Ch6-Vision

Question 1

information is stored in terms of responses by neurons based on….

Answer 1

• which neurons respond
• their amount of response
• timing of their responses

Question 2

whatever excites a particular nerve establishes a special kind of energy unique to that nerve

Answer 2

law of specific nerve energies (influences what we perceive)

Question 3

Every stimulation of the optic nerve is perceived as light. This statement is an example of….

Answer 3

law of specific nerve energies

Question 4

center of the iris, where light enters

Answer 4

pupil

Question 5

rear surface of the eye, lined with receptors

Answer 5

retina

Question 6

located closer to center of the eye, receive messages from receptors at back of the eye (retina)

Answer 6

bipolar cells

Question 7

located still closer to center of eye, receive messages from bipolar cells

Answer 7

ganglion cells

Question 8

additional cells that get info from bipolar cells & send it to other bipolar cells, other amacrine cells, and ganglion cells

Answer 8

amacrine cells

Question 9

consists of ganglion cell axons, exits through the back of the eye and travels to brain

Answer 9

optic nerve

Question 10

has no receptors, where optic nerve leaves the back of the eye

Answer 10

blind spot

Question 11

why do we not notice our blind spot?

Answer 11

compensation between eyes

Question 12

in the retina, messages go from the back of the eye to _____

Answer 12

bipolar cells, then to ganglion cells, then exits through the optic nerve

Question 13

tiny area specialized for acute, detailed vision [packed tight with receptors]

Answer 13

fovea

Question 14

each receptor in ____ connects to a single bipolar cell, which in turn connects to a single ganglion cell, which has an axon to the brain

Answer 14

fovea

Question 15

ganglion cells in fovea of humans and primates

Answer 15

midget ganglion cells

Question 16

less detailed vision, allows for greater perception of much fainter light

Answer 16

peripheral vision

Question 17

abundant in periphery of retina, respond to faint light, not useful in bright light

Answer 17

rods (useful for night vision)

Question 18

abundant in & near fovea, less active in dim light, more useful in bright light, & essential for color vision

Answer 18

cones (useful for color vision)

Question 19

ratio of rods to cones in humans

Answer 19

cones are 1/20 as abundant as rods

cones provide 90% of brains input

Question 20

number of axons in optic nerve

Answer 20

average is 1 million

some have 2 to 3 times more; ex) tennis players show faster brain response to stimuli

Question 21

chemicals in both rods & cones that release energy when struck by light

Answer 21

photo-pigments

Question 22

we perceive color through relative rates of response by 3 kinds of cones, each kind maximally sensitive to a different set of wavelengths [short, medium, and long wavelengths]

Answer 22

Trichromatic (Young-Helmholtz) Theory

Question 23

perceive color in terms of opposites-the brain has a mechanism that perceives color on a continuum
Red to Green
Yellow to Blue
White to Black

Answer 23

Opponent-Process Theory

Question 24

afterimages occur due to ____

Answer 24

rebound effect from wavelengths being saturation while some are inhibited

Question 25

cortex compares info from various parts of the retina to determine the brightness & color for each area [includes color constancy]

Answer 25

Retinex Theory

Question 26

ability to recognize colors despite changes in lighting

Answer 26

color constancy

Question 27

perceive differences in brightness when there are none - perception of brightness of an object requires comparing it with other objects

Answer 27

brightness constancy

Question 28

some people lack 1 or 2 of the 3 types of cones; some people have 2 kinds of cones, but 1 is abnormal

Answer 28

color vision deficiency | [red-green most common]

Question 29

optic nerves from the 2 eyes meet at the _____

Answer 29

optic chiasm

Question 30

most ganglion axons go to the optic nerve then the optic chiasm then the _____ [part of the thalamus]; special for visual perception, sends to thalamus & occipital cortex

Answer 30

lateral geniculate nucleus

Question 31

reduction of activity in one neuron by activity in neighboring neurons; heightens contrast to emphasize borders of objects

Answer 31

lateral inhibition

Question 32

part of the visual field that excites or inhibits it [what excites the cell in the outside world]; point in space from which light strikes the cell

Answer 32

receptive field

Question 33

3 categories of ganglion cells in primates

Answer 33

parvocellular neurons magnocellular neurons koniocellular neurons

Question 34

small cell bodies & small receptive fields - located mostly in or near fovea [highly sensitive to color & visual detail]

Answer 34

parvocellular neurons

Question 35

larger cell bodies & receptive fields & are distributed evenly throughout retina [highly sensitive to overall patterns & moving stimuli]

Answer 35

magnocellular neurons

Question 36

small cell bodies, but occur throughout the retina [have several functions & axons terminate in many different places]

Answer 36

koniocellular neurons

Question 37

cortical area where conscious visual perception occurs

Answer 37

V1

Question 38

responsible for first stage of visual processing; located in occipital cortex

Answer 38

primary visual cortex = V1 = striate cortex

Question 39

people with damage to area V1; people respond to visual info that they report not seeing

Answer 39

blindsight

Question 40

Hubel & Wiesel recorded from cells in brains of cats & monkeys and distinguished which types of cells in visual cortex?

Answer 40

simple, complex, & end-stopped (hypercomplex) cells

Question 41

has receptive field with fixed excitatory & inhibitory zones; most have bar-shaped or edge-shaped receptive fields

Answer 41

simple cells

Question 42

responds to pattern of light in a particular orientation anywhere within its large receptive field [sensitive to diagonal bars, esp. when moving]; located in v1 & v2, does not respond to exact location of stimuli

Answer 42

complex cells

Question 43

resembles complex cell, but has a strong inhibitory area at one end of its bar-shaped receptive field [responds provided the object does not cross a certain point in the visual field]

Answer 43

end-stopped (hypercomplex) cells

Question 44

neuron that indicates the presence of a particular feature [prolonged exposure to a given visual feature decreases sensitivity to that feature]

Answer 44

feature detector

Question 45

most neurons in visual cortex receive ______; input from both eyes

Answer 45

binocular input

Question 46

if each eye is alternately covered during the first few weeks of life, would the visual cortex still receive binocular input

Answer 46

no, most cortical neurons would respond to stimuli in each eye separately, not at the same time

Question 47

what happens if both eyes are kept shut for the first few weeks of life?

Answer 47

synapses are inhibited

Question 48

time period when experiences have particularly strong & enduring influence

Answer 48

sensitive period

Question 49

comparison of slightly different inputs from both eyes allows you to achieve _______

Answer 49

stereoscopic depth perception

Question 50

stereoscopic depth perception requires the brain to detect _______; the discrepancy between what the left & right eyes see

Answer 50

retinal disparity

Question 51

eyes do not point in same direction, both eyes are active, but no cortical neuron consistently receives messages from one eye that match the other eye

Answer 51

strabismus (lazy eye)

Question 52

about 70% of infants have _______, blurring of vision for lines in one direction [caused by asymmetric curvature of eye]

Answer 52

astigmatism

Question 53

if we compare receptive fields of two simple cells in primary visual cortex, how are they most likely to differ?

Answer 53

orientation of line that they respond to

Question 54

receives info from primary visual cortex (v1), processes it further, & transmits it to additional areas

Answer 54

secondary visual cortex (V2)

Question 55

visual pathway in parietal cortex; the "where" pathway - helps motor system locate objects [find objects & move towards them

Answer 55

dorsal stream

Question 56

what is damaged if people can tell what things are but not where they are

Answer 56

dorsal stream

Question 57

collection of visual paths in temporal cortex; the "what" pathway - identifying & recognizing objects

Answer 57

ventral stream

Question 58

what is damaged if people cannot describe what they are seeing

Answer 58

ventral stream

Question 59

as visual info goes from simple cells to complex cells to other brain areas, the receptive fields become more _____

Answer 59

specialized

Question 60

cells in _____ respond to identifiable objects; respond to what viewer perceived, not physical stimulus

Answer 60

inferior temporal cortex

Question 61

inability to recognize objects despite otherwise satisfactory vision, results from damage in temporal cortex

Answer 61

visual agnosia

Question 62

area that responds strongly to faces, much more than anything else [located in inferior temporal cortex]

Answer 62

fusiform gyrus

Question 63

inability to recognize faces, can distinguish gender & age but not recognize individual; occurs from damage to fusiform gyrus

Answer 63

prosopagnosia

Question 64

people with motion blindness have probably suffered damage to the

Answer 64

middle-temporal cortex [area v5]

Question 65

able to see objects but impaired at seeing whether they are moving or, if so, which direction & how fast

Answer 65

motion blindness

Question 66

decrease activity during voluntary eye movements

Answer 66

saccades

Question 67

some people are blind except for ability to detect which direction something is moving, which area is this due to

Answer 67

middle-temporal cortex and lateral geniculate nucleus