Perception
1
Inattentional Blindness
Challenge:
Count the number of passes the white shirts pass!
Video (2mins)
Type of selective attention
Failing to see visible objects when your attention is
directed elsewhere
2
Change Blindness
• You fail to notice a difference in a stimulus (ex. the
person) from just a moment ago
• Focusing on the task (relevant), not the person
(irrelevant)!
• British video (4 mins)
• Daniel Simons (4 mins)
© 1998 Psychonomic Society Inc. Image provided courtesy of Daniel J. Simmons.
Do you see what I see?
Gestalt: German
meaning “whole”
or “form”
When given a
cluster of
sensations,
we tend to
organize them
using gestalt
Constantly
filtering info in
ways that make
sense to us
Figure-ground
relationship:
Define the figure
(focused object) from
the ground (its
surroundings)
Relationship is
continuously reversible
The same stimulus can
trigger more than one
perception
Does this most closely resemble
6 lines or 3 groups of 2?
Proximity: We group nearby figures together
Do you see vertical or horizontal lines?
Similarity: group similar objects together
http://deadspin.com/stupid-nike-uniforms-wreaking-havoc-on-colorblind-nfl-f1742272136
How do you draw an X?
Continuity: perceive smooth, continuous
patterns rather than discontinuous
How many?
Connectedness: if uniformed and linked, we
perceive each set of two dots and lines as a
single unit
This is a _______??
Closure: we fill
in gaps to create
a complete
whole object
We assume the
circles are
complete and just
blocked by a
triangle
Binocular Cues
cues that depend on using BOTH eyes
Retinal disparity
You see two angles of every object
Convergence
When objects get closer to your
face, you cross your eyes to
continue using your fovea
Monocular Cues
Relative size
Interposition
Relative motion
Texture gradient
Relative height
Linear perspective
Shadowing
Depth cues that DO NOT
require both eyes
Monocular Cues
Which pencil is closer?
Relative Size: if we assume two objects are the same size,
we perceive the smaller retinal image as farther away
Which letter is the closest?
Interposition: objects that block the view of
other objects must be the closest
Relative Motion:
distant objects seems to move
with you while nearby objects
go by rapidly
Smaller objects appear to go
faster than larger objects
moving at the same speed
Monocular Cues
Texture Gradient
Surface quality of an
object; we see less
texture on something
that is farther away.
Relative Height
Distant objects
appear relatively
higher in your field of
vision than close
objects.
Monocular Cues
Linear Perspective
Distance cue; parallel
lines converge, as they
move away from us
Shadowing
Given two identical objects,
the dimmer one will seem
farther away
Gives clues about depth
Gives clues about movement
(1:01-2:50)
Motion Perception
Stroboscopic effect (flip book effect)
Film is not motion! At 24 slides per second we perceive as motion
When the information is limited, the brain often makes assumptions
based on what it knows. In the case of spinning rims, the relative
position of the individual spokes and the light source which makes
them visible can combine to create an optical illusion of backwards
motion.
forza motorsport 5 (2:15)
16
Perceptual
Illusions
Julian Beever
(3:00)
Motion Perception
Phi Phenomenon: blinking lights make it look like
light is jumping from one point to another creating
the illusion of motion.
Perceptual Interpretation
Which is a
darker shade
of gray?
A or B?
Perceived color depends on the amount of light
an object reflects relative to its surroundings.
Lightness Constancy
Perceptual Interpretation
When we are unfamiliar with the size of an object,
monocular cues (linear perspective) tricks us in
perceiving the false size of the object.
The monster farther away is larger, right?
Perceptual Interpretation
The moon looks huge when it’s near the horizon,
but it’s actually always the same size!
We have no perspective of how far away the
moon is in high sky since we don’t have a horizon
to compare it to.
Moon Illusion
Perception Highlights
Start at 8:00-15:00
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