- absolute threshold: minimum stimulus needed to detect a particular stimulus 50 percent of the time
- accommodation: process by which the eye's lens change shape to focus near or far objects on the retina
- acuity: sharpness of vision
- audition: sense or act of hearing
- blind spot: point at which the optic nerve leaves the eye, creating a "blind" spot
- bottom-up processing: analysis that begins with the sensory receptors and works up the brain's integration of sensory information
- cochlear implant: device for converting sounds into electrical signals and stimulating the auditory nerve
- color constancy: perceiving familiar objects as having consisten color, even if changing illumination alters the wavelengths reflected by the object
- conduction hearing loss: hearing loss caused by the damage to the mechanical system that conducts sound waves to the cochlea
- cones: retinal receptors that are concentrated near the center of the retina and detect fine detail and give rise to color sensations
- difference threshold: minimum difference between two stimuli required for detection 50 percent of the time
- farsightedness: condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind the retina
- fovea: central focal point in the retina, around which the eye's cones cluster
- frequency: number of complete wavelengths that pass a point in a given time
- frequency theory: in hearing, the theory that the rate of impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch
- gate-control theory: theory that the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain
- hue: dimension of color that is determined by the wavelength of light; blue, green, etc.
- inner ear: innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs
- intensity: amount of energy in a light or sound wave, which we perceive as brightness or loudness
- 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
- kinesthesis: system for sensing the position and movement of individual body parts
- lens: transparent structure behind the pupil that changes shape to help focus images on the retina
- middle ear: 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
- nearsightedness: condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of the retina
- opponent-process theory: theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision
- optic nerve: nerve that carries neural impulses from the eye to the brain
- parallel processing: processing of several aspects of a problem simultaneously; contrasts with the step-by-step processing of most problem solving
- perception: process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events
- pitch: tone's experienced hightness or lowness; depends on frequency
- place theory: in hearing, theory that links the pitch we hear with the place where the cochlea's membrane is stimulated
- priming: activation, often unconsciously, of certain association, thus predisposing one's perception, memory, or response
- pupil: adjustable opening in the center of the eye through which light enters
- retina: light-sensitive inner surface of the eye, containing the receptor rods and cones
- rods: retinal receptors that detect black, white, and gray
- sensation: process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment
- sensorineural hearing loss: hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves
- sensory adaptation: diminished sensitivity as a consequence of constant stimulation
- sensory interaction: principle that one sense may influence another, as when the smell of food influences its taste
- signal detection theory: predicting how and when we detect the presence of a faint stimulus amid background stimulation
- subliminal: below one's absolute threshold for conscious awareness
- top-down processing: information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations
- transduction: conversion of one form of energy into another.
- vestibular sense: sense of body movement and position, including the sense of balance
- wavelength: distance from the peak of one light or sound wave to the peak of the next
- Weber's law: principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage
- Young-Helmholtz trichromatic (three color) theory: theory that the retina contains three different color receptors- red, green, and blue