AP Psychology Module 18

wavelength

The distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission.

hue

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

intensity

The amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave's amplitude.

pupil

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

iris

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

lens

the transparent structure behind the pupil that changes shape to help focus images on the retina

retina

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

accomidation

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

rods

retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond.

cones

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

optic nerve

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

blind spot

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

fovea

The central focal point in the retina, around which the eye's cones cluster

feature detectors

Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement

parallel processing

the processing of several aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision. Contrasts with the step-by-step (serial) processing of most computers and of conscious problem solving.

Young-Helmholtz trichromatic (three-color) theory

the theory that the retina contains three different 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.

opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, 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

grouping

the perceptual tendency to organize stimuli into coherent groups.