Perception
How we organize and interpret
sensory information
Selective Attention Video
Card trick
Basketball game
Selective attention - we can only focus
awareness on a limited part of what we are
sensing.
Cocktail party effect –
type of selective
attention in which you
can attend to only one
voice at a time
Cell phones and driving?
Listening to music and
studying?
Visual Capture
The tendency for vision
to dominate your
senses.
At an IMAX movie, it
feels like you are
moving because it looks
like you are moving.
Your vision dominates
over your vestibular
system.
Parallel processing –
processing many things at once
Man who mistook his
wife for a hat – could
see form but not the big
picture
Colorblindness with
functional cones
Motion blindness
Blindsight
Perceiving Images
The first step in perceiving
an image is determining
the figure and ground.
Do you see the arrow?
Gestalt and the Urge to Organize
Other gestalt principles
Simplicity
Gestalt Principles: Closure
Gestalt Principles: Continuity
Gestalt Principles: Proximity
Gestalt Principles: Similarity
Gestalt and the Lion King
http://www.youtube.com/watch?v=skD2gyP1cCs
http://www.youtube.com/watch?v=zdtMTixlBFI
Motion Perception
How does the brain recognize an object is moving?
How does it interpret the direction of movement?
Brain interprets shrinking
objects as receding
and enlarging objects
as approaching
Stroboscopic Effect
the perception of motion produced by a
rapid succession of slightly varying
images (animation, movies)
Stroboscopic effect
Phi phenomenon
an illusion created when two or more
adjacent lights blink on and off in
succession, creating the perception of
movement (lighted signs, illusions)
Perceptual Constancy
the ability to perceive an object is the same even as the illumination and
retinal image changes.
Shape Constancy- perception that shape of an object
doesn’t change just because image on the retina
does.
How many right angles do you see?
Perceptual Constancy
Size constancy (King Koch or the incredibly
shrinking teacher) – perception that an
object’s size remain the same even as the
retinal image changes.
Perceptual Constancy
Color Constancy – the perception that familiar
objects have a consistent color, even if
changing illuminations alter the wavelength
reflected.
Perceptual Constancy
Lightness constancy – the perception that
familiar objects have a constant lightness,
even while illumination varies.
Visual Cliff – used to check for depth
perception.
Pre-Renaissance Art
Jesus on Way to Calvary
Simone Martini The Holy Innocents by Giotto di Bondone.
Renaissance Art
Leonardo Da Vinci, The Last Supper
Masaccio, Trinity (ca. 1425).
Depth Perception
Monocular Depth Cues
Linear perspective
(parallel lines appears to
converge on a vanishing
point)
Relative height (more
distant objects are
higher)
Relative size (more
distant objects are
smaller)
Depth Perception
Monocular Depth Cues
Relative clarity (objects in
the distance appear hazy)
Overlap/interposition
(continuous outlines
appear closer)
Depth Perception
Monocular Depth Cues
Texture gradient (texture
details, like roughness,
diminish with distance)
Depth Perception
Monocular Depth Cues
Light and shadow
How many can you identify here?
Depth Perception
Monocular Depth Cue
Motion parallax (or relative motion) – Distant
objects will appear slow in comparison with close
objects even when the two are moving at the same
speed
Think of an airplane traveling overhead.
http://www.youtube.com/watch?v=-
OmK3rGk__I&NR=1
Depth Perception
Binocular depth cues – require two eyes
Retinal disparity – the greater the difference
between the images on your two retina, the closer
the object (“camera 1, camera 2”, “finger sausage”,
hole in the hand)
Convergence – the greater your eye muscles must
strain (or converge) to focus on an object, the closer
the object (notice how hard your eyes strain when
you focus on the tip of your nose).
Size-distance relationship
When other monocular cues tell us an
image is further away, it actually
appears larger.
Horizon Moon
High moon on a
clear night.
Horizon moon
Which object would you need to hold at arms
length to just cover the moon?
•BB •Baseball
•Pea •Softball
•Dime •Small salad plate
•Penny •Large dinner plate
•Nickel •Frisbee
•Quarter •Basketball
•Golf ball •Beach Ball
High moon on a clear night.
Which object would you need to hold at arms
length to just cover the moon?
•BB •Baseball
•Pea •Softball
•Dime •Small salad plate
•Penny •Large dinner plate
•Nickel •Frisbee
•Quarter •Basketball
•Golf ball •Beach Ball
Muller-Lyon Illusion
Which is longer?
Muller-Lyon Illusion
Perceptual Adaptation
Perceptual Set
Perceptual Set
Perceptual Set
TIME FLIES I CANT THEYRE TOO FAST
FOLK CROAK SOAK
MacDonald MacHenry MacDuff
Machinery
Context Effects
I/O Psychology – Human Factors
I/O Psychology – Industrial/Organizational psychology
Human factors – a branch of psychology that explores how
people and machines interact to create machines that are
more efficient and safer.
http://www.baddesigns.com/mopsnk.html
http://www.baddesigns.com/shower1.html
http://www.baddesigns.com/autoicons.html
http://www.baddesigns.com/elevator.html
http://www.baddesigns.com/remote.html
http://www.baddesigns.com/carseat.html
http://www.baddesigns.com/ranges.html
Extrasensory Perception
Telepathy – mind reading
Clairvoyance – perceiving remote events
Precognition – Knowing things before they
happen
Telekinesis (psychokinesis) – moving
objects with one’s mind (not technically
ESP)