Chapter 8: Motion Perception

Question 1

motion aftereffect (MAE)

Answer 1

The illusion of motion of a stationary object that occurs after prolonged exposure to a moving object.

Question 2

apparent motion

Answer 2

The illusory impression of a smooth motion resulting from the rapid alternation of objects that appear in different locations in rapid succession.

Question 3

correspondence problem

Answer 3

In motion detection the problem faced by the motion detection system of knowing which feature in frame 2 corresponds to a particular feature in frame 1.

Question 4

aperture problem

Answer 4

The fact that when a moving object is viewed through an aperture (or a receptive field), the direction of motion of a local feature or part of the object may be ambiguous.

Question 5

aperture

Answer 5

An opening that allows only a partial view of an object.

Question 6

middle temporal area (MT)

Answer 6

An area of the brain thought to be important in the perception of motion.

Question 7

interocular transfer

Answer 7

The transfer of an effect (such as adaptation) from one eye to the other.

Question 8

first-order motion

Answer 8

the motion of an object that i defines by changed in luminance.

Question 9

luminance-defined object

Answer 9

AN object that is delineated by changes in luminance.

Question 10

second-order motion

Answer 10

The motion of an object that is defined by changes in contrast or texture, but not by luminance.

Question 11

texture-defined (contrast-defined) object

Answer 11

An object that is defined by changes in contrast, or texture, but not by luminance.

Question 12

optic array

Answer 12

the collection of light rays that interact with objects in the world that are in front of a viewer

Question 13

optic flow

Answer 13

the changing angular positions of points in a perspective image that we experience as we move through the world.

Question 14

focus of expansion

Answer 14

The point in the center of the horizon from which, when we’re in motion, all points in the perspective image seem to emanate. The focus of expansion is one aspect of optic flow.

Question 15

biological motion

Answer 15

The pattern of movement of living beings

Question 16

time to collision (TTC)

Answer 16

The time required for a moving object to hit a stationary object. TTC = distance/rate.

Question 17

tau

Answer 17

Information in the optic flow that could signal TTC without the necessity of estimating either absolute distances or rates. The ratio of the retinal image size at any moment to the rate at which the image is expanding is tau, and TTC is proportional to tau.

Question 18

smooth pursuit

Answer 18

a type of voluntary eye movement in which the eyes move smoothly to follow a moving object.

Question 19

superior colliculus

Answer 19

A structure in the midbrain that is important in initiating and guiding eye movements.

Question 20

microsaccade

Answer 20

An involuntary, small, jerklike eye movement.

Question 21

vergence

Answer 21

A type of eye movement in which the two eyes move in opposite directions; for example, both eyes turn toward the nose (convergence) or away from the nose (divergence)

Question 22

saccade

Answer 22

A type of eye movement, made both voluntarily and involuntarily, in which the yes rapidly change fixation from one object or location to another.

Question 23

reflexive eye movement

Answer 23

A movement of the eye that is automatic and involuntary.

Question 24

saccadic suppression

Answer 24

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

Question 25

comparator

Answer 25

An area of the visual system that receives one copy of the command issued by the motor system when the eyes move (the other copy goes to the eye muscles). The comparator compares the image motion signal with the ye motion signal and can compensate for the image changes caused by the eye movement.

Question 26

akinetopsia

Answer 26

A rare psychological disorder in which the affected individual has no perception of motion.