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Sensations and Perceptions > chapter 8-motion perception > Flashcards

chapter 8-motion perception Flashcards

1
Q

computation of visual motion

A

motion detector; change in position, two adjacent receptors registers change, a delay accounts for change in time

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2
Q

motion is

A

change in position over time; activate receptive field at 2 different locations; 2 points in time in sequence

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3
Q

detecting movement (diagram) is what kind of circuit

A

neural motion detecting circuit

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4
Q

two input neurons with adjacent receptive fields feed into a

A

comparator neuron

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5
Q

during stimulation with motion, the two inputs are stimulated at ___ times

A

different

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6
Q

for rightward motion, their responses arrive at the comparator ____

A

together

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7
Q

evidence for motion detectors in ___ recordings

A

single cell

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8
Q

evidence for motion detectors because

A

many cells in cat and monkey visual cortex are direction selective, and respond very well to single direction

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9
Q

direction selectivity

A

responds well to 1 direction of motion much better than others, especially the opposite

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10
Q

MT

A

higher level motion selective area; depth; signal motion at larger distances; broader range, larger receptive field

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11
Q

motion after effect

A

adapt to direction/pattern of motion, perceive opposite afterwards; illusion of motion of a stationary object that occurs after prolonged exposure to a moving object; motion opponent process; interocular transfer

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12
Q

what accounts for the motion after effect

A

classic opponent process; motion is seen in te direction of the team that wins

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13
Q

with stationary pattern, is there motion seen

A

no, only moderate activity

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14
Q

with motion in one direction, what are the neurons doing

A

neurons are selective for that direction, winning but fatiguing

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15
Q

after adaptation and in presence of stationary pattern, what happens

A

perceive motion in opposite direction

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16
Q

retinal image motion comes from what

A

movement of object in the world or movement from observers head/body/eyes

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17
Q

moving car, stationary eye; leftward object motion results in right

A

displacement on the retina

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18
Q

stationary car, moving eye; when you shift your gaze,

A

location of objects move on retina, but occulomotor muscles signal eye movement

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19
Q

observer motion

A

move eye/head/body and retinal image changes

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20
Q

optic flow

A

changing angular positions of points in a perspective image that we experience as we move through the world; local velocities on the retina inform about motion; motion in depth, low velocities in the center, high velocities in the periphery

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21
Q

eye movement commants

A

motor system tells eyes to change position

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22
Q

saccadic suppression

A

the reduction of visual sensitivity that occurs when we make saccadic eye movements; eliminates the smear from retinal image motion during an eye movement

23
Q

smooth pursuit

A

eye smoothly follow a moving target

24
Q

saccade

A

rapid movement of the eyes that changes fixation from one object or location to another; jumps; 7-9 letters, 15 to the right and 3-4 to the left

25
Q

vergence

A

two eyes move in opposite directions, as when both eyes turn toward the nose

26
Q

reflexive

A

automatic and involuntary eye movements; eyes move to compensate for turning head/body so that eyes will stay focused on point

27
Q

mystagmus

A

eye jitters

28
Q

optokinetic nystagmus

A

jerk in the direction of motion when trying to fixate

29
Q

real movement

A

continuous change in position in a natural image

30
Q

apparent movement

A

discontinuous change in positions (series of locations); rapid alteration of objects

31
Q

distance time trade off

A

when objects are close together, can be fast flicker and see motion, as distance increase time delay must increase also

32
Q

receptive field size grows as you get __ in visual system

A

higher up

33
Q

good apparent movement is

A

indistinguishable from real movement

34
Q

cortical direction selective cells respond to

A

apparent movement

35
Q

apparent movement ___ neural detectors in the ___ way as real movement

A

excites, same

36
Q

the aperture problem

A

the fact that when a moving object is viewed through an aperture, the direction of motion of a local feature or part of the object may be ambiguous

37
Q

aperture

A

opening that allows partial view of an object

38
Q

what cells have the aperture problem

A

V1

39
Q

with aperture, ___ is ambiguous

A

local motion

40
Q

if motion within aperture is ambiguous, how does visual system correctly perceive overall motion

A

motion info from several local apertures (RFs) combines to determine the global motion; whichever possible motion is the same for all apertures

41
Q

combining info from different apertures happens where

A

MT

42
Q

biological motion

A

pattern of movement of living things

43
Q

tau

A

info in the optic flow that could signal time to collision without the necessity of estimating absolute distances or rates

44
Q

distinctions between processes

A

short range vs long range
first vs second order
feature tracking

45
Q

first order

A

change in position of luminance defined objects

46
Q

second order

A

object defined by changed in contrast or texture; focus of expansion

47
Q

feature tracking

A

motion perception for any stimulus where a change in position occurs, happens slowly

48
Q

some neurons are ___ selective motion detectors

A

directionally

49
Q

brain uses several strategies to distinguish between __ and __ motion

A

object and observer

50
Q

___ motion can be explained by responses in neural motion detectors

A

apparent

51
Q

issues about ambiguous local motions are solved with ____

A

global motion detectors

52
Q

evidence indicates that 2 or more subsystems mediate motion perception

A

2

53
Q

correspondence problem

A

in binocular vision the problem of figuring out which bit of the image in the left eye should be matched with which bit in the right eye; in motion detection, the problem faced by the motion detection system of knowing which feature in frame 2 corresponds to a feature in frame 1

Sensations and Perceptions (16 decks)

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