Semaine 4 - Wolfe et al, 2015, chap. 8 - Online activities 4ed Flashcards
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.
aperture problem
Qui suis-je ?
An opening that allows only a partial view of an object.
aperture
Qui suis-je ?
The illusory impression of smooth motion resulting from the rapid alternation of objects that appear in different locations in rapid succession.
apparent motion
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.
comparator
Qui suis-je ?
A type of voluntary eye movement in which the eyes move smoothly to follow a moving object.
smooth pursuit
Qui suis-je ?
A structure in the midbrain that is important in initiating and guiding eye movements.
superior colliculus
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.
tau (τ)
Qui suis-je ?
An object that is defined by differences in contrast, or texture, but not by luminance.
texture-defined object or contrast-defined object
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.
time to collision (TTC)
Qui suis-je ?
- 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.
- 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.
correspondence problem
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.
focus of expansion
Qui suis-je ?
The transfer of an effect (such as adaptation) from one eye to the other.
interocular transfer
Qui suis-je ?
An object that is delineated by differences in reflected light.
luminance-defined object
Qui suis-je ?
An area of the brain thought to be important in the perception of motion.
middle temporal area (MT)
Qui suis-je ?
The illusion of motion of a stationary object that occurs after prolonged exposure to a moving object.
motion aftereffect (MAE)
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.
optic array
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.
optic flow
Qui suis-je ?
A movement of the eye that is automatic and involuntary.
reflexive eye movement
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.
saccade
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.
saccadic suppression
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).
vergence
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.
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.
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).
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).
Strong physiological and behavioral evidence suggests that the ——- temporal area (MT) is involved in the perception of global motion.
Strong physiological and behavioral evidence suggests that the middle temporal area (MT) is involved in the perception of global motion.
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.”
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.”
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 ?
Non
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 ?
Non.
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 ?
Oui.
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
Oui.
Web Activity 8.4: Motion Aftereffects:
Réalisez un transfert interoculaire avec ce défilement de points. Qu’observez-vous ?
“You should experience a noticeable MAE even with the eye that was not viewing the moving dots.”
Web Activity 8.2: Types of Motion
Quel type de mouvement est ici illustré ?
Mouvement apparent
Web Activity 8.2: Types of Motion
Quel type de mouvement est ici illustré ?
Mouvement apparent (problème d’ouverture)
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 ?
“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.”
Web Activity 8.2: Types of Motion
Quel type de mouvement est ici illustré ?
Mouvement apparent (Correlated-Dot Motion)
Web Activity 8.2: Types of Motion
Où est l’optic flow dans ce film ?
À la barre blanche:
“The motion across the retina of stationary objects in the environment as the observer moves is called optic flow.”
Web Activity 8.2: Types of Motion
Où est le point d’expansion dans ce film ?
Au centre du film:
“The FOE is directly in the center of the movie”
