Semaine 4 - Wolfe et al, 2015, chap. 8 - Online activities 4ed

Question 1

Que suis-je ?

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.

Answer 1

aperture problem

Question 2

Qui suis-je ?

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

Answer 2

aperture

Question 3

Qui suis-je ?

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

Answer 3

apparent motion

Question 4

Qui suis-je ?

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

Answer 4

comparator

Question 5

Qui suis-je ?

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

Answer 5

smooth pursuit

Question 6

Qui suis-je ?

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

Answer 6

superior colliculus

Question 7

Qui suis-je ?

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

Answer 7

tau (τ)

Question 8

Qui suis-je ?

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

Answer 8

texture-defined object or contrast-defined object

Question 9

Qui suis-je ?

The time required for a moving object (such as a cricket ball) to hit a stationary object (such as a batsman’s head). TTC = distance/rate.

Answer 9

time to collision (TTC)

Question 10

Qui suis-je ?

1. In binocular vision, the problem of figuring out which bit of the image in the left eye should be matched with which bit in the right eye. The problem is particularly vexing when the images consist of thousands of similar features, like dots in random dot stereograms.
2. In 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.

Answer 10

correspondence problem

Question 11

Qui suis-je ?

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

Answer 11

focus of expansion

Question 12

Qui suis-je ?

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

Answer 12

interocular transfer

Question 13

Qui suis-je ?

An object that is delineated by differences in reflected light.

Answer 13

luminance-defined object

Question 14

Qui suis-je ?

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

Answer 14

middle temporal area (MT)

Question 15

Qui suis-je ?

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

Answer 15

motion aftereffect (MAE)

Question 16

Qui suis-je ?

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

Answer 16

optic array

Question 17

Qui suis-je ?

The pattern of apparent motion of objects in a visual scene produced by the relative motion between the observer and the scene.

Answer 17

optic flow

Question 18

Qui suis-je ?

A movement of the eye that is automatic and involuntary.

Answer 18

reflexive eye movement

Question 19

Qui suis-je ?

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

Answer 19

saccade

Question 20

Qui suis-je ?

The reduction of visual sensitivity that occurs when we make saccadic eye movements. Saccadic suppression eliminates the smear from retinal image motion during an eye movement.

Answer 20

saccadic suppression

Question 21

Qui suis-je ?

A type of eye movement in which the two eyes move in opposite directions; for example, both eyes turn toward the nose (convergence) or away from the nose (divergence).

Answer 21

vergence

Question 22

Like color or orientation, motion is a —– perceptual dimension that is coded at various levels in the brain. Motion information is used to determine where objects are going and when they’re likely to get there, and to help us move through our environment without being hit in the head by flying objects.

Answer 22

Like color or orientation, motion is a primary perceptual dimension that is coded at various levels in the brain. Motion information is used to determine where objects are going and when they’re likely to get there, and to help us move through our environment without being hit in the head by flying objects.

Question 23

V1 neurons view the world through a small window, leading to the well-known ——– problem (that is, a V1 neuron is unable to tell which elements correspond with one another when an object moves through its receptive field).

Answer 23

V1 neurons view the world through a small window, leading to the well-known aperture problem (that is, a V1 neuron is unable to tell which elements correspond with one another when an object moves through its receptive field).

Question 24

Strong physiological and behavioral evidence suggests that the ——- temporal area (MT) is involved in the perception of global motion.

Answer 24

Strong physiological and behavioral evidence suggests that the middle temporal area (MT) is involved in the perception of global motion.

Question 25

The brain has to figure out which retinal motion arises in the world, and which arises because of eye movements. Moreover, the brain must ——- the motion signals generated by our eye movements, or the world will be pretty “smeared.”

Answer 25

The brain has to figure out which retinal motion arises in the world, and which arises because of eye movements. Moreover, the brain must suppress the motion signals generated by our eye movements, or the world will be pretty “smeared.”

Question 26

Web Activity 8.5: Eye Movements

S’il n’y a ni mouvement rétinien, ni mouvement oculaire, est-ce qu’il y a mouvement de l’objet ?

Answer 26

Non

Question 27

Web Activity 8.5: Eye Movements

S’il y a mouvement rétinien et mouvement oculaire, est-ce qu’il y a mouvement de l’objet ?

Answer 27

Non.

Question 28

Web Activity 8.5: Eye Movements

S’il y a mouvement rétinien, mais pas de mouvement oculaire, est-ce qu’il y a mouvement de l’objet ?

Answer 28

Oui.

Question 29

Web Activity 8.5: Eye Movements

S’il n’y a pas de mouvement rétinien, mais des mouvements oculaires, est-ce qu’il y a mouvement de l’objet

Answer 29

Oui.

Question 30

Web Activity 8.4: Motion Aftereffects:

Réalisez un transfert interoculaire avec ce défilement de points. Qu’observez-vous ?

Answer 30

“You should experience a noticeable MAE even with the eye that was not viewing the moving dots.”

Question 31

Web Activity 8.2: Types of Motion

Quel type de mouvement est ici illustré ?

Answer 31

Mouvement apparent

Question 32

Web Activity 8.2: Types of Motion

Quel type de mouvement est ici illustré ?

Answer 32

Mouvement apparent (problème d’ouverture)

Question 33

Web Activity 8.2: Types of Motion

Problème d’ouverture: Pourquoi dans le film 5, on ne peut pas saisir dans quel sens vont les pattern hachurés (striped patterns), celui que le film 6 dévoile ?

Answer 33

“When the three rectangles are visible, their edges provide unambiguous motion cues that help your visual system interpret the true motion of the stripes within the circular apertures. Without these global motion cues, your visual system finds the simplest explanation for the local motion of the stripes within the circular apertures–that they are all moving up and to the left. This is yet another example of how global motion cues help your visual system to resolve locally ambiguous motion.”

Question 34

Web Activity 8.2: Types of Motion

Quel type de mouvement est ici illustré ?

Answer 34

Mouvement apparent (Correlated-Dot Motion)

Question 35

Web Activity 8.2: Types of Motion

Où est l’optic flow dans ce film ?

Answer 35

À la barre blanche:

“The motion across the retina of stationary objects in the environment as the observer moves is called optic flow.”

Question 36

Web Activity 8.2: Types of Motion

Où est le point d’expansion dans ce film ?

Answer 36

Au centre du film:

“The FOE is directly in the center of the movie”