AP Psychology Eye & Ear Review

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.

Accommodation

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.

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.

Audition

The sense or act of hearing.

Middle Ear

The chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window.

Cochlea

a Coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulse.

Inner ear

The innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.

Place Theory

In hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated.

Frequency Theory

In Hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch.

Conduction Hearing Loss

Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea.

Sensorineural Hearing Loss

Hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness.

Cochlear Implant

A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.