the minimum stimulation needed to detect a particular stimulus 50 percent of the time.

analysis that begins with the sensory receptors and works up to the brain's integration of sensory information.

failing to notice changes in the environment.

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

the minimum difference between two stimuli required for detection 50 percent of the time. Also called the just noticeable difference (jnd).

failing to see visible objects when our attention is directed elsewhere.

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.

the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

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.

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

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

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.

the sense of body movement and position, including the sense of balance.

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.