psych of perception chapter 8 Flashcards
motion agnosia
akinetopsia
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)
attentional capture
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
real motion
actual motion of an object
illusory motion
perception of motion when there actually is none
apparent motion
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
induced motion
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
waterfall illusion
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
optic array
the structure created by the surfaces, textures, and contours of the environment
local disturbance in the optic array
a local disturbance in the optic array occurs when one object moves relative to the environment, covering and uncovering the stationary backround
global optic flow
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
aperture problem
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
how visual system can solve the aperture problem?
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
coherence
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.
what happens as the dots’ coherence increases?
(1) the monkey judged the direction of motion more accurately, and (2) the MT neuron fired more rapidly
MT leisures and coherence detection
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