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