Sensation And Perception Ch. 7 Motion Perception

Front 1

akinetopsia

Back 1

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

Front 2

aperture

Back 2

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

Front 3

aperture problem

Back 3

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.

Front 4

apparent motion

Back 4

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

Front 5

biological motion

Back 5

The pattern of movement of living beings (humans and animals).

Front 6

comparator

Back 6

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

Front 7

correspondence problem (motion)

Back 7

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

Front 8

first-order motion

Back 8

The motion of an object that is defined by changes in luminance. Compare second-order motion.

Front 9

focus of expansion

Back 9

The point in the center of the horizon from which, when you are in motion (e.g., driving on the highway), all points in the perspective image seem to emanate. The focus of ex­pansion is one aspect of optic flow.

Front 10

interocular transfer

Back 10

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

Front 11

luminance-defined object

Back 11

An object that is defined by changes in luminance.

Front 12

middle temporal lobe (MT)

Back 12

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

Front 13

motion aftereffect (MAE)

Back 13

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

Front 14

optic array

Back 14

The term coined by J.J.Gibson to describe the collection of light rays that interact with objects in the world in front of a viewer.

Front 15

optic flow

Back 15

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

Front 16

saccade

Back 16

Rapid movement of the eyes that changes fixation from one object or location to another.

Front 17

saccadic suppression

Back 17

The reduction of visual sensitivity that occurs when one makes a saccadic eye movement. Saccadic suppression eliminates the smear from retinal image motion during an eye movement

Front 18

second-order motion

Back 18

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

Front 19

smooth pursuit

Back 19

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

Front 20

superior colliculus

Back 20

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

Front 21

tau (τ)

Back 21

Information in the optic flow that could signal TTC (time to collision) 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.

Front 22

texture-defined (contrast-defined) object

Back 22

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

Front 23

time to collision (TTC)

Back 23

The time required for a moving object (such as a cricket ball) to hit you in the head. TTC = distance/rate.

Front 24

vergence

Back 24

A type of eye movement in which the two eyes move in opposite directions (e.g., both eyes turn toward the nose [convergence] or away from the nose [divergence]).