Term
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Definition
– Process by which sense organs gather information
about environment
– Indication that something is there
– Something triggers a dendrite of the first neuron |
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Term
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Definition
– Process by which the brain selects, organizes, and
interprets sensations
– What is it that I am hearing, seeing, etc. |
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Term
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Definition
1) No 1-1 correspondence between physical and
psychological reality
– Alternative perceptions of any given sensation
2) Sensation and perception are active processes 2) Sensation and perception are active processes
– We focus on stimuli that are relevant to ourselves
3) Sensation and perception are adaptive
– We adapt to key stimuli our environment |
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Term
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Definition
– Converting a sensation into an internal electrical
signal to convey to the CNS |
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Term
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Definition
– Minimal amount of physical energy needed for
someone to notice a stimulus
– Defined as the level at which individual would
detect stimulus 50% of the time
– Varies from person to person
• May vary with expectations, motivation, stress |
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Term
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Definition
• Just noticeable difference (jnd)
– The lowest level of stimulation required to sense
that a change in stimulation has occurred
• The level of the original signal is key to
detecting just noticeable differences
– A person will notice adding a small candle in a dark
room, but not adding the same candle to bright
sunlight |
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Term
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Definition
• For two stimuli to be perceived as differing in
intensity, the second must differ from the first
by a constant proportion
• Th ti f h i i t it i d t The ratio of change in intensity required to
produce a jnd is the Weber Fraction
• For weight Weber’s fraction is 1/50
– 50 pound bag= Add 1 pound to achieve jnd
– 100 pound bag= Add 2 pounds to achieve jnd |
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Term
| Fechner’s Law(dont need to know) |
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Definition
• Subjective magnitude of a sensation grows as a
proportion of the logarithm of the stimulus
• Suggests that all just noticeable differences are
creatd le equa
– Each additional jnd feels like one incremental unit in
intensity |
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Term
| Steven’s Power Law(dont need to know) |
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Definition
• As the perceived intensity of a stimulus grows
arithmetically, the actual magnitude of the
stimulus grows exponentially
• Key conclusion from Weber, Fechner, Stevens:
– Sensation has direct relationship to physical stimuli.
– However, psychological experience is not exact
copy of external reality |
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Term
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Definition
• The tendency of sensory systems to respond less
to stimuli that continue without change
– Adjust to darkness of a movie theater
– Adapt to a high sound level in a sports stadium
• Prevents sensory overload |
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Term
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Definition
• Light is travels in wavelengths, with higher or
lower frequency
• Receptors in eye detect from 400-700 nm
wavel theng
• Objects that reflect a lot of light appear bright;
objects that absorb a lot of light appear dark |
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Term
| Receptors in eye detect from _______ nm |
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Definition
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Term
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Definition
| detects light: where light is detected |
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Term
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Definition
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Term
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Definition
| opening in iris to control |
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Term
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Definition
pigmented tissue with muscles to constrict or
dilate pupil |
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Term
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Definition
• Rods= black and white
• Cones= color and fine detail
– Photoreceptors stimulate bipolar cells, which excite
ganglion cells
– Axons of ganglion cells join to form Optic Nerve
– Optic Nerve carries information from retina to brain |
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Term
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Definition
center of retina, most sensitive to small
detail |
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Term
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Definition
| spot where optic nerve leaves the eye which has no photoreceptors |
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Term
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Definition
• Impulses from optic nerve go to Optic Chiasm
– Nerve splits, so information from right visual field
goes to left hemisphere, and vice versa
• Information on t o path a s Information on two pathways
– Lateral geniculate nucleus in the thalamus and then
primary visual cortex in occipital lobe
– Superior Colliculus in the midbrain
• Directs further eye movement |
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Term
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Definition
– First stop for interpreting visual information
– Feature detectors
• Only discharge when stimuli matches a given pattern
•
– The “What” pathway determines what an object is
– The “Where” pathway determines where object is,
how it is moving, and how to move toward it
– Only afterwards does a fully integrated
understanding form |
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Term
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Definition
• Color has three psychological dimensions:
– Hue: sensory quality most people consider color
– Saturation: color purity vs mixing with white/black
– Lightness: extent to which color is dark or light |
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Term
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Definition
explains color perception
in the retina
– Three color receptors in eye
• Red, Green, and Blue |
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Term
Opponent-process theory
(opponent of trichromatic theory) |
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Definition
operates at higher
visual centers in brain
– Three antagonistic color systems in visual system
• Blue-yellow
• Red-green
• Black-white |
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Term
| Mixing paint is subtractive: |
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Definition
– Each new paint color blocks out reflected
wavelengths that reach the eye
• Yellow paint reflects only yellow wavelengths
• G i t fl t l th t b b d b bl Green paint reflects wavelengths not absorbed by blue or
yellow paints. |
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Term
| Mixing light is additive: |
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Definition
– Light of different wavelengths reach eye
• Light blends within eye to cause perception of color |
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Term
Frequency
(of sound waves) |
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Definition
– Number of times sound wave cycles per second
– Pitch is psychological property corresponding to
frequency
– Timbre is psychological property corresponding to
complexity of the sound |
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Term
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Definition
– Height and depth of sound waves
– Loudness is psychological property corresponding to
pitch |
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Term
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Definition
| – Sound waves enter ear through auditory canal |
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Term
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Definition
Eardrum is at end of auditory canal
• Set in motion by sound waves
– The eardrum sets ossicles in motion
• Ossicles amplify sound and transfer vibrations to inner ear |
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Term
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Definition
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Term
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Definition
is involved in hearing
– Tube in inner ear in which sound is transduced
– Basilar membrane separates cochlear chambers;
– Hair cells attached to basilar membrane move,
resulting in action potentials in sensory neurons |
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Term
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Definition
– Different areas of basilar membrane respond to
different frequencies
– Best explains transduction at high frequencies |
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Term
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Definition
– Rate of vibration of the basilar membrane
transforms frequency into pitch
– Best explains transduction at at low frequencies |
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Term
| Auditory Pathway in Brain |
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Definition
• Auditory nerve projects to medulla
– Majority of fibers cross to other hemisphere
• Axons then go to midbrain and thalamus, then
to auditory cortex
– Large part of auditory cortex that responds to the
frequencies of human speech |
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Term
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Definition
• Identification of location of a sound in
space
• Binaural Neurons respond to relative
differences in the loudness and timing of
sensory signals transduced by the two ears |
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Term
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Definition
(Smell)
• Enables us to detect danger, detect both
pleasant and potentially dangerous odors
– Spoiled food
– Mother’s perfume
• Many species communicate through
pheromones
– Chemicals, either hormones or scents, that allow
communication |
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Term
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Definition
– Composed of axons from hundreds of different
olfactory receptors |
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Term
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Definition
– Receive signals from the olfactory nerve and
transmits to the olfactory cortex in the brains’
frontal lobes |
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Term
| Taste signals are sent to |
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Definition
the medulla and pons in
the hindbrain and then on two pathways |
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Term
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Definition
| – Identification of tastes |
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Term
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Definition
– Generates unconscious reactions and learned
responses to tastes |
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Term
| Four Tastes of Gustatory Systems |
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Definition
• Sweet
• Sour
• Salty
• Bitter |
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Term
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Definition
involves the displacement of skin
– Varies widely across different parts of the body
– Very sensitive on hands and fingertips
• Pin prick hurts
– Little sensitivity on the buttocks
• Large needle hurts less than pin prick on the finger |
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Term
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Definition
– Difference between skin temperature and the
corresponding temperature on an object is the key |
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Term
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Definition
– Purpose of pain is to limit tissue damage
– No specific physical stimulus
– Free nerve endings transmit signals to the brain
when a cell is damaged |
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Term
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Definition
– Impacted by beliefs, expectations, emotional state
– Can control by changing source of pain or mental
attitude about pain
• E.g., childbirth is painful but rewarding |
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Term
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Definition
• Damage to sensory systems leads to
reorganization of those systems
• Phantom limbs involve p p eole who have lost an
arm or a leg but still sense its presence
• Amputees often experience phantom limbs for
some time after surgery |
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Term
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Definition
| • Regulate body position and movement |
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Term
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Definition
| – Provides information on the position of the body by sensing gravity and movement |
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Term
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Definition
– Provides information about the movement and
position of the limbs and other body parts
relative to one another |
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Term
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Definition
• Involves the organization and interpretation of
sensations
• Org g anizes sensations into meaningful units
• Interpretation of the organized sensations
– What does it mean |
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Term
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Definition
– Organizing sensations into meaningful shapes and
patterns |
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Term
Gestalt Principles of
Perceptual Organization |
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Definition
• The German term Gestalt means “whole” or
“form”
• Key is that the whole is greater than its parts |
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Term
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Definition
• Figure= Object they are viewing
• Ground= Background the object is embedded within
– Figure-ground for sound allows concentrating on single
voice in a crowded room |
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Term
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Definition
• We tend to group
similar elements
together |
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Term
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Definition
• We tend to group
together objects that
are close to one
another |
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Term
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Definition
• We organize stimuli
into continuous lines
or patters |
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Term
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Definition
• We tend to perceive
the simplest pattern
possible |
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Term
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Definition
• We tend to perceive
incomplete figures as
complete |
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Term
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Definition
• Matching current stimulus array against past
percepts in memory to determine identity |
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Term
| Recognition by Components: |
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Definition
– We perceive and categorize objects by breaking
them down into component parts and then matching
components and the way they are arranged against
similar “sketches” stored in memory
– Explains initial determination, not more subtle
distinctions we make later |
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Term
|
Definition
• The brain’s efforts to
organize sensations into
coherent percepts fails
• Organization lead to Organization lead to
perceptual
misinterpretations |
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Term
|
Definition
• The organization of perception in three
dimensions |
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Term
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Definition
| – Visual input integrated from both eyes |
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Term
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Definition
| – Visual input from one eye |
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Term
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Definition
– Slight difference in vision for each eye because eyes
are slightly different locations on face
– Greater difference for close objects |
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Term
| Retinal disparity interpreted by Binocular cells |
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Definition
– Some binocular cells respond most vigorously when
the same input arrives from each eye
– Other binocular cells respond most vigorously when
there is different input from each eye |
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Term
|
Definition
– When you observe an object close to you your
eyes come together (converge)
– When you observe more distant objects your
eyes diverge |
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Term
|
Definition
– When one object obstructs
another the blocked object
is perceived as more
distant |
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Term
|
Definition
– Objects farther away are
higher on one’s plane of
view and thus appear
higher up toward the
horizon |
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Term
|
Definition
– Textured surfaces
appear coarser at close
range and finer/more
densely packed at
great distance |
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Term
|
Definition
– Parallel lines appear to
converge in the
distance |
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Term
|
Definition
– The brain assumes light comes from above. Thus, we
interpret shading differently toward the top versus the
bottom of an object |
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Term
|
Definition
Aerial Perspective
– Distant objects appear fuzzier than closer ones |
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Term
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Definition
– We assume an object is its usual size even though it
appears smaller as distance increases |
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Term
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Definition
– When we look at two objects known to be of
similar size, we perceive the smaller object as
farther away |
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Term
|
Definition
– When we move images of closer objects sweep
across our field of vision faster than objects
more distant |
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Term
| Motion detectors in retina |
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Definition
sense movement
– Located outside fovea, in periphery of vision
– Ganglion cells carry signal to thalamus, then to
motor sensitive neurons in primary visual cortex |
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Term
|
Definition
• Two visual systems for processing movement
– Motion of the object being observed
• Ball coming toward catcher
– Motion of the person doing the observing
• Catcher moving to catch ball |
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Term
|
Definition
– We perceive objects (apple) as the same color
regardless on changes in illumination |
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Term
| Shape Constancy Shape Constancy |
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Definition
– We perceive objects as the same shape regardless of
sensory input (position or angle) |
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Term
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Definition
– Objects remain the same size regardless of distance
from the object such as a bridge on the highway |
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Term
| Perceptual Interpretation |
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Definition
• Process of generating meaning from sensory
experience
• Influenced by experience |
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Term
| • Gibson’s Theory of Direct Perception |
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Definition
– Sensory information intrinsically carries meaning
– Adaptive in nature |
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Term
| Visual Cliff experiments: |
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Definition
– Clear table with checkerboard beneath and another
checkerboard that appears to drop off on other side
– used to assess human infants’ depth perception
• Pre-crawling infants are curious, but crawling
infants are fearful of apparent “cliff |
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Term
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Definition
– Perception begins with multiple sensations and then
integrate the data in higher regions of the brain
– Inductive process |
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Term
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Definition
– Perception begins at higher regions of the brain
based on past experience as soon as sensations begin
coming in
– Deductive process |
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Term
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Definition
– The expectations or setting for perceptual
interpretation |
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Term
Perceptual Expectations
• Perceptual Set
– The expectations or setting for perceptual
interpretation
• Context influences how sensory stimuli are Context influences how sensory stimuli are
perceived
• Schemas are enduring beliefs and expectations
– Schemas are patterns of thinking about something
that enables us to have a sense of predictability
• Dogs bark, cats don’t bark |
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Definition
• Perceptual Set
– The expectations or setting for perceptual
interpretation
• Context influences how sensory stimuli are Context influences how sensory stimuli are
perceived
• Schemas are enduring beliefs and expectations
– Schemas are patterns of thinking about something
that enables us to have a sense of predictability
• Dogs bark, cats don’t bark |
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Term
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Definition
• We tend to perceive what we want to perceive
– Emotions and motivation influence processing of
sensory stimuli |
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