the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them
the minimum stimulation needed to detect a particular stimulus 50 percent of the time.
signal detection theory
a theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single absolute threshold and that detection depends partly on a person's experience, expectations, motivation, and alertness
the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response
the minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference.
the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)
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 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.
The dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth.
the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave's amplitude
a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening
the transparent structure behind the pupil that changes shape to help focus images on the 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
the process by which the eye's lens changes shape to focus near or far objects on the retina
retinal receptors that detect black, white and gray; necessary for peripheral and twilight vision, when cones don't respond
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.
the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there.
nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.
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 any color. (Myers Psychology 8e p. 212)
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 number of complete wavelengths that pass a point in a given time (for example, per second)
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.
a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses
the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs
in hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated
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
conduction hearing loss
hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea
hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves, also called nerve deafness.
a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.
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.
The principle that one sense may influence another, as when the smell of food influences its taste.
an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes
the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground).
the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance
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.
depth cues, such as interposition and linear perspective, available to either eye alone
an illusion of movement created when two or more adjacent lights blink on and off in quick succession
perceiving objects as unchanging (having consistent lightness, color, shape, and size) even as illumination and retinal images change
perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object
in vision, the ability to adjust to an artificially displaced or even inverted visual field
extrasensory perception (ESP)
the controversial claim that perception can occur apart from sensory input. Said to include telepathy, clairvoyance, and precognition
the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment
the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events
analysis that begins with the sensory receptors and works up to the brain's integration of sensory information
information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations