psych of perception chapter 8

Question 1

motion agnosia
akinetopsia

Answer 1

when cortex involved in motion perception is leisured, it caused sudden appearance or disappearance of people and objects, motion not being fluid but rather in the stopping motion
(blindness to motion)

Question 2

attentional capture

Answer 2

the ability of motion to attract attention. The fact that movement can attract attention plays an important role in animal survival. You have probably seen animals freeze in place when they sense danger, freezing in place eliminates the attention-attracting effects of movement

Question 3

real motion

Answer 3

actual motion of an object

Question 4

illusory motion

Answer 4

perception of motion when there actually is none

Question 5

apparent motion

Answer 5

the most famous, and well-studied, type of illusory motion.

This perception is called apparent motion because there is no actual (or real) motion between the stimuli. This is the basis for the motion we perceive in movies, on television, and in moving signs that are used for advertising and entertainment

Question 6

induced motion

Answer 6

occurs when motion of one object (usually a large one) causes a nearby stationary object (usually smaller) to appear to move. For example, the moon usually appears stationary in the sky. However, if clouds are moving (a) past the moon on a windy night, the moon may appear to be racing through the clouds. In this case, movement of the larger object (clouds covering a large area) makes the smaller, but actually stationary, moon appear to be moving

Question 7

waterfall illusion

Answer 7

if you look at a waterfall for 30 to 60 seconds (be sure it fills up only part of your field of view) and then look off to the side at part of the scene that is stationary, you will see everything you are looking at - rocks, trees, grass - appear to move up for a few seconds

Question 8

optic array

Answer 8

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

Question 9

local disturbance in the optic array

Answer 9

a local disturbance in the optic array occurs when one object moves relative to the environment, covering and uncovering the stationary backround

Question 10

global optic flow

Answer 10

As Maria moves everything around her moves. The fact that everything moves at once is called global optic flow; this signals that Maria is moving but that the environment is stationary

Question 11

aperture problem

Answer 11

the fact that viewing only a small portion of a larger stimulus can result in misleading information about the direction in which the stimulus is moving

Question 12

how visual system can solve the aperture problem?

Answer 12

The visual system apparently can solve this problem (1) by using information from neurons in the MT cortex that pool the responses of a number of directionally selective neurons, and (2) by using information from neurons in the striate cortex that respond to the movement of the ends of objects

Question 13

coherence

Answer 13

All of the dots are moving in random directions. Newsome used the term coherence to indicate the degree to which the dots move in the same direction.

Question 14

what happens as the dots’ coherence increases?

Answer 14

(1) the monkey judged the direction of motion more accurately, and (2) the MT neuron fired more rapidly

Question 15

MT leisures and coherence detection

Answer 15

a monkey with an intact MT cortex can begin detecting the direction dots are moving when coherence is as low as 1–2 percent. However, after the MT is lesioned, the coherence must be 10–20 percent before monkeys can begin detecting the direction of motion

Question 16

microstimulation

Answer 16

is achieved by lowering a small wire electrode into the cortex and passing a weak electrical charge through the tip of the electrode. This weak shock stimulates neurons that are near the electrode tip and causes them to fire, just as they would if they were being stimulated by neurotransmitters released from other neurons.

Question 17

motor signals (MS)

Answer 17

our eyes move because motor signals (MS) are being sent from the motor area of your brain to your eye muscles

Question 18

corollary discharge signal (CDS)

Answer 18

corollary discharge signal splits off from the motor signal. the corollary discharge signal, which occurs anytime a motor signal is sent to the eye muscles, indicates that a signal has been sent from the brain to move the eye.

Question 19

comparator

Answer 19

relays information back to the brain that the eye is moving

Question 20

image displacement signal

Answer 20

when an image moves across the retina this movement activates the retinal receptors and sends a signal out the optic nerve that we will call the image displacement signal (IDS) because it occurs when a stimulus is displaced across the retina

Question 21

when does perception of movement occur?

Answer 21

perception of movement occurs if the comparator receives either (1) a signal that the eye is moving (CDS) or (2) a signal that an image is being displaced across the retina (IDS)
- but when both the CDS and IDS reach the comparator simultaneously, no signal is sent to the brain, so no motion is perceived

Question 22

real-motion neuron

Answer 22

it responds only when the stimulus moves and doesn’t respond when the eye moves, even though the stimulus on the retina - a bar sweeping across the cell’s receptive field - is the same in both situations

Question 23

point-light walker stimuli

Answer 23

stimuli are created by placing small lights on people’s joints and then filming the patterns created by these lights when people worked and carried out other actions in the dark

Question 24

biological motion

Answer 24

motion of a person or other living organism
is perceived in STS (superior temporal sulcus)

Question 25

implied motion

Answer 25

situation where a still picture depicts a situation involving motion

Question 26

representational momentum

Answer 26

the idea that the motion depicted in a picture tends to continue in the observers’ mind