In order to continue enjoying our site, we ask that you confirm your identity as a human. Thank you very much for your cooperation. *Sensation - the process by which our sensory receptors and 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 sensory 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. *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 detection depends partly on a person's experience, expectations, motivation, and level of fatigue. 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. *Weber's Law - states that the difference threshold is directly proportional to the magnitude of the stimulus with which the comparison is being made. *Sensory Adaptation - diminished sensitivity as a consequence of constant stimulation. *Transduction - 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. Wavelength - the distance from the peak of one light or sound wave to the peak of the next. Hue - the dimension of color that is determined by the wavelength of light. 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. *Pupil - the 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 - the transparent structure behind the pupil that changes shape to help focus images on the retina. *Accomodation - the process by which the eye's lens changes shape to focus near or far objects on the retina. *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. 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, no receptor cells are located there. *Fovea - the central focal point in the retina, around which the eye's cones cluster. *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. Acuity - the sharpness of vision. Nearsightedness - a condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of the retina. Farsightedness - a condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind the retina. 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. *Young-Helmholtz 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 enable color vision. *Color Constancy - perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object. Audition - the sense of hearing. Frequency - the number of waves that pass a given point in a specific time, usually one 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 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. *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. *Conduction Hearing Loss - hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea. Nerve Deafness - hearing loss created by damage to the hair cells or the auditory nerve fibers in the inner ear. *Gate Control Theory - theory that spinal cord contains neurological gate that blocks pains signals or allows them to pass. Opened by activity of pain going up small nerve fibers & is closed by act of large fibers or by info coming from 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. *Sensorineural Hearing Loss - hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness.
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