Perception
Know the slides with the owl icon for the quiz
The process of organizing and interpreting
information, enabling us to recognize
meaningful objects and events.
Sensation
• Process of
detecting &
transmitting
energy from the
environment to
our brain.
• Mechanical
(physical)
• Helps us obtain
needed info
Perception
• Process by which
we select,
organize, &
interpret our
sensations
• Active &
subjective
(cognitive)
• Depends on many
factors
Group A
• You are going to look briefly at a picture
and then answer some questions about
it. The picture is a rough sketch of a
poster for a costume ball. Do not dwell
on the picture. Look at it only long
enough to “take it all in” once. After this,
you will answer YES or NO to a series of
questions.
Conclusion
• Top Down processing – you go beyond
the sensory information to try to make
meaning out of ambiguity in your world
• What you expect (your experiences and
your perceptual set) drives this process
• Today we will see what expectations we
all have in common.
Without ATTENTION, there is no
PERCEPTION
• We don’t perceive what we don’t
attend to!
• Attention is selective
• Selective Attention: focused
awareness on only a limited amt. of
a stimulus at any given moment.
• The “Cocktail Party Effect”
Perceiving the world
1st perceptual task:
• We distinguish an object (the
figure) from its surroundings
(the ground)
• Example:
» Words (figure)
» Page (ground)
Reversible Figure-Ground
Relationships
• Ambiguous, unstable
perceptions
• Our attention goes back & forth
(Selective Attention)
• Examples: The Necker Cube
and The Rubin Vase
The Necker Cube
The Rubin Vase
Perceiving the world:
2nd perceptual task:
• We organize perceptual
elements into meaningful
patterns.
Bottom-up Processing
Analysis of the stimulus begins with
the sense receptors and works up to
the level of the brain and mind.
Letter “A” is really a black blotch broken
down into features by the brain that we
perceive as an “A.”
Bottom-up Processing
• Perceiving something by focusing
on its detailed aspects
• Building a complete perception
piece by piece (from the bottom
up)
• “Data-driven processing”
Example of Top-Down
Processing
• Aoccdrnig to rscheearch at Cmabrigde
Uinervtisy, it deosn't mttaer in waht oredr the
ltteers in a wrod are, the olny iprmoetnt tihng
is taht the frist and lsat ltteer be at the rghit
pclae. The rset can be a total mses and you can
sitll raed it wouthit a porbelm. Tihs is bcuseae
the huamn mnid deos not raed ervey lteter by
istlef, but the wrod as a wlohe.
Top-down Processing
• Perceiving something by focusing
on its broad pattern (not its
specific features)
• Using contextual info or our prior
knowledge to organize pattern into
a meaningful whole
• “Conceptual-driven processing”
Gestalt Principles of Perceptual
Organization
Gestalt = an organized whole
• Gestalt psychologists study
our tendency to integrate
pieces of info into
meaningful wholes.
4 Gestalt Principles of Perceptual
Organization
1. continuity
2. Closure
3. proximity
4. similarity
1. Continuity
• The tendency
to perceive a
series of
points or lines
as having
unity
2. Closure
• The tendency
to perceive a
broken figure
as being
complete or
whole
3. Proximity
• The tendency to
group objects
together that are
near one another
• “Everyone from
______ is
_______.”
• The tendency to
group objects
together that are
similar in
appearance
• Another major
explanation for
our tendency to
stereotype
various groups of
people
4. Similarity
FACTORS THAT INFLUENCE PERCEPTION
1. Motivation
2. Expectation
3. Context
4. Emotion
5. Culture
Perceptual Set
• “A perceptual bias (predisposition or
readiness) to perceive particular features
of a stimulus (Allport, 1955).
• A mental predisposition to perceive one
thing and not another.
• Can be caused by our experiences,
assumptions, and expectations
• Can impact visual and auditory perception
Perceptual Set
A mental predisposition to perceive one thing
and not another. What you see in the center
picture is influenced by flanking pictures.
From Sheard, 1990.
The Influence of Motivation
1. Rich & poor children estimate the
size of coins
–Poor kids over-estimated size of
every coin
2. 4-8 yr. olds draw Santa before &
after Xmas
–Larger before & smaller after
The Influence of Expectations
• Often, what we perceive is
influenced by what we expect to
perceive.
• Can you think of other real life
examples?
Perceptual Set
Other examples of perceptual set.
Dick Ruhl
Frank Searle, photo Adams/ Corbis-Sygma
(a) Loch ness monster or a tree trunk;
(b) Flying saucers or clouds?
The Influence of Context
• A given stimulus may trigger
radically different perceptions
depending on the immediate
context.
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3/22/2016
The Influence of Emotion
• Our emotional state will affect the
way we perceive something
• Good mood vs. Bad mood
•
• State dependent memory
• Perceptual Constancy
–Our tendency to perceive objects as
stable and unchanging despite
changing sensory information
1. Size constancy
2. Shape constancy
3. Color/Brightness constancy
Size Constancy
Shape Constancy
Color/Brightness Constancy
How Do We Perceive Depth?
1. Monocular Cues
2. Binocular Cues
Mono cular Cues
• Stimuli
suggestive of
depth that c
only one eyean
be perceived
with.
1.
2.
3.
4.
5.
Linear Perspective
Relative Size
Texture Gradient
Interposition
Light and
shadowing
6. Motion Parallax
Linear Perspective
Perceiving parallel lines as coming closer together, or
converging, as they recede from us. The more the
lines converge, the greater their perceived distance.
Relative Size
Perceiving larger objects as being closer to us.
Texture Gradient
Perceiving objects with rougher textures as being closer
Interposition
Objects that
block other
objects tend to
be perceived as
closer.
Light and Shadowing
Perceiving shadows and highlights as giving
depth to two-dimensional objects.
Motion Parallax
• Perceiving that NEARBy objects
appear to move more rapidly in
relation to our own motion.
Bi nocular Cues
• Stimuli suggestive of depth that
involve simultaneous
• perception by BOTH eyes
1. Retinal Disparity
2. Convergence
Binocular Cues
Retinal disparity (or binocular disparity): Images from the
two eyes differ. Try looking at your two index fingers when
pointing them towards each other half an inch apart and
about 5 inches directly in front of your eyes. You will see a
“finger sausage” as shown in the inset.