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AP Psyc Chapter 5 Terms
Sensation The process by which our sensory receptors and our nervous system receive and represent stimulus energies from our environment.
Perception The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.
Bottom-up processing Analysis that begins with the sense receptors and works up to the brain's integration of sensory information.
Top-down processing Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.
Psychophysics The study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them.
Absolute threshold The minimum stimulation needed to detect a particular stimulus 50 percent of the time.
Subliminal Below one's absolute threshold for conscious awareness.
Difference threshold The minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference.
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).
Sensory adaptation Diminished sensitivity as a consequence of constant stimulation.
Wavelength The distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission.
Hue The dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth.
Intensity The amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave's amplitude.
Accommodation The process by which the eye's lens changes shape to focus near or far objects 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.
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.
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 several 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.
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 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.
Color constancy Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object.
Visual capture The tendency for vision to dominate the other senses, as when we perceive voices in films as coming from the screen we see rather than from the projector behind us.
Audition The sense of hearing.
Frequency The number of complete wavelengths that pass a point in a given time (for example, per second).
Pitch A tone's 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.
Inner ear The innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.
Cochlea A coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses.
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.
Sensory interaction The principle that one sense may influence another, as when the smell of food influences its taste.
Kinesthesis 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.
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 cues Depth cues, such as retinal disparity and convergence, that depend on the use of two eyes.
Monocular cues Distance cues, such as linear perspective and overlap, available to either eye alone.
Retinal disparity A binocular cue for perceiving depth: By comparing images from the two eyeballs, the brain computes distance--the greater the disparity (difference) between the two images, the closer the object.
Convergence A binocular cue for perceiving depth; the extent to which the eyes converge inward when looking at an object.
Perceptual constancy perceiving objects as unchanging (having consistent lightness, color, shape, and size) even as illumination and retinal images change.
Perceptual adaption In vision, the ability to adjust to an artificially displaced or even inverted visual field.
Perceptual set A mental predisposition to perceive one thing and not another.
Extrasensory perception (ESP) The controversial claim that perception can occur apart from sensory input. Said to include telepathy, clairvoyance, and precognition.
Parapsychology the study of paranormal phenomena, including ESP and psychokinesis.