Chapter 8

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

interocular transfer

Answer 2

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

Question 3

middle temporal area (MT)

Answer 3

An area of the brain thought to be important in the perception of motion; also called V5 in humans.

Question 4

apparent motion

Answer 4

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

Question 5

correspondence problem

Answer 5

In reference to 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 6

aperture problem

Answer 6

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

Question 7

aperture

Answer 7

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

Question 8

first-order motion

Answer 8

The motion of an object that is defined by changes in luminance.

Question 9

luminance-defined object

Answer 9

An object that is delineated by differences in reflected light.

Question 10

second-order motion

Answer 10

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

Question 11

texture-defined/contrast-defined object

Answer 11

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

Question 12

akinetopsia

Answer 12

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

Question 13

double dissociation

Answer 13

The phenomenon in which one of two functions, such as first- and second-order motion, can be damaged without harm to the other, and vice versa.

Question 14

optic array

Answer 14

The collection of light rays that interact with objects in the world that are in front of a viewer (coined by J.J. Gibson)

Question 15

optic flow

Answer 15

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

Question 16

focus of expansion

Answer 16

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

Question 17

time to collision (TTC)

Answer 17

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

Question 18

tau

Answer 18

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 19

biological motion

Answer 19

The pattern of movement of living beings.

Question 20

smooth pursuit

Answer 20

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

Question 21

superior colliculus

Answer 21

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

Question 22

microsaccade

Answer 22

An involuntary, small, jerk-like eye movement.

Question 23

vergence

Answer 23

A type of eye movement in which the two eyes move in opposite directions.

Question 24

convergence

Answer 24

both eyes turn toward the nose

Question 25

divergence

Answer 25

both eyes turn away from the nose

Question 26

saccade

Answer 26

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

Question 27

reflexive eye movement

Answer 27

A movement of the eye that is automatic and involuntary.

Question 28

optokinetic nystagmus (OKN)

Answer 28

A reflexive eye movement in which the eyes will involuntarily track a continually moving object.

Question 29

saccadic suppression

Answer 29

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 30

efference copy / corrollary discharge signal

Answer 30

The phenomenon in which outgoing (efferent) signals from the motor cortex are copied as they exit the brain and are rerouted to other areas in the sensory cortices.

Question 31

comparator

Answer 31

An area of the visual system that receives one copy of the command issued by the motor system when the eyes move; compares the image motion signal with the eye motion signal and can compensate for the image changes caused by the eye movement.