Module 17: Vision

Question 1

Transduction

Answer 1

conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brain can interpret.

Question 2

Wavelength

Answer 2

the distance from the peak of one light wave or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short gamma waves to the long pulses of radio transmission.

Question 3

Hue

Answer 3

the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth.

Question 4

Intensity

Answer 4

the amount of energy in a light wave or sound wave, which influences what we perceive as brightness or loudness. Intensity is determined by the wave’s amplitude (height).

Question 5

Iris

Answer 5

the colored portion of the eye that is a muscle that constrict or expands (dilates) the size of the pupil

Question 6

Pupil

Answer 6

the adjustable opening in the center of the eye through which light passes

Question 7

Retina

Answer 7

the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information.

Question 8

Accommodation

Answer 8

the process by which the eye’s lens changes shape to focus near or far objects on the retina.

Question 9

Rods

Answer 9

retinal receptors that detect black, white, and gray, and are sensitive to movement; necessary for peripheral and twilight vision, when cones don’t respond.

Question 10

Cones

Answer 10

retinal receptors that are concentrated near the center of the retina and that function in daylight or in well- lit conditions. Cones detect fine detail and give rise to color sensations.

Question 11

Optic Nerve

Answer 11

the nerve that carries neural impulses from the eye to the brain.

Question 12

Blind Spot

Answer 12

the point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there.

Question 13

Fovea

Answer 13

the central focal point in the retina, around which the eye’s cones cluster.

Question 14

Young-Helmholtz trichromatic (three-color) theory

Answer 14

the theory that the retina contains three different types of color receptors—one most sensitive to red, one to green, one to blue—which, when stimulated in combination, can produce the perception of any color.

Question 15

Opponent-process Theory

Answer 15

the theory that opposing retinal processes (red-green, blue-yellow, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green.

Question 16

Feature Detectors

Answer 16

nerve cells in the brain’s visual cortex that respond to specific features of the stimulus, such as shape, angle, or movement.

Question 17

Parallel Processing

Answer 17

processing many aspects of a stimulus or problem at once.

Question 18

Gestalt

Answer 18

an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.

Question 19

Figure-Ground

Answer 19

the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground).

Question 20

Grouping

Answer 20

the perceptual tendency to organize stimuli into coherent groups.

Question 21

Proximity

Answer 21

the tendency to group nearby things together

Question 22

Continuity

Answer 22

the tendency to perceive smooth, continuous patterns, rather than discontinuous ones

Question 23

Closure

Answer 23

the tendency to fill in gaps to create a composite, whole object.

Question 24

Depth Perception

Answer 24

the ability to see objects in three dimensions although the images that strike the retina are two- dimensional; allows us to judge distance.

Question 25

Visual Cliff

Answer 25

a laboratory device for testing depth perception in infants and young animals.

Question 26

Binocular Cue

Answer 26

a depth cue, such as retinal disparity, that depends on the use of two eyes.

Question 27

Retinal Disparity

Answer 27

a binocular cue for perceiving depth. By comparing retinal images from the two eyes, the brain computes distance—the greater the disparity (difference) between the two images, the closer the object.

Question 28

Monocular Cue

Answer 28

a depth cue, such as interposition or linear perspective, available to either eye alone.

Question 29

Phi Phenomenon

Answer 29

an illusion of movement created when two or more adjacent lights blink on and off in quick succession.

Question 30

Perceptual Constancy

Answer 30

perceiving objects as unchanging (having consistent color, brightness, shape, and size) even as illumination and retinal images change.

Question 31

Perceptual Adaptation

Answer 31

the ability to adjust to changed sensory input, including an artificially displaced or even inverted visual field.