Unit 4: Sensation &
Perception
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Definitions
Sensory Systems
Vision
Hearing
The Other Senses
Perception
STIMULUS
A form of energy in the
environment which can elicit a
response.
SENSE
A particular physiological
pathway for responding to a
specific kind of stimulus energy.
SENSATION
The process by which stimulus
energies are detected and
encoded.
TRANSDUCTION
The breaking down of stimulus
energies into neural impulses.
What's out there (stimuli) is
far removed from what we
sense and perceive!
The Senses
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Vision
Audition
Gustation
Olfaction
Touch
Some other senses:
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Equilibrium-balance
Kinesthesis-limb position & movement
“Internal” Sense
Vision
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Physiology of the Eye
How We See Color
Vision- Receptors
Receptors in the Human Eye
Cones
Rods
Number
6 million
120 million
Location in
retina
Center
Periphery
Sensitivity in
dim light
Low
High
Color sensitive?
Yes
No
How we see color
 Trichromatic
(three color)
Theory
– Young and
Helmholtz
– three different
retinal color
receptors
red
 green
 blue
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How we see color
Opponent-Process Theory- opposing retinal
processes enable color vision
“ON”
“OFF”
red
green
green
red
blue
yellow
yellow
blue
black
white
white
black
Color-Deficient Vision
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People who suffer
red-green blindness
have trouble
perceiving the
number within the
design
Audition
Physiology of the Ear
The Other Senses
Gustation
Four basic taste sensations:
SWEET, SOUR, SALTY, BITTER
The Other Senses
Olfaction
Physiology
Smell
Seven Basic Smells?
 Floral
 Minty
 Musky
 Pungent
 Putrid
 Ethereal
 Camphoraceous
The Other Senses
Touch
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Four basic touch
sensations:
PAIN, PRESSURE,
WARM, COLD
Pressure sensitivity
and the two-point
discrimination
PERCEPTION
The mental process by which
sensations are organized and
interpreted.
Nature Theories
The Gestalt Psychologists
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Our perceptual abilities are inborn!
Gestalt means-the whole is greater
(different) than the sum of its parts.
Gestalt principles of perceptual
organization
Proximity
A perceptual tendency to group
together visual & auditory
events that are near each other.
Similarity
A perceptual tendency to group
together similar elements.
Continuity
A perceptual tendency to group
stimuli into smooth, continuous
patterns.
Closure
A perceptual tendency to fill in
gaps thus enabling one to
perceive disconnected parts as a
whole object.
Figure-Ground
The organization of the visual
field into objects that stand out
from their surroundings.
Nature Theories
Depth Perception
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Our ability to see depth or see in
three dimensions.
Eleanor Gibson & the visual cliff
Depth Perception
Binocular & Monocular Cues
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Retinal Disparity
Convergence
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Relative Size
Overlap/Interposition
Texture Gradient
Relative Motion
Linear Perspective
Nurture Theories
Our abilities to perceive
are learned through experience!
Nurture Theories
Perceptual Constancy
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Perception that objects have a
constant size, shape and color
regardless of sensory changes.
Nurture Theories
Perceptual Set
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A mental predisposition that
influences what we perceive.
WHAT INFLUENCES OUR
PERCEPTUAL SET?
Immediate context, culture, etc.