Lesson 8

Question 1

akinetopsia

Answer 1

“motion blindness,” where motion is either very difficult or
impossible to perceive.

Question 2

Induced motion

Answer 2

occurs when motion of one object (usually a large one) causes a nearby stationary object (usually smaller) to appear to move.

Question 3

Motion aftereffects

Answer 3

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

Question 4

optic array

Answer 4

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

Question 5

local disturbance in the optic array

Answer 5

portions of the optic array become covered as he walks by and then are uncovered as he moves on

Question 6

global optic flow

Answer 6

signals that the environment is stationary and that the observer is moving, either by moving her body or by scanning with her eyes

Question 7

Reichardt detector

Answer 7

Neurons A and B are stimulated when an object (the red dot) enters its receptive field. Activation is indicated by green, and by the numbered spike records. Panels (a) and (b) show activity within the detector as an object moves from left to right at two different points in time. The signals from neurons A and B meet at the output unit, and motion is perceived. Panels (c), (d), and (e) show activity within the same detector when an object moves from right to left at two points in time. In this case, the signals from A and B do not meet at the output unit, so no motion is perceived.

Question 8

Corollary discharge theory

Answer 8

Eye movement. The visual system takes into account both information about stimulation of the receptors and information about movement of the eyes.

Question 9

image displacement signal (IDS)

Answer 9

occurs when an image moves across receptors in the
retina, as when Jeremy walks across Maria’s field of view
while she stares straight ahead.

Question 10

motor signal (MS)

Answer 10

occurs when a signal is sent from the brain to the eye muscles. This signal occurs when Maria moves her eyes to follow
Jeremy as he walks across the room.

Question 11

corollary discharge signal (CDS)

Answer 11

copy of the motor signal that, instead of going to the eye muscles, is sent to a different place in the brain

Question 12

aperture problem.

Answer 12

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 13

solving the aperture problem

Answer 13

1. look at the end of a moving object to determine its direction of motion.
2. pool, or combine, responses
   from a number of neurons.

Question 14

shortest path constraint

Answer 14

apparent movement tends to occur along the shortest path between two stimuli.

Question 15

point-light walkers

Answer 15

small lights on people’s joints and then filming the patterns created by these lights when people walk and carry out other actions in the dark

Question 16

The… is more active when seeing biological motion compared to scrambled motion

Answer 16

the superior temporal sulcus (STS), FFA, PFC

Question 17

representational momentum

Answer 17

The idea that the motion depicted in a picture tends to continue in the observer’s mind