chapter 8-motion perception

Question 1

computation of visual motion

Answer 1

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

Question 2

motion is

Answer 2

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

Question 3

detecting movement (diagram) is what kind of circuit

Answer 3

neural motion detecting circuit

Question 4

two input neurons with adjacent receptive fields feed into a

Answer 4

comparator neuron

Question 5

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

Answer 5

different

Question 6

for rightward motion, their responses arrive at the comparator ____

Answer 6

together

Question 7

evidence for motion detectors in ___ recordings

Answer 7

single cell

Question 8

evidence for motion detectors because

Answer 8

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

Question 9

direction selectivity

Answer 9

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

Question 10

MT

Answer 10

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

Question 11

motion after effect

Answer 11

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

Question 12

what accounts for the motion after effect

Answer 12

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

Question 13

with stationary pattern, is there motion seen

Answer 13

no, only moderate activity

Question 14

with motion in one direction, what are the neurons doing

Answer 14

neurons are selective for that direction, winning but fatiguing

Question 15

after adaptation and in presence of stationary pattern, what happens

Answer 15

perceive motion in opposite direction

Question 16

retinal image motion comes from what

Answer 16

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

Question 17

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

Answer 17

displacement on the retina

Question 18

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

Answer 18

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

Question 19

observer motion

Answer 19

move eye/head/body and retinal image changes

Question 20

optic flow

Answer 20

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

Question 21

eye movement commants

Answer 21

motor system tells eyes to change position

Question 22

saccadic suppression

Answer 22

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

Question 23

smooth pursuit

Answer 23

eye smoothly follow a moving target

Question 24

saccade

Answer 24

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

Question 25

vergence

Answer 25

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

Question 26

reflexive

Answer 26

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

Question 27

mystagmus

Answer 27

eye jitters

Question 28

optokinetic nystagmus

Answer 28

jerk in the direction of motion when trying to fixate

Question 29

real movement

Answer 29

continuous change in position in a natural image

Question 30

apparent movement

Answer 30

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

Question 31

distance time trade off

Answer 31

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

Question 32

receptive field size grows as you get __ in visual system

Answer 32

higher up

Question 33

good apparent movement is

Answer 33

indistinguishable from real movement

Question 34

cortical direction selective cells respond to

Answer 34

apparent movement

Question 35

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

Answer 35

excites, same

Question 36

the aperture problem

Answer 36

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

Question 37

aperture

Answer 37

opening that allows partial view of an object

Question 38

what cells have the aperture problem

Answer 38

V1

Question 39

with aperture, ___ is ambiguous

Answer 39

local motion

Question 40

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

Answer 40

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

Question 41

combining info from different apertures happens where

Answer 41

MT

Question 42

biological motion

Answer 42

pattern of movement of living things

Question 43

tau

Answer 43

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

Question 44

distinctions between processes

Answer 44

short range vs long range
first vs second order
feature tracking

Question 45

first order

Answer 45

change in position of luminance defined objects

Question 46

second order

Answer 46

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

Question 47

feature tracking

Answer 47

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

Question 48

some neurons are ___ selective motion detectors

Answer 48

directionally

Question 49

brain uses several strategies to distinguish between __ and __ motion

Answer 49

object and observer

Question 50

___ motion can be explained by responses in neural motion detectors

Answer 50

apparent

Question 51

issues about ambiguous local motions are solved with ____

Answer 51

global motion detectors

Question 52

evidence indicates that 2 or more subsystems mediate motion perception

Answer 52

2

Question 53

correspondence problem

Answer 53

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