    HUL 211 OBJECT PERCEPTION AND MEMORY
Illusions – Ebbinghaus illusion




         HUL 211 OBJECT PERCEPTION AND MEMORY
Illusions – Chubb ilusion




      HUL 211 OBJECT PERCEPTION AND MEMORY
Illusions – Scintillating grid




        HUL 211 OBJECT PERCEPTION AND MEMORY
Illusions – Hering illusion




      HUL 211 OBJECT PERCEPTION AND MEMORY
Café-wall illusion: the horizontal lines seem irregular but they are in fact parallel




                             Illusions – Café Wall illusion




                                                                    HUL 211 OBJECT PERCEPTION AND MEMORY
Illusions – Ehrenstein illusion




        HUL 211 OBJECT PERCEPTION AND MEMORY
Illusions – Blivet or Devil’s fork




          HUL 211 OBJECT PERCEPTION AND MEMORY
Illusions – Kanisza triangle




       HUL 211 OBJECT PERCEPTION AND MEMORY
Illusions – Necker cube
Studying real objects which are illusory


            Ames room illusion




              HUL 211 OBJECT PERCEPTION AND MEMORY
Studying real objects




    HUL 211 OBJECT PERCEPTION AND MEMORY
HUL 211 OBJECT PERCEPTION AND MEMORY
  Studying real objects which are
rendered unreal with the computer




           HUL 211 OBJECT PERCEPTION AND MEMORY
Studying real objects as they are
  (feature or scene perception)




          HUL 211 OBJECT PERCEPTION AND MEMORY
Studying real objects




     HUL 211 OBJECT PERCEPTION AND MEMORY
Studying real objects




     HUL 211 OBJECT PERCEPTION AND MEMORY
Studying real objects




     HUL 211 OBJECT PERCEPTION AND MEMORY
Studying real objects




     HUL 211 OBJECT PERCEPTION AND MEMORY
Flankers task




HUL 211 OBJECT PERCEPTION AND MEMORY
Flankers task




HUL 211 OBJECT PERCEPTION AND MEMORY
Flankers task




HUL 211 OBJECT PERCEPTION AND MEMORY
Preview search task




   HUL 211 OBJECT PERCEPTION AND MEMORY
Multiple object tracking




     HUL 211 OBJECT PERCEPTION AND MEMORY
Rapid Serial Visual Presentation



  AT%YTHWF%RHK…




         HUL 211 OBJECT PERCEPTION AND MEMORY
                   Simon effect
Simon effect refers to the finding that reaction times are
usually faster and more accurate when
the stimulus occurs in the same relative location as
the response, even if the stimulus location is irrelevant to
the task.

It is named after J. R. Simon who first published the
effect in the late 1960s. Simon's original explanation for
the effect was that there is an innate tendency to
respond toward the source of stimulation.



                   HUL 211 OBJECT PERCEPTION AND MEMORY
             Change detection
Two displays shown either simultaneously or one
after the other

The participant has to detect the change




                HUL 211 OBJECT PERCEPTION AND MEMORY
  Why is change detection so hard?
Limited capacity of the visual system
• We cannot take in all information at once
• We need to attend to sub parts of each image
• We need to actually fixate at each sub part

Limits to memory
• Limited number
• Decay
Change detection using simple objects

Can be used to assess features or bindings

Dependent variable can be:
- Response time
- Accuracy of response




                 HUL 211 OBJECT PERCEPTION AND MEMORY
The stimuli
      Change in features
Any one stimulus changes in
- colour
- shape
- size etc.




          HUL 211 OBJECT PERCEPTION AND MEMORY
               Mask
Breitmeyer and Ogmen (2006, p.2)
 “Visual masking refers to the
 reduction of the visibility of one
 stimulus, called the target, by a
 spatiotemporally overlapping or
 contiguous second stimulus,
 called the mask.”
The stimuli
  Change in feature binding
Feature binding is the process whereby
different features such as shape,
colour, size, orientation, location, etc.
are linked together to form a coherent
representation of the object.

Assessed by a swap detection task
The binding task: Swap detection
                         TEST

 STUDY


                         Same




                        Different
                                          Locations irrelevant

                                 200 ms


                                             Study – test intervals
                                             0 ms        500 ms
                                             1000 ms   1500 ms
                                             2000 ms   2500 ms

                  Randomized                 Unchanged
                    Locations                Locations




    Same           Different                     Same
Note: Stimuli are not drawn to scale                              Different
Changing locations – Initial Display
Changing locations – Test Display
                        Experiment
• Remember shape and colour together, ignore location

• 2×6 factorial experiment (repeated measures)
   – Randomized Locations vs. unchanged locations
   – Study-Test Intervals: 0, 500, 1000, 1500, 2000, 2500 ms


• N=12, 6 males, 6 females, Age 18-25 years
             Apparatus and Stimuli
• In any one display, participants were presented six stimuli
  defined by random combinations of six shapes, six colours,
  and twelve locations.
• Each stimulus subtended 1.6º×1.7º of visual angle. In each
  display they were presented randomly in any six locations
  within an invisible 3×4 grid subtending a 6.1º × 7.8º
  rectangle at a viewing distance of 99 cms.
• All stimuli displayed on a grey background on a 17” (16
  inch/41 cm viewable) computer screen in a room lit by
  overhead lighting.
• Participants could move their eyes freely during the task.
• Responses were collected from a keyboard.
           Precautions and controls
• Articulatory suppression

• Short display time

• Practice: 6 trials of each block type, 12 trials with
  randomized study test intervals

• Counterbalancing of unchanged and randomized conditions


• Randomly selected stimuli for the initial display in each trial
                                          Locations irrelevant

                                 200 ms


                                             Study – test intervals
                                             0 ms        500 ms
                                             1000 ms   1500 ms
                                             2000 ms   2500 ms

                  Randomized                 Unchanged
                    Locations                Locations




    Same           Different                     Same
Note: Stimuli are not drawn to scale                              Different
The stimuli
                               Exp 2: Immediate mask
                               200 ms


                                        100 ms

                                                     Study – test intervals
                                                     100 ms   500 ms
                                                     1000 ms 1500 ms
                                                     2000 ms 2500 ms

                  Randomized                     Unchanged
                    Locations                    Locations




    Same           Different                        Same
Note: Stimuli are not drawn to scale                               Different
                                    Exp 3: Delayed mask
                          200 ms


                                     300 ms


                                              100 ms
Note: Stimuli are not
drawn to scale                                          Study – test
                                                        intervals
                                                        400 ms    500 ms
                                                        1000 ms 1500 ms
                                                        2000 ms 2500 ms
                        Unchanged
                        Locations
                                                   Randomized Locations




            Different      Same                  Same         Different
                               Shapes irrelevant
                                 200 ms

                                          Study – test intervals
                                          0 ms        500 ms
                                          1000 ms 1500 ms
                                          2000 ms 2500 ms
                  Randomized              Unchanged
                      Shapes              Shapes




    Same           Different                  Same
Note: Stimuli are not drawn to scale                          Different
                                       Colours irrelevant

                                 200 ms

                                           Study – test intervals
                                           0 ms        500 ms
                                           1000 ms 1500 ms
                                           2000 ms 2500 ms
                  Randomized               Unchanged
                      Colours              colours




    Same           Different                   Same
Note: Stimuli are not drawn to scale                           Different
          Sequential presentation
To build up the Study-display




One at a time sequential presentation of stimuli drawn to scale
                               Note: Stimuli are not




                                Note: Stimuli are not drawn to scale
         Thank you




HUL 211 OBJECT PERCEPTION AND MEMORY

				
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Description: Object Perception and Memory Lecture Series