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.
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 many 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.
gestalt
an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.
figure-ground
the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground).
grouping
the perceptual tendency to organize stimuli into coherent groups.
depth perception
the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance.
visual cliff
a laboratory device for testing depth perception in infants and young animals.
binocular cue
depth cues, such as retinal disparity, that depend on the use of two eyes.
retinal disparity
a binocular cue for perceiving depth: By comparingimages from the retinas in the two eyes, the brain computes distance— the greater the disparity (difference) between the two images, the closer the object.
monocular cue
depth cues, such as interposition and linear perspective, available to either eye alone.
phi phenomenon
an illusion of movement created when two or more adjacent lights blink on and off in quick succession.
perceptual constancy
perceiving objects as unchanging (having consistent shapes, size, brightness, and color) even as illumination and retinal images change.
color constancy
perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object.
perceptual adaptation
in vision, the ability to adjust to an artificially displaced or even inverted visual field.
audition
the sense or act of hearing.
frequency
the number of complete wavelengths that pass a point in a given time (for example, per second).
pitch
a tone's experienced highness or lowness; depends on frequency.
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; sound waves traveling through the cochlear fluid trigger nerve
inner ear
the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs
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 loss
hearing loss caused by damage to the echanical system that conducts sound waves to the cochlea.
cochlear implant
a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.
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.
gate-control theory
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.
olfaction
the sensation of smell that results from the detection of odorous substances aerosolized in the environment
kinesthesia
the system for sensing the position and movement of individual body parts.
vestibular sense
the sense of body movement and position, including the sense of balance.
sensory interaction
the principle that one sense may influence another, as when the smell of food influences its taste.
embodied cognition
in psychological science, the influence of bodily sensations, gestures, and other states on cognitive preferences and judgments.
gustation
the sense of taste