sensation and perception exam 2 review

why is color perception so important

it plays an important role in perceptual organization (hypothesized humans might’ve evolved color perception from foraging fruit), helps with recognizing and identifying objects, colors can cue emotions and facial expression

what did newton conclude about color and light

light in each part of the spectrum is defined by different physical properties, these differences result in the perception of different colors

what is selective reflection

some wavelengths are reflected off objects more than others which result in chromatic colors (blue, red, green, yellow)

what happens when light is reflected evenly across the spectrum

achromatic colors (black, white, grey)

what do reflectance curves show

the percentage of light reflected off different objects

what is selective transmission

only some wavelengths pass through the object (this creates colors of transparent things)

what do transmission curves show

the percentage of light transmitted at each wavelength, usually look similar to reflectance curves

what is subtractive color mixing

each pigment you add subtracts (absorbs) more wavelengths of light, leaving less to bounce back to your eyes. (ex: blue absorbs L wavelength, reflects S and M. yellow absorbs S wavelength, reflects L and M. green absorbs S and M, reflects only M. Both blue and yellow reflect M wavelength light, so only M wavelength light will be reflected, showing green)

what is additive color mixing

for light, mixing lights causes more wavelengths. (blue light is S wavelength light, yellow light is M and L wavelength light, the combination is S, M, L wavelength light, which makes white light)

what is the main difference between colors of light and colors of objects

colors of light are associated with wavelengths in the visible spectrum while colors of objects are associated with which wavelengths are reflected (for opaque objects) or transmitted (for transparent objects)

what does the trichromatic (young-helmholtz) theory state

color vision is based on three types of color receptors in the eye

what evidence supported the trichromacy theory

supported by color matching; reference color is shown to observer and the observer tries to match the color by adjusting proportions of different wavelengths

what is metamerism

two physically different stimuli that are perceptually identical. metamers are two lights that have different wavelength distributions but are perceptually identical

what is monochromacy

rare form of color blindness from the lack of functioning cones (only rods) so you view the world in shades of lightness (white, grey, black)

what is dichromacy

color deficiency resulting in having two types of cones

what is the opponent process theory

perception of color is determined by two opponent or opposite mechanism

what is psychophysical evidence for opponent-process theory

hue cancellation experiments. if blue-yellow is opponent process, mixing would cancel their colors. subjects cancelled out hues wiht their opposite to make a pure hue

what is physiological evidence for opponent process theory

discovery of opponent neurons in LGN gives neural evidence. 3 color related receptive fields: circular single opponent (m wavelengths excite center, L excites surround) circular double opponent (center M excite L inhibit. surround: l excite M inhibit) side by side single opponent (left, M excite L inhibit. right, M inhibit L excite)

what is color constancy

perceiving the color of objects as constant even under different amounts of light

why is color constancy impressive

the same object reflects different wavelengths depending on illumination

what is chromatic adaptation

prolonged exposure to a chromatic color decreases your sensitivity to that color

what is lightness constancy

perception of an objects lightness is constant across different illumination

what does the ratio principle say

your brain judges how light a surface is by comparing how much light it reflects off a surface to how much light is reflecting off of its surroundings. the perceived lightness is determined by this ratio of the light an object reflects and its surroundings

what are oculomotor cues

depth cues based on our ability to sense the position of our eyes and tension in our eye muscles (we literally feel it, created by convergence and accomodation)

what are monocular cues

depth cues based on visual information available to one eye (accommodation, pictorial cues, movement based cues)

what are pictorial cues

sources of depth info that can be depicted in 2D picture

what are the different kinds of pictorial cues

occlusion, relative height, familiar and relative size, perspective convergence, atmospheric perspective, texture gradient, shadows

what is occlusion

when one object is in front of another object, indicates that the hidden object is further away

what is relative height

objects near bottom of the picture tend to be closer, near top further away

what is familiar size

judgement of distance is based on the knowledge of the sizes of objects

what is relative size

if two objects are roughly the same in physical size the further one takes up less visual field

what is perspective convergence

old paintings, parallel lines in distance coverage as distance increases

what is atmospheric perspective

the further an object is the more air particles we have to look through

what is texture gradient

elements in texture gradient look smaller as distance increases

what are shadows

gives info about object location and enhances three dimensionality of objects

what are motion produced cues

monocular cues when moving that help us with depth perception (motion parallax, deletion and accretion)

what is motion parallax

nearby objects appear to move quickly past us but more distance objects appear to move slowly (used in video games and cartoons)

what is deletion and accretion

deletion is when a further object is covered by a nearer object and accretion occurs when a further object is not by the nearer object

why can we not rely on a single depth cue

each cue itself gives a “best guess” at object depth, they work best at different distances, together they give us a reasonable estimate

what are binocular cues

cues based on visual info from both eyes

what is stereoscopic depth perception

each eye gets different 2D viewpoints to make a 3D image

what is the story with Dr. Susan Berry

she has strabismus as a kid (misalignment of the eyes resulting in cross eyes), so when her good eye was looking at an object the other eye didnt. we visual system started to suppress the vision in her bad eye to avoid double vision, leading her one eye to dominate. she had decent depth perception from monocular cues and eventually was given exercises to coordinate both eyes

what is binocular disparity

the difference in images between the left and right eyes/retinas

what is absolute disparity

difference in position of an image on the left retina compared to the right retina

what is the angle of disparity

the amount of absolute disparity

how do you determine is absolute disparity is crossed or uncrossed (eyes to focus)

indicated whether the object is in front of or behind th ehoropter, a greater angle of disparity means the object is further away from the horopter

what is relative disparity

the difference between two objects absolute disparities

what is stereopsis

the impression of depth coming from binocular disparity (the ability to perceive the world in 3D and judge distance from other objects)

what are disparity selective cells

neurons in the visual cortex that respond best to objects with a specific amount of disparity, preferences in disparity can be measured by creating a disparity tuning curve

what is some evidence that says disparity selective neurons are responsible for steropsis

kittens raised without binocular vision have few disparity selective cells and perform worse on depth perception tasks, stimulating these nruons with microstimulation changes the perception of depth in monkeys

where can these disparity selective cells be found

V1, also in other areas of dorsal and ventral visual pathways

what is said about depth perception across different species

predators have stereoscopic vision because of the placement of the eye in front of their face, prey lack disparity for a wider field of view

what is size perception

the ability to perceive size is dependent on the ability to perceive distance

what is a visual angle

the angle of an object relative to the observers eye, tells us how large an object is on the retina

how is size constancy based on the size-distance scaling

S = K(R x D). S = objects perceived size, K a constant (ignore) ,R = size of retinal image, D = objects distance

what is an example of the size distance scaling formula

when a person walks away from you, D (their distance) increases while R (their size on your retina) decreases, resulting in the same S (perceived size)

what is the muller-lyer illusion

which line is longer? the same size but the right looks longer because of misapplied size constancy scaling: your brain uses the wrong distance cue, so it makes an object seem further away than it really is (or vice versa) so it scales the perceived size incorrectly

how does misapplied constancy scaling explain the ponzo illusion

converging lines on the railroad make the animal look furhter away, resulting in perception of the larger capybara on top

how does the Ams Room illusion work

the room is smaller on the left, peepholes remove the depth cues. the distance is the same for both people but the retinal size is different, resulting in perception of differently sized people

what are the functions of motion

detecting things, perceiving objects, perceiving events social perception (interactions with people involve movements), emotional perception

what are the differences between event and event boundaries

an event is a segment of time that is perceived to have a beginning and ending. an event boundary is the point one event ends and another begins. most event boundaries are tied to a change in action, more likely to indicate event boundary when there is a change in speed or acceleration in actors hands

what is illusory motion and what are the three types of it

perception of motion even though nothing is actually moving. apparent motion, induced motion, motion after effects

what is apparent motion

perceived movement even though nothing is actually moving (gestalt psych)

what is induced motion

when motion of one object causes nearby stationary objects to appear to move

what is motion aftereffects

when looking at a moving stimulus for too long it causes stationary stimulus to appear to move (waterfall illusion)

what was found about how the brain responds to real and apparent motion

the same brain area responds to both real and apparent motion, so thats why they both look like motion

what is the corollary discharge theory

motion perception is determined if a brain structure called the compactor receives either: movement of the retinal image (image displacement signal, IDS) or signals that indicate movement of the eyes (corollary discharge signal, CDS). Either just the eyes move or the retinal image moves

what happens if the compactor receives both the image displacement signal and the corollary discharge signal at the same time

no motion perception

what are reichardt detectors

a hypothetical neural circuit with two neurons that send their signal to an output unit. (Ex: A and B send their signals to output unit, but there is a delay unit that slows A signal to output). both signals arrive at the same time resulting in strong firing and motion perception

what is the problem with reichardt detectors

they’re motion selective so you need to have sevrral circuits for all different directions

what is MT/V5

possibly a dedicated motion processing area in the brain. Evidence of lesioning MT reduced motion perception abilities, humans with Mt lesions cant see motion, deactivating human MT results in difficulty judging direction of motion, and stimulating different direction sensitive neurons shifts judgements of motion direction

what is the difference between overt and covert attention

overt is looking directly at attended object while covert is attention without looking (seeing something from the corner of your eye)

what is change blindness

difficulty detecting the difference in two images present back to back

what is inattentional blindness

a situation where the stimulus/object is not attended to, even when looking directly at it. we dont perceive that to which we do not attend. Ex: distracted driving

what is dichotic listening

an experimental procedure where you hear different stimuli in the left and right ears

what did cherry (1953) do

did dichotic listening but listeners reported little from the ignored channel but could detect their own name

what is the cocktail party effect

ability to focus on one conversation even though several are happening around you

what is broadbent’s filter models of attention

all stimuli is initially processed for basic physical features like color or shape, and then based on those features the filter sends only relevant stimuli for further information processing

what is spatial attention

attention to a specific location

what is a pre cueing paradigm and what does it show us

observers are told to fixate on a cross and the cue appears indicating where the target will be and the participants respond as quickly as possible. it showed faster reaction times in validly cued locations, so attention enhances processing efficiency

what is the feature integration theory

preattentive stage is when features like color and shape exist independently and the focused attention stage is when features are combined together (binding). searching for a single feature is quicker than two or more features together

what are saccades

a rapid eye movement from one fixation to the next

what are fixations

brief pauses of the eye between eye movements

what is visual salience

characteristics that cause stimuli to stand out and therefore attract attention (ex: bright colors, movement)

what is attentional capture

occurs when properties of the stimulus/object capture your attention against your will, analyzing characteristics make a saliency map

what are scene schemas

knowledge about what is contained in typical scenes so you look at things that seem out of place for longer

what are the benefits of attention

speed (faster at finding target), appearance (affects perceived contrast, attended objects are perceived as bigger, faster, and more richly colored)

what is the detection threshold

lowest concentration at which an odorant can be detected

are we better at identifying or detecting odors

detecting

what is the difference between humans and animals for odor perception

humans have smaller olfactory bulbs

what are olfactory receptor neurons (ORN)

sensory cells responsible for the sense of smell, in the olfactory epithelium, each cell has one receptor protein, around 400 different types of receptor proteins each sensitive to a specific type of odor

what is the olfactory bulb

brain structure below the frontal lobe that processes smell info using the glomeruli

what is the glomerulus

cluster of neurons that process smell, receive input from ORNs expressing a single receptor protein

what is the piriform/pyriform cortex

primary olfactory cortex, does not go through the thalamus

what other brain areas are involved in the process of smell

amygdala (emotional reactions to smell) and hippocampus (scent-related memories)

what explains odor-evoked autobiographical memories (OEAMs)

the close connection between the olfactory cortex and the amygdala/hippocampus

what are the 5 basic tastes and their functions

sweet (high nutritive and caloric value, automatic acceptance, sustaining life) bitter (automatic rejection, avoid harmful substances) sour (detecting acids in unripe or soiled food) salty (presence of sodium, important if sweating) savory/umami (associated with meat and protein)

what is the papillae/papilla

structures on the tongue including filiform, fungiform, foliate, circumvallate

what is the filiform

shaped like cones, appear on all the surface of the tongue, no taste buds

what is fungiform

shaped like mushrooms, tip and sides on tongue