Lec. 11 (vision) Flashcards by Zoe Channel

how do we construct our representations of the external world?

sensation + perception

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DETECT physical energy (a stimulus) from the environment and convert it into neural signals; processing external info inside our brain; raw data; BOTTOM-UP process

sensation

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when we select, organize, and INTERPRET our sensations; adding meaning to our thoughts; separate objects and thoughs; TOP-DOWN process

perception

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sensation is a ________ process and perception is a _________ process

bottom-up; top-down

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T/F: sensation and perception occur at the same time in our brains

true

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which process is determining the difference between the computer screen and the wall behind it?

perception

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sensation (bottom-up processing): analysis of the stimulus begins with the ______ ______ and works up to the level of the brain and mind

sense receptors

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perception (top-down processing): information processing guided by higher-level _______ _______ as we construct perceptions, drawing on our _______ + ________

mental process; experiences + expectations

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during perception, we include ______ ______ into our thoughts

missing info

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our sensory (bottom-up) and perceptual (top-down) processes work together to help us sort out _______ images

complex

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light’s _____ ______ are perceived in specific ways (color and brightness)

physical properties

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physical property of light that determines HUE (color) of light

wavelength

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physical property of light that determines the INTENSITY (brightness) of light

amplitude

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only 2 properties of light =

wavelength (color) + amplitude (brightness)

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wavelength of light is measured in ______ or ______

meters or nanometers

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short wavelength = which color?

violet

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long wavelengths = which color?

red

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short wavelengths that show violet are around ______ nm

400 nm

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long wavelengths that show red are around ______ nm

700 nm

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visible wavelength range =

400 - 750 nm

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power or intensity of the radiant energy; the HEIGHT of the wave

amplitude

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the higher the amplitude, the _____ the light

brighter

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jelly-like, transparent fluid inside of the eyeball

vitreous humor

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adjustable opening where light enters the eye; a HOLE

pupil

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colored muscle surrounding the pupil, controls the aperture of the pupil; responds to light intensity or internal states; UNIQUE like fingerprints

iris

outer, protective covering of the eye

cornea

if you are RELAXED, your pupil _______

enlarges (opens up)

if you are CONCENTRATED, your pupil _______

gets smaller (clamps up)

if your pupil is unresponsive to light and does not change size, this can indicate what?

brain damage

pupil size is dependent on what 2 things?

amount of light + internal states/environment (ex: the task at hand)

what controls the size of the pupil?

iris

focuses light onto the retina; small muscles allow it to change shape to focus light -- ACCOMODATIONS

lens

looking at something close and then far away; involuntary

accomodation

which part of the eye is responsible for accomodation?

the lens

the _______ of the lens is important for its function

flexibility

the flexibility of your lenses ______ with age and you can't see close or far away as quickly (aka accommodation SLOWS down)

decreases

when lens get cloudy (cataracts), you can get surgery to replace them with a _______ version

plastic

a layer of photo-sensitive cells in the back surface of the eye ball

retina

the retina _______ photons into chemical changes that result in neural impules

transduces

converting light energy into chemical energy

transduction

a central area of the retina that contains only CONES

fovea

two main types of RECEPTORS/cells of the retina:

- cones - rods

the rest of the retina besides the fovea contains ______

rods

the fovea is located where in the eye?

directly in the back of the eye, perpendicular

site of transduction =

retina

what causes your blind spot?

tail ends of neurons in retina going to optic nerve

vision process (4):

1) light reaches the rods and cones 2) chemical reactions activate the bipolar cell layer 3) bipolar cells activate the ganglion cell layer 4) the axons of the ganglion cells bunch up to from the optic nerve

3 layers of the retina:

- ganglion layer - bipolar cell layer - photoreceptor layer

only layer of the retina that is LIGHT SENSITIVE

photoreceptor layer

which layer of the retina has axons/tails that bunch up to create the optic nerve?

ganglion cell layer

highly aggregated (summarized) information from thousands of visual receptors are fed into the _______

ganglion

ganglion "sees" a small part of the world, known as their "__________ ________"

receptive field

types of activity of the ganglion (3):

- high - medium - low

type of ganglion activity: light on center and surround

medium

type of ganglion activity: light on center; dark on surround

high

type of ganglion activity: dark on BOTH center and surround

low

the ganglion has highly _______ vision

abstracted (sees brightness, edge, light, and dark)

carries signal from the eye to the brain

optic nerve

point where the optic nerve leaves the eye

blind spot

central point in the retina around which the eye's cones cluster

fovea

which one do we have more of --- rods or cones?

rods

number of rod receptors in our eyes =

~120 million

number of cones in our eyes =

~6 million

type of receptor: distributed ALL over the retina; detects black, white, grays

rods

type of receptor: concentrated on fovea; function in bright light conditions

cones

type of receptor: primarily responsible for PERIPHERAL vision and vision in the DARK

rods

type of receptor: primarily responsible for detection of DETAIL and COLOR

cones

T/F: you really don't have color in your peripheral vision; top-down processing (perception) just fills it in

true

to find a DIM star, you should find it in your _______ vision

peripheral (disappears when you look right at it)

sensory switchboard; has left and right lateral geniculate nuclei (LGN)

thalamus

where L and R hemispheres of vision cross

optic chiasm

in journey from retina to brain, information is _______ and _____ many times, at all levels

processed and abstracted

nerve cells in the visual cortex respond to specific features, such as edges, angles, and movement

feature detection

do we have brain tissue devoted to FASCIAL recognition?

yes

specific combinations of TEMPORAL lobe activity occur as people look at shoes, faces, chairs, and houses

shape detection

processing of several aspects of the stimulus simultaneously; brain divides a visual scene into subdivisions such as color, depth, form, movement, etc.

parallel processing

theories of COLOR vision (2):

1) tri-chromatic theory of color vision 2) opponent-process theory of color vision

theory of color vision: any color can be produced by mixing pure versions of BLUE, GREEN, and RED light in different amount

tri-chromatic theory of color vision

tri-chromatic theory of color vision says we have three types of ______

cones

3 sub-types of cones according to tri-chromatic theory of color vision:

- red cones - blue cones - green cones

genetic disorder in which people are blind to green or red colors; SUPPORTS the trichromatic theory

color blindness

fcolor blindness ______ the trichromatic theory

supports (ie. cant see red? red cones are working)

the trichromatic theory cannot explain some quirks of color vision, such as _________

afterimages

problem with trichromatic theory: red-green color blind people can see ______ -- shouldn't be possible bc it seems to be a pure color like R, G, and B

yellow

theory of color vision: visual elements sensitive to color are grouped into three pairs; the members of each pair OPPOSE/INHIBIT each other

opponent-process theory of color vision

3 pairs of opponent-process theory:

- red-green - blue-yellow - black-white

opponent-process theory of color vision explains the phenomenon of what 2 things?

- complimentary colors - after images

according to the opponent-process theory of color vision, if red is stimulated/shown, your ability to see ______ is inhibited

green (when red is taken away, green shoots up in afterimage)

which color vision theory is correct?

both (color processing happens in stages/levels)

TWO color processing stages/levels

- photoreceptor level - ganglion cell layer

color processing level: at this layer, you have 3 types of cones -- TRICHROMATIC THEORY

photoreceptor layer

color processing level: at this layer, there are receptors paired among complimentary colors -- OPPONENT-PROCESS THEORY

ganglion cell layer

which layer of the retina sends visual info to the occipital lobe/visual cortex

ganglion cell layer

the photoreceptor layer acts as "________" while the ganglion cell layer acts as the "_______"

employees; VP