The Role of Experience
1. Perceptual Development
2. Effects of Learning and Cognition
3. Development Vs Hardwiring
Anthony J Greene
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Perceptual Development
The Measurement of Infant
Perception
• A reliable tendency to stare at new stimuli
• Comfort responses and preferences for
familiar stimuli
• Reliable surprise reactions when
configurations are altered
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The Development of Visual Acuity
• Vary spatial frequency and
contrast compared to a gray
swatch
• The highest frequency and
smallest contrast that
produce a response
determine the acuity of
infant perception
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The Development of Visual Acuity
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The
Development
of Visual
Acuity
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Stereopsis: Use it or lose it
• At Birth, the nerve fibers at the edge of column
boundaries are poised to cross over and make
connections with columns from the opposite eye
that have similar receptive fields
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Stereopsis: Use it or lose it
• With normal development, corresponding inputs
from different eyes cause nerves to overlap
• As with phase detectors, different eccentricities
are detected in slightly different regions of cortex.
Such regions then discern different disparities.
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Stereopsis: Use it or lose it
• If the inputs do not correspond (e.g. child may be
cross-eyed or have a wandering eye), the inputs do
not overlap and stereopsis does not develop.
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Object Constancy
• By 2 months of age, most
children can detect that
an object is missing
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Newborn
The Time
Course of
2 Months
Perceptual 3 Months
Development
2 Weeks
1 Month
4 Months
5 Months
6 Months
1. Recognize mothers face
2. Discriminate mothers voice
3. Intermodal matching
1. Moving stimuli
1. 20/600 Vision
2. Can discern speech from other
voice noises
1. Some color vision
2. Object constancy
1. Perception of Facial Expressions
2. Good color vision
3. Binocular fixation
4. Smooth eye movements
1. Object Categories
2. Biological Movement
3. Binocular Disparity
1. Pictorial Depth Cues
1. High Visual Acuity
2. Hearing threshold close to adult
3. Speech Classification
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The Development of Myopia
(childhood into adulthood)
• With excessive up-close viewing, the strain on the
lens and cilia eventually cause the eyeball to
shorten to accmodate more easilly
– The Air Force Academy
– Eskimos
– Chicks
• This process can be prevented and reversed by
using reading glasses and engaging in distance
viewing (e.g., lots of outdoor activity)
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COGNITIVE ASPECTS OF
PERCEPTION
Top-Down Aspects
1 Categorization
2 Attention
Perception
3 Identification &
Recognition
4 Competition Between
Top-Down & Bottom-Up
Information
5 Resolving Ambiguity
6 Context
7 Imagery
8 Perception & Action
9 Perception is Malleable
10 Is Perception Modal?
11 Concepts
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1 Categorization
Memory
Grouping like objects - category exemplars
Generalization
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2 Attention
Behavioral and Physiological phenomenon
Acquisition of Sense Data : Cognitive gating
of sensory/perceptual input -- Guides
Acquisition of Sense Data
Competition between Top-Down
& Bottom-Up information
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Cognitive Gating
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Cognitive Gating
There are
benefits to
keeping
your mind
on what
you’re
doing
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The Physiology of Attention
• Amplification
(the Pulvinar of the Thalamus)
• De-amplification
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3 Identification & Recognition
• Perceptual systems
learn to recognize
• Identification for
previously seen
items is faster and
more reliable,
regardless of
whether or not you
consciously
remember
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Disorders of Identification or
Recognition
• V3: Visual agnosia
• IT: Associative agnosia
• Fusiform gyrus of IT: Prosopagnosia
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4 Process Competition
Irrelevant
Information
Facilitation and
Interference
Stroop
Interference
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Stroop Interference
TRUCK
PLATE
BLUE
TREE
RED
PURPLE
YELLOW RED
DESK
BUCK
STRAW
GREEN
GRAY
BLUE
PURPLE
GREEN
GRAY
YELLOW
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5 Resolving Ambiguity
Purpose of perception is unambiguous
information
Gibson- perception is a behavior which
actively resolves ambiguity
Perception can be viewed as a probability
funnel
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6 Context and Perception
Context can serve to constrain or resolve
ambiguity - source of additional information
(associative) and clues.
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7 Imagery
•
•
What color is your neighbors house?
Perception in the absence of the stimuli an aspect of memory
I Mental Rotations
II Activation of Perceptual Areas
III Damage to Perceptual Areas Disrupts
Imagery and Memory
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Mental Rotation
Reaction Time (RT) Study
1 Shepard Mental Rotation - Internalized Perception
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Mental Rotation (cont.)
3.5
•Straight slope line
indicates mental
rotations of 600/sec
3.0
2.5
2.0
•If it weren’t a
rotation, the slope
would be either flat
or irregular
1.5
1.0
0.5
0.0
15
30
45
60
75
90 105 120 135 150 165 180
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Mental Rotation (cont.)
• The fact that the result is a straight line indicates
that the subjects must be rotating through the
intermediate positions.
• Analog Process - Analogous to Physical Rotations;
mental rotation is constrained in the same way that
our physical interaction with the environment in
constrained
• The further apart the objects are, the longer it
takes to mentally rotate them.
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Mental Rotation (cont.)
Can blind people do mental rotation? (i.e. Is vision
necessary for mental rotation?)
2 Marmor & Zaback - 2-D mental rotation in the Picture
Plane
• Subjects:
– Sighted Blindfolded
– Congenitally Blind
– Blind (Late Blindness; have a visual frame of reference)
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Mental Rotation (cont.)
• Stimulus:
– The figures used here are simpler than those used by
Shepard.
– Wooden objects fastened to a larger, flat piece of wood.
– Present one object to the Left Hand.
– Present another (possibly different) object in a different
orientation to the Right Hand.
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Mental Rotation (cont.)
3.5
3.0
2.5
2330/sec 1140/sec 590/sec
2.0
1.5
1.0
0.5
0.0
15 30 45 60 75 90 105 120 135 150 165 180
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Mental Rotations (cont.)
• Because all of the lines are straight subjects are
constrained to the physical/mental rotation
through intermediate positions.
• Vision is NOT necessary to do rotation; vision just
makes for faster mental rotations.
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8 Perception & Action
• Recall Gibson’s theory that perception is a
behavior
• As such, part of action must be to help
constrain perception (e.g., exploration) or
inform (foraging)
• Similarly, action is directed and updated by
perception
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9 Perception is Malleable
• Prism Effects on reaching
• Facilitation
• Perception is influenced by expectation
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10 Is Perception Modal?
Do the senses influence one another?
1. Synesthesia
2. Barn Owl: Optic Tectum (Colliculus)
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11 Concepts
• Pigeons can learn complicated concepts
• From some points of view, concepts are no
more than configurations of perceptual
information
• Or, at least, conceptual processes evolved
for the purpose of making the best use of
perceptual information
• What you perceive depends upon what you
know
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Do Concepts Help Us Figure
Out What We’re Looking At?
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Innate Vs. Developed
Nature Vs. Nurture
Two Species on Their Day of Birth
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Is
Perception
Innate?
Nature vs.
Nurture
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Turn That
Frown
UpsideDown
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Facets of Perception
That Are Hardwired
1. Bottom-Up Processes
2. Neural Organization
3. Reflex Mechanisms
1. The Reflex Arc
2. Visual and Auditory Orientation Reflex
4. Range of Perception
5. Capacities of Perception
1. Attention?
2. The Ability to Learn Perceptually and Conceptually
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Facets of Perception
That Are Hardwired
1. Bottom-Up Processes?
2. Neural Organization?
3. Reflex Mechanisms
1. The Reflex Arc
2. Visual and Auditory Orientation Reflex
4. Range of Perception
5. Capacities of Perception ?
1. Attention?
2. The Ability to Learn Perceptually and Conceptually?
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Facets of Perception
That Require Development
1. Top-Down Processes
1. Attention
2. Learning
2. Fine-Tuned Functioning
1.
2.
3.
4.
Acuity
Stereopsis
Perceptual Facilitation (Priming)
Generalization vs. Discrimination
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Conclusion
•Evolution favors what?
•Speed versus flexibility trade-off
It favors both, but under different circumstances. In
rapidly changing environments, or in species that
occupy varied habitats (like humans: everything
from the equator to near the poles, including jungle,
desert, plains, citys, farm, etc.) then flexibility is
favored. In species where the lifespan is short and/or
mortality rate is high, speed is favored.
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