Visual Illusions

Question 1

visual perception

Answer 1

the activity by which an organism uses its eyes to obtain information about its environment and about itself in relation to its environment

Question 2

visual illusions

Answer 2

when visual perception makes mistakes that are large enough to be surprising

• help predict circumstances under which vision fails

Question 3

object recognition

Answer 3

what things are

Question 4

properties of things

Answer 4

size, shape, color, orientation

Question 5

space perception (spatial layout)

Answer 5

where things are; how things are arranged relative to each other

Question 6

absolute (metric) egocentric distance

Answer 6

where things are

Question 7

selective adaptation (response to motion)

Answer 7

• motion detectors (neurons) become sensitive/fatigued to a stimulus after prolonged exposure
• neurons adapt by decreasing rate of firing and firing less when stimulus is presented again
• adaptation causes us to be perceptually less sensitive to that stimulus

Question 8

spiral aftereffect

Answer 8

• neurons are being stimulated at different places on retina and fatigued
• each receptive field is only looking at one small part of retinal image (failure to see big picture leads to illusions)

Question 9

aperture illusion

Answer 9

• square is moving up but edge appears to be moving on a diagonal
• component of motion parallel to the edge cannot be seen; produces no vision motion
• neurons in V1 are not responding to the actual motion, only a component of motion (inaccurate, estimated motion)

Question 10

breathing square illusion

Answer 10

• appears to be contracting but is rigid

- shapes of openings bias the combination process

Question 11

motion binding

Answer 11

visual system’s ability to connect together the separated parts of a moving object
- varies when some parts are hidden by occluders

Question 12

geometrical illusions

Answer 12

simple line figures that produce large errors in perception

Question 13

linear perspective

Answer 13

2-D convergence: if lines in a 3D scene are parallel and slanted away from viewer, the lines will converge toward a vanishing point; creates depth perception in a flat picture

Question 14

motion parallax

Answer 14

when an observer moves relative to a 3D scene, the images of things that are closer move more than the images of things that are farther away

Question 15

concave vs convex

Answer 15

concave = curved away from you

convex = curved toward you