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| The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment. |
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| The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events. |
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| Analysis that begins with the sensory receptors and works up to the brain's integration of sensory information |
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| Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations. |
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| The study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them. |
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| The minimum stimulation needed to detect a particular stimulus 50 percent of the time. |
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| 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 level of fatigue. |
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| Below one's absolute threshold for conscious awareness. |
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| The activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response. |
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| The minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference. (Also called "just noticeable difference" or jnd.) |
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| The principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount). |
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| Diminished sensitivity as a consequence of constant stimulation. |
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| Conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sound, and smells, into neural impulses our brains can interpret. |
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| 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. |
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| The dimension of colour that is determined by the wavelength of light; what we know as the colour names blue, green, and so forth. |
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| The amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave's amplitude. |
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| The adjustable opening in the center of the eye through which light enters. |
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| A ring of muscle tissue that forms the coloured portion of the eye around the pupil and controls the size of the pupil opening. |
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| The transparent structure behind the pupil that changes shape to help focus images on the retina. |
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| The process by which the eye's lens changes shape to focus near or far objects on the retina. |
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| 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. |
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| A condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of the retina. |
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| A condition in which far-away objects are seen more clearly than near objects because the image of near objects is focused behind the retina. |
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| Retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond. |
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| 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 colour sensations. |
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| The nerve that carries neural impulses from the eye to the brain. |
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| The point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there. |
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| The central focal point in the retina, around which the eye's cones cluster. |
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| Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement. |
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| 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. |
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| Young-Helmholtz Trichromatic Theory |
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| The theory that the retina contains three different colour receptors- one most sensitive to red, one to green, one to blue- which when stimulated in combination can produce the perception of any colour. |
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| Theory that opposing retinal processes (red-green, yellow-blue, white-black) enable colour vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green. |
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| Perceiving familiar objects as having consistent colour, even if changing illumination alters the wavelengths reflected by the object. |
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| The sense or act of hearing. |
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| The number of complete wavelengths that pass a point in a given time (for example, per second). |
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| A tone's experienced highness or lowness; depends on frequency. |
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| 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. |
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| A coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses. |
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| The innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs. |
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| In hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated. |
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| 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. |
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| Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea. |
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| Sensorineural Hearing Loss |
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| Hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness. |
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| A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea. |
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| 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. |
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| The principle that one sense may influence another, as when the smell of food influences its taste. |
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| The system for sensing the position and movement of individual body parts. |
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| The sense of body movement and position, including the sense of balance. |
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