Unit 3: Sensation and Perception Flashcards
prosopagnosia
face blindness
sensation
process by which sensory receptors and the nervous system receive + represent environmental stimuli
perception
process bywhich sensory info is organized + interpreted so that we can recognize meaningful objects + events
top-down processing
info processing starting w/ higher level mental processes in the brain- constructs perceptions from sensory input
pereptions over sensation
occurs when we bring our expectations * prior knwoeldge to an enviro or stiatuion
bottom-up processing
starts at sensory receptors + works up to brain’s integration of sensory info
sensation over perception
occurs when we are unfaimilar with an enviro or situation
selective attention
focusing of conscious awareness on a particular stimulus
encompasses cocktail party effect, inattentional blindness, and change blindness
cocktail party effect
form of selective attention
pick out one voice from a sea of voices
inattentional blindness
form of selective attention
failure to see visible object when attention is directed elsewhere
change blindness
form of selective attention
failure to notice changes in environment
transduction
process of converting one form of energy (stimuli) into another that the brain can use (neural impulses)
How do our sensory systems function?
(rtd)
By:
receiving sensory stimuli through special receptors,
transforming stimuli into neural impulses, and
delivering neural info to the brain
psychophysics
study of relationship between physical characteristics of stimuli and our psychological experience of them
absolute threshold
minimum stimulus energy required to detect stimulus 50% of the time
ex:
specialist sends diff tones to determine pt where for any freq you hv that rate of detection
signal detection theory
assumes detection depends on alertness, not necessarily the absolute threshold
ex: a solider more likely to hear a noise at night while standing guard than a civilian is to hear that same noise when they’re watching tv at home
Does subliminal advertising work?
subliminal = below absolute threshold for conscious awareness
Yes if based on priming - we evaluate stimuli even when not consciously aware of it
No if just subliminal messaging to change our behavior - research shows it performs the same as a placebo
priming
unconscious activation of certain associations to predispose one to a particular perception / memory / response
difference threshold
min difference between 2 stimuli required for a 50% detection rate of that difference
once met, we experience it as a JND (just noticeable difference)
Weber’s Law
disscovered by Ernst Weber in late 1800s
for avg person to perceive a difference between 2 stimuli, they have to differ by a minmum constant PERCENTAGE, not amount.
ex: light, 8%. tones, 0.3%.
perceptual set
mental predisposition to perceive on ethings and not another - influences how we use top-down processing to interpret ambiguous situations
How do context, motivation, and emotion affect our perceptions?
ESP
Does it exist?
parapsychology
What does our perception of color depend on?
module 18
wavelength (distance from one wave peak to another … shorter wavelengths = more blue/violet = high frequency. long wavelengths = more red = low frequency)
How does light pass through the eye?
- Cornea
- Pupil
- Iris
- Lens
- Retina
a. rods/cones
b. bipolar cells
c. ganglion cells
d. optic nerve
e. thalamus
f. visual cortex
CPILR
cornea
clear, protective outer layer covering the pupil + iris
bends light to provide focus
pupil
small adjustable opening in the center of the eye through which light enters (after it hits cornea)
iris
ring of colored muscle tissue - dilates or constricts in response to light intensity, emotional stimuli
surrounds pupil + controls its size
lens
transparent structure behind the pupil that changes shape to focus images on the retina (in a process called accomodation)
The amount of light entering the eye is regulated by:
iris
accomodation
the process by which the curvature and thickness of the lens change - helps eye focus on near / far objects
retina
multilayered tissue on eye’s sensitive inner surface
contains receptor rods + cones that process info + forward impulses to the brain, which doesn’t “see” the whole image but rather reassembles visual info into an image we perceive
objects within the retina
- fovea, rods, and cones
- bipolar cells
- ganglion cells
- optic nerve
- blind spot
rods vs. cones
rods are used in peripheral, night, and grey scale vision
cones are used in fine detail and color vision - they cluster around the fovea
both convert light energy to neural impulses via transduction
upon hitting both, light triggers a photochemical reaction that activate the bipolar cells
fovea
central / focal point in the retina around which cones cluster
bipolar cells
activated by chemical reaction when light hits rods/cones
turns on ganglion cells by transmitting impulse from rods/cones to ganglion cells
ganglion cells
activated by bipolar cels
upon activation, their axons converge, forming the optic nerve
optic nerve
composed of the axons of ganglion cells
transmit impulses from eyes to thalamus (which sends to visual cortex)
blind spot
point where optic nerve leaves the eye
blind because no receptor cells are located there
Which two parts of the brain process vision?
thalamus
occipital lobe (visual cortex)
The fact that people who are color blind to red and green may still see yellow is most easily explained by:
opponent process theory
The ability to simultaneously recognize color, shape, size, and speed of an oncoming car best illustrates:
parallel processing
Young-Helmholtz Trichromatic theory
retina hosues 3 specific receptors responsible for perceiving color - red, green, blue. three colors combine to produce the other colors we see
helps explain color blindness
opponent process theory
color vision depends on three sets of opposing retinal processes: red/green, blue/yellow, black/white
helps explain afterimages - when one looks at an image for a long time, the color receptors for those colors weaken. when one looks away, opponent receptor will fire, leading to a negative afterimage.
gestalt psychology
the study of the organized whole
idea that perceptual organization considers more thant he components of an image - we tend to integrate them into meaningful wholes
Name the gestalt principles.
figure-ground
grouping-proximity
grouping-similarity
grouping-continuity
grouping-closure
Similarity, proximity, closure, continuity, connectedness
binocular vs monocular cues
binocular: depth cues that depend on both eyes to function
monocular: available to each eye separately
retinal disparity
finger sausage
A binocular cue for perceiving depth that compares the retinal images from both eyes.
b/c eyes are more than 2 inches apart, retinas perceive differently. closer object = greater retinal disparity (difference between images cast on retina)
sausage finger: 2 index fingers closely in front of eyes creates perception of floating finger sausage
visual cliff
lab experiment used to test depth perception in infants
appears as steep drop-off (but actually just sturdy glass)
mothers try to coax infants across - if refused, indicates they can perceive depth
figure-ground
organization into thing that stands out (figure) from its surroundings (ground)
What’s the pathway from eye to brain?
retina, optic nerve, thalamus, occipital lobe
Because Francisca, Stephanie and Naomi were all sitting together, behind the same bowling lane, Gavin perceived that they were all members of the same bowling team. This best illustrates the organizational principle of:
proximity
As the farmer looked across her field, the parallel rows of young corn plants appeared to converge in the distance. This provided her with a distance cue known as:
linear perspective
gestalt: proximity
grouping nearby things that are close together
ex: ppl sitting near each other behind the payton basketball team - we assume they’re payton supporters
gestalt: similarity
grouping things that appear similar - we also think they have the same function
ex: four columns of circle, triangle, circle, circle - we will group them into row of triangles and rows of circles
gestalt: continuity
things perceived as smooth, continuous patterns (not discontinuous objects)
ex: semicircles split up by horizontal line perceived as smooth sine curve on top of line
gestalt: closure
fill in gaps to create complete, whole object
ex: discontinous circles - we perceived as white triangle
depth perception
the ability to see objects in 3D despite 2D retinal image projection
allows us to judge distance
list of monocular depth cues
relative height
relative motion
relative size
linear perspective
interposition
light and shadow
relative height (monocular depth cue)
objects higher in our FOV perceived as further away
example: TBD
relative motion (monocular depth cue)
objects appear to move, even if stable, if you are moving
e.g. on train - if you look at house, surroundings appear faster
farther an obj is from fixation pt, faster it seems to move (horizon objs look faster than objs closer)
relative size (monocular depth cue)
if 2 objects are actually similar in size, the one that casts a smaller retinal image is one perceived as further away
linear perspective
parallel lines appear to meet in the distance
e.g. road
interposition
if one object is partially obstructing another, it’s perceived as closer than the object it’s obstructing
e.g. two deer, one ‘in front’ of other
light and shadow
shading = perceived as depth
ex: little dark circle on big light circle looks like a dent
perceptual constancy
not perceiving change in an object even as illuination/retinal imaging change
happens because we compute light reflect by an object relative to the objects around it
lightness constancy
perceiving constant brightness even as illumination varies
depends on relative luminance: amount of light on object relative to its surroundings
color constancy
perceiving familiar objects in a consistent color even as wavelengths altered
e.g. tomato appears red in salad even when wavelengths of light bouncing off indicate it should be perceived as blue
What has research on restored vision, sensory restriction, and perceptual adaptation showed us about the effects of experience on perception?
sensory restriction: if no opp to develop perception, no perception dev. if a cat deprived of horizontal lines, when released into the wild, it has difficulty perceiving horizontal bars.
restored vision: blind adults with restored sight unable to recognize faces
perceptual adaptation: we have visual ability to adjust to artificially displaced visual field :)
feature detectors
specialized neurons in the visual cortex that respond to particular lines, angles, edges, and movement
feature of parallel processing
helps us piece together perception into whole
McGurk effect
module 20
multisensory illusion, demonstrates that accurate perception of sound info depends on multiple senses (multimodal perception)
senses didn’t evolve independently but work together
How does a sound wave travel to the brain?
sound wave –> eardrum vibrates –> middle ear channels vibrations to oval window of —> cochlea’s vibrations jostles fluid which ripples and the –> basillar membrane’s hair cells bend which triggers adjacent nerve cell axons to converge forming the —> auditory nerve –> thalamus –> temporal lobe (BRAIN)
sw–eardrum–midear (cochlea, BM) –aud nerve — thalamus – temp lobe
What do the properties of a sound wave depend on?
frequency of the wave (short wavelength = high frequency = high pitch)
amplitude of the wave (big amplitude = loud sounds)
outer ear
visible part of ear + auditory canal
funnels sound to middle ear (eardrum in particular)
eardrum
tight membrane that vibrates upon sound waves striking it
middle ear
chamber between eardrum + cochlea,, contains anvil, hammer, and stirrup ones that transfer vibrations from eardrum to cochlea oval window
cochlea
coil/snail shaped fluid-filled tube inside inner ear
when oval window vibrates, jostles fluid inside, which causes ripples in the basilar membrane
basilar membrane
membrane within cochlea that contains hair cells
jostling of chocalea oval window causes ripples, which bends hair cells
hair cells
sensitive stalks in basilar membrane
transduct vibrations of sound waves into neural impulses BECAUSE triggers adjacent cells’ axons to converge, forming auditory nerve
auditory nerve
formed by converging axons of nerve cells adjacent to hair cells in basilar membrane
passes sound wave as neural impulse from ear to thalamus to temporal lobe
sensorineural vs conduction hearing loss
sn = nerve deafness caused by damage to hair cell receptors in cochlea’s basilar membrane OR the auditory nerve (usually caused by prolonged exposure to loud sounds)
cd = damage to mechanical system that sends sound waves to cochlea (less common)
Why is it important that we have two ears that are apart from each other?
helps us localize sound
sounds that reach one ear faster than the other basically send their location to the brain
even the differences of 1/100,000 seconds helps us localize
place theory
explains how we hear high pitches sounds
cochlea vibrates in certain places depending on pitch (if that place is stimulated, it’s pitched this way - high pitch = near beginning of cochlea)
PROBLEM: low pitched sound waves not easily localized….
frequency theory
explains how we hear low pitched sounds by measuring rate of neural impulses traveling up auditory nerve
slower impulses = lower frequencies, faster = higher.
PROBLEM: super high pitches are at frequencies too high for neural impulses to accurately capture (neuron refractory period).
volley principle
in frequency theory, helps us explain how we hear super high pitches
because neurons have a refractory period, they work on a volley to process highest pitched sound waves that’re too high for neural impulses to accurately rep with one neuron alone
cochlear implants
translate sounds into electric signals that cochlea converts into perception
How do we sense touch?
module 21
Based on four sensations of pressure, warmth, cold, and pain
all touch based on this (cold+pressure=wet, cold+warm=hot)
BUT body responds differently depending on coggntive awareness (different reaction depending on what you believe is happening)
biopsychosocial theory of pain
pain interpreted through variety of factors and explains how same pain experienced differently depending on context
bio: nocireceptors detect damage to body systems
psycho: meaningful counterpart to pressure
social: promotes connections in empathy + commiseration
How do we sense taste?
five main receptors: sweet, sour, salty, bitter, umami
it’s a chemical sense (along with smell)
follows sensory interaction: one sense affects another - taste of food interacts with smell + texture on the tongue to produce senses
How do we sense smell?
chemical sense (along with taste)
oderants enter thorugh nose –> olfactory bulb + nerve –> to brain (NOT THROUGH THALAMUS. close to hippocampus so memory closely connected w smell)
kinesthesia vs vestibular sense
kinesthesia: sense of our body part’s position (able to report exact position and orientation of limbs)
vestibular sense: monitors head and body position to control sense of balance (able to walk in a straight line) – sense sourced from hairlike receptors in vestibular sacs in the inner ear
embodied cognition
influence of bodily sensations, gestures, and other states on cognitive preferences and judgments
gate control theory
theory of pain that the spinal cord has a neural “gate” that carries pain on small nerve fibers / allows them to be sensed BUT activation on larger fibers overrides and blocks pain signals
explains which pain messages received by brain via spinal cord … provides methods of controlling pain
What are methods of controlling pain?
endorphins = natural pain meds. Can be produced through drugs and exercise.
Other methods include surgery, acupuncture, thought distraction, and hypnosis.
