chapter 8-motion perception Flashcards Preview

Sensations and Perceptions > chapter 8-motion perception > Flashcards

Flashcards in chapter 8-motion perception Deck (53):
1

computation of visual motion

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

2

motion is

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

3

detecting movement (diagram) is what kind of circuit

neural motion detecting circuit

4

two input neurons with adjacent receptive fields feed into a

comparator neuron

5

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

different

6

for rightward motion, their responses arrive at the comparator ____

together

7

evidence for motion detectors in ___ recordings

single cell

8

evidence for motion detectors because

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

9

direction selectivity

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

10

MT

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

11

motion after effect

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

12

what accounts for the motion after effect

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

13

with stationary pattern, is there motion seen

no, only moderate activity

14

with motion in one direction, what are the neurons doing

neurons are selective for that direction, winning but fatiguing

15

after adaptation and in presence of stationary pattern, what happens

perceive motion in opposite direction

16

retinal image motion comes from what

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

17

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

displacement on the retina

18

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

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

19

observer motion

move eye/head/body and retinal image changes

20

optic flow

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

21

eye movement commants

motor system tells eyes to change position

22

saccadic suppression

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

smooth pursuit

eye smoothly follow a moving target

24

saccade

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

vergence

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

26

reflexive

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

27

mystagmus

eye jitters

28

optokinetic nystagmus

jerk in the direction of motion when trying to fixate

29

real movement

continuous change in position in a natural image

30

apparent movement

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

31

distance time trade off

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

32

receptive field size grows as you get __ in visual system

higher up

33

good apparent movement is

indistinguishable from real movement

34

cortical direction selective cells respond to

apparent movement

35

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

excites, same

36

the aperture problem

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

aperture

opening that allows partial view of an object

38

what cells have the aperture problem

V1

39

with aperture, ___ is ambiguous

local motion

40

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

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

41

combining info from different apertures happens where

MT

42

biological motion

pattern of movement of living things

43

tau

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

44

distinctions between processes

short range vs long range
first vs second order
feature tracking

45

first order

change in position of luminance defined objects

46

second order

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

47

feature tracking

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

48

some neurons are ___ selective motion detectors

directionally

49

brain uses several strategies to distinguish between __ and __ motion

object and observer

50

___ motion can be explained by responses in neural motion detectors

apparent

51

issues about ambiguous local motions are solved with ____

global motion detectors

52

evidence indicates that 2 or more subsystems mediate motion perception

2

53

correspondence problem

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