Chapter 8 (M. Wolfe) Flashcards
What is the correspondence problem of motion?
The correspondence problem of motion is the problem faced by the motion detection system of knowing which feature in frame 2 corresponds to which feature from frame 1.
Describe the aperture problem.
The aperture problem is 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 is ambiguous.
What does interocular transfer tell us about the locus of motion aftereffects in the visual system?
Answer: Interocular transfer, which is the transfer of an effect from one eye to the other, tells us that the motion aftereffect must be reflecting the activities of neurons in a part of the visual system where information from the two eyes is combined—specifically, some area in primary visual cortex or later.
Why is tau important to navigating in the real world?
Tau is a measure of how quickly an image is expanding on the retina and can be used to determine time to collision without having to estimate absolute distances or rates. By calculating tau, the visual system helps us avoid collision, which is important for navigating in the world.
What is the focus of expansion?
When an observer is in motion, the focus of expansion is the point in the center of the horizon from which all points in the perspective image seem to emanate. The focus of expansion is one aspect of optic flow.
What is the role of the superior colliculus in the midbrain?
Answer: The superior colliculus is a structure that is important for initiating and guiding eye movements.
What is the role of vergence eye movements?
Vergence eye movements are helpful when one is focusing on objects stratified in depth. In this type of eye movement, the two eyes move in opposite directions: they either diverge outward, or converge inward.
Describe what happens in the disorder called akinetopsia.
Akinetopsia is a rare neuropsychological disorder in which the affected individual has no perception of motion. They experience a succession of static images but cannot perceive the motion connecting them.
comparator
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).
focus of expansion
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. One aspect of optic flow
interocular transfer
The transfer of an effect (such as adaptation) from one eye to the other.
optic array
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.
reflexive eye movement
A movement of the eye that is automatic and involuntary.
texture-defined object or contrast-defined object
An object that is defined by differences in contrast, or texture, but not by luminance.
