Human Cognitive
Processes: psyc 345
Ch. 3: Perception
Takashi Yamauchi
© Takashi Yamauchi (Dept. of Psychology, Texas A&M University)
Homework & Questions
Q1: How do we perceive?
– If you are going to develop a theoretical model
of perception, how does it look like?
– Describe your processing model of perception.
Q2: How does the brain become tuned to
respond best to things likely to appear in the
environment?
Visual illusion
• Let’s take a look at visual illusions and
check how your model can explain these
illusions.
– Ponzo illusion
– Muller-Lyer illusion
– Ames room
• http://www.youtube.com/watch?v=Ttd0YjXF0no
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Fig. 3-6, p. 50
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The figure represents “some thing.”
The contours belong to the figure rather than to the
ground.
Which one is the figure and which one is the ground?
Symmetric items tend to be seen as a figure.
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(A)
(B)
(A)
(B)
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Is your model consistent with these
visual illusions?
• How does your model explain these
illusions?
• What’s wrong with your models?
• Why do we have these illusions?
• Demonstration
– Ames room
• http://www.youtube.com/watch?v=Ttd0YjXF0no
Some examples
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Tired
Old
Sick
Dark
Slow
Heavy
Hospital
ugly
death
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Beautiful
Young
Fresh
Fast
Energy
Juicy
Clean
cheerful
Vigorous
• Experience influences perception a great
deal.
• We need a top-down process as well as a
bottom-up process.
• Direct perception theories
– Bottom-up processing
– Perception comes from stimuli in the
environment
– Parts are identified and put together, and then
recognition occurs
• Constructive perception theories
– Top-down processing
– People actively construct perceptions using
information based on expectations
Bottom-up
and topdown
processes
Fig. 3-4, p. 59
Perceptual Organization and Gestalt
Psychology
• “Gestalt” means “whole.”
• Organizational principles:
– Similarity
– Proximity
– Continuity
Law of similarity
Similar things are put together
Items with similar
colors are put
together
Law of proximity
• Things that are close to each other are put together.
Law of good continuity
We tend to put things together when they show nice
continuity.
Why do we need top-down
knowledge?
• Because the bottom-up process is inherently
ambiguous.
Why computers have trouble
perceiving objects?
• The bottom-up process is difficult.  solving the
inverse projection problem
• Computers do not have a large amount of
background knowledge as we have.
• Humans have an incredible accumulation of
knowledge.
• Use knowledge to solve perception
problems
Fig. 5-4, p. 96
Neurons and the Environment
[Q2] How does the brain become tuned to respond
best to things likely to appear in the environment?
– Some neurons respond best to things that occur
regularly in the environment
– Neurons become tuned to respond best to what we
commonly experience
– Neurons that respond to similar visual information
(e.g., shape, motion, color, faces, etc) are grouped
together.
Two visual pathways (where &
what systems)
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Two visual pathways (where / how & what
system)
Patient D. F had bilateral damage to
the ventral path.
Carbon monoxide poisoning at
age 35.
• Video clip: NPR
• NPR: Blind man sees with subconscious eye
(12/23/08); Interview and video record
– This can be used as evidence for the “how” pathway.
– http://www.npr.org/templates/story/story.php?storyId=9
8590831
– A blind man who damaged the occipital lobe can still
navigate and walk without bumping into objects.
The monkey had to select the
correct object to get the food
reward
Object
discrimination
task
Landmark
discrimination
task
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The monkey had to select
the food well close to the
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cylinder.
Object
discrimination
task
Can’t do the object
discrimination task
but can do the
landmark
discrimination task
Landmark
discrimination
task
Can’t do the landmark
discrimination task
but can do the object
discrimination task
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Modularity: structures for faces,
places, and bodies
Figure 4.18 (a) Monkey brain showing
location of the inferotemporal cortex (IT)
in the lower part of the temporal lobe. (b)
Human brain showing location of the
fusiform face area (FFA) in the fusiform
gyrus, which is located under the temporal
lobe.
Prosopagnosia
• Episode from
• “The man who mistook his wife for a hat”
• By Oliver Sacks
– Oliver Sacks interview
– http://www.youtube.com/watch?v=zQPI0BIkO
kE
Copies of the black (A)
and
the white (B) vertical
contour.
Copies of the black (A)
and
the white (B) diagonal
contour.
• DVD: the mind eye (Ch.6 – Ch. 8) (10min)
– Agnosia (Ch. 8)
– Propasognosia (Ch. 6 - 7)
Mirror neurons
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Mirror neurons
• Mirror neurons respond to a particular
“kind” of action (e.g., grasping) AND
observing someone doing the action.
The activity of a particular neuron in the
premotor area of a monkey.
The activity of a particular neuron in the premotor area of a
monkey.
(a) This neuron responded when the monkey watched the
experimenter picking up the peanut.
(b) This neuron also responded when the monkey actually
picked up the peanut.
(c) This neuron did not respond when the monkey watched
the experimenter pick up the food with pliers.
Mirror neurons
• Respond not only when you are doing a
particular action.
• But also when you watch someone doing it.
• This neuron gives you a general
characteristic of an action.
What are mirror neurons for?
• Facilitate learning by imitation.
– Language development
– Skill learning
• Social interaction
– Empathy (understanding others or what others
think)
– Connecting with others
• Autism may be caused by the deficiency in
mirror neurons
• Video clip from NOVA (PBS)
– 15 min
– http://www.pbs.org/wgbh/nova/sciencenow/320
4/01.html