Chapter 8: Perceiving Movement

Question 1

akinetopsia

Answer 1

the difficulty or inability to perceive motion (rare condition)

Question 2

event

Answer 2

a segment of time at a particular location that is perceived by observers to have a beginning and an end

Question 3

event boundary

Answer 3

the point in time when each event ends and the next one begins

Question 4

when are event boundaries most likely to occur?

Answer 4

event boundaries are more likely to occur when there is a change in speed or acceleration of the movement

Question 5

functions of motion perception

Answer 5

• Detecting things (important for survival)
• Perceiving objects (we perceive things more accurately when an object is moving)
• Perceiving events
• Social perception (we use the characteristics of movement to interpret emotions)
• Taking action

Question 6

point-light walker

Answer 6

a method of presenting human motion by placing small lights on people’s joints and filming the patterns created when they move

Question 7

can people determine if people are acting socially based on point-light walkers?

Answer 7

participants were able to indicate if the people were interacting socially, but those with autism had more difficulties doing so.

Question 8

geometric shapes and movement perception experiment (Heider & Simmel, 1944)

Answer 8

showed an animated film to participants and asked them to describe what was happening. Although the characters were geometric objects, participants made up stories describing them as having feelings, motivations, and personalities

Question 9

real motion

Answer 9

the physical movement of a stimulus

Question 10

illusionary motion

Answer 10

the perception of the motion of stimuli that aren’t actually moving.

Question 11

3 types of illusionary movement

Answer 11

apparent motion, induced motion, and motion aftereffects

Question 12

apparent motion

Answer 12

an illusion of movement that occurs when two objects separated in space are presented rapidly, one after another, separated by a brief time interval

Question 13

induced motion

Answer 13

when the motion of one object causes a nearby stationary object to appear to move

Question 14

motion aftereffects

Answer 14

occur when a moving stimulus causes a stationary stimulus to appear to move

Question 15

waterfall illusion

Answer 15

the aftereffect of movement that occurs when one views a waterfall moving in one direction. Viewing the waterfall makes other objects appear to move in the opposite direction

Question 16

activation of real vs. apparent motion study

Answer 16

presented participants with either a control condition, a real motion display, or an apparent motion display and found that the activation associated with apparent and real motion were similar

Question 17

gibson’s ecological approach to motion perception

Answer 17

involves looking for information that is “out there” in the environment. focuses on how movement of what’s being observed changes in the optic array.

Question 18

optic array

Answer 18

the structure created by the surfaces, textures, and contours of the environment

Question 19

local disturbance

Answer 19

the covering and uncovering of the optic array

Question 20

global optic flow

Answer 20

the fact that everything moves at once in response to the movement of the observer’s eyes

Question 21

corollary discharge approach to motion perception

Answer 21

States that if the comparator receives just one signal (either image displacement or corollary discharge), movement will be perceived.

Question 22

3 types of signals according to the corollary discharge approach

Answer 22

image displacement, motor, and corollary discharge signals

Question 23

image displacement signal

Answer 23

occurs when an image moves across the retina

Question 24

motor signal

Answer 24

is sent from the motor area to the eye muscles to cause the eye to move

Question 25

corollary discharge signal

Answer 25

a copy of the motor signal that is sent to the eye muscles to cause the movement of the eye

Question 26

comparator

Answer 26

a brain structure hypothesized by the corollary discharge theory to determine whether movement will be perceived

Question 27

the Reichardt detector

Answer 27

A neural circuit proposed by Werner Reichardt in which signals caused by the movement of a stimulus across the receptors are processed by a delay unit and an output unit so that signals are generated by movement in one direction but not in the opposite direction

Question 28

output unit

Answer 28

compares the signal it receives from neurons A & B

Question 29

delay unit

Answer 29

slows down the signals from neuron A as they travel toward the output unit & multiplies the responses from A to B to create the movement signal that results in perception

Question 30

what type of signals does the Reichardt detector respond to?

Answer 30

movement from left to right

Question 31

does the Reichardt detector exist in other species?

Answer 31

Some more complicated versions of this circuit exist in other species, where neurons only fire to particular directions of motion

Question 32

medial temporal (MT) area

Answer 32

a brain area in the temporal lobe that is responsible for the direction and speed of object motion

Question 33

what happens when coherence is increased?

Answer 33

monkeys judged the direction of motion more accurately and MT neurons fired more vigorously. Demonstrates relationship C (the physiology perception relationship

Question 34

coherence

Answer 34

the degree to which the dots move in the same direction
(0%- you can’t detect a particular direction of movement; 100%- direction is easy to detect)

Question 35

what happens when the MT cortex is lesioned

Answer 35

there must be a higher coherence for monkeys to detect the direction of movement

Question 36

what happens when the MT cortex is deactivated using TMS?

Answer 36

participants experienced a form of akinetopsia

Question 37

Transcranial magnetic stimulation (TMS)

Answer 37

a method that temporarily disrupts the normal functioning of neurons by placing a magnetic coil above the skull to create a strong magnetic field. A series of electromagnetic pulses are then presented and if the behaviour is disrupted by the pulses, the disrupted area is involved in the behaviour

Question 38

what happens when the MT cortex is stimulated using microstimulation?

Answer 38

the perception of direction is shifted (ex. If neurons activated by downward motion are stimulated, the participant judges the original right motion as being downward and to the right)

Question 39

microstimulation

Answer 39

a method where neural activity is enhanced by lowering a small wire electrode into the cortex and passing a weak electrical charge through the tip of the electrode. The weak shock stimulates neurons near the tip, causing them to fire.

Question 40

Medial superior temporal (MST) area

Answer 40

involved in processing optic flow, locating moving objects, and reaching for moving objects

Question 41

biological motion

Answer 41

the self-produced motion of a person or other living organism

Question 42

implied motion

Answer 42

a situation in which a still picture depicts an action involving motion

Question 43

do areas of the brain that respond to motion respond to implied motion?

Answer 43

yes

Question 44

akinetopsia is also called

Answer 44

motion blindess

Question 45

what types of diseases lead to akinetopsia

Answer 45

Often occurs following traumatic brain injury, neurodegenerative diseases such as Alzheimer’s, Epilepsy, hallucinogen perception disorder (HPPD)

Question 46

brain damage in what areas cause akinetopsia?

Answer 46

Caused by damage to V5 medial temporal (MT) & temporo-parieto-occipital junction (TPJ), which are located along the dorsal stream

Question 47

patient LM

Answer 47

Suffered from akinetopsia after a bilateral brain hemorrhage

Question 48

patient SM

Answer 48

Couldn’t detect fear following bilateral amygdala damage

Question 49

Leaf-tail gecko & pygmy sea horse

Answer 49

difficult to detect because they camouflage, but once they start moving, you can detect it

Question 50

when do we perceive movement most accurately

Answer 50

when an object is moving

Question 51

what is one of the most important functions of movement?

Answer 51

it serves an organizing function, which groups smaller elements into larger units

Question 52

when do we perceive movement?

Answer 52

when there’s real or illusionary movement

Question 53

what’s a famous example of apparent movement?

Answer 53

the phi phenomenon

Question 54

phi phenomenon

Answer 54

apparent motion that is observed if two nearby optical stimuli are presented in alternation with a relatively high frequency

Question 55

what happens according to the corollary discharge theory if the eye follows a moving stimulus?

Answer 55

the corollary discharge signal is activated and movement is perceived

Question 56

what happens according to the corollary discharge theory if the eye is stationary but a stimulus is moving?

Answer 56

the image displacement signal is activated and movement is perceived

Question 57

what happens according to the corollary discharge theory if the eye moves across a stationary scene?

Answer 57

both the image displacement signal and the corollary discharge signal are activated and movement is not perceived