the theory that the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain. The "gate" is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain.

five tastes:

sweet, sour, salty, bitter, umami

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.

sensory adaptation:

diminished sensitivity as a consequence of constant stimulation

sensorineural hearing loss:

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

conduction hearing impairment:

sound vibrations cannot be passed from the eardrum to the cochlea

opponent process theory of color vision:

the theory that receptor cells for color are linked in pairs, working in opposition to each other

monocular depth cues:

aspects of a scene that yield information about depth when viewed with only one eye

Weber's Law:

the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)

Gestalt Psychology:

a psychological approach that emphasizes that we often perceive the whole rather than the sum of the parts

Transduction:

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 brains can interpret.

Sensory Adaptation:

diminished sensitivity as a consequence of constant stimulation

Botttom-up processing:

perception that consists of recognizing and processing information about the individual components of the stimuli (can guess what the object is by seeing only one part of it)

top-down processing (perception):

information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations

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.

feature Detectors:

nerve cells in the brain that respond to specific features of the stimulus, such as color, form, motion, depth

Perceptual Set:

a mental predisposition to perceive one thing and not another

Monocular cues:

depth cues, such as interposition and linear perspective, available to either eye alone

binocular cues:

depth cues, such as retinal disparity and convergence, that depend on the use of two eyes

Stroop Effect:

Explains the decreased speed of naming the color of ink used to print words when the color of ink and the word itself are of different colors.

Note