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sensation

• an organized whole that is perceived as more than the sum of its parts.
• 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.
• the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.
• the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount).

perception

• the principle that one sense may influence another, as when the smell of food influences taste
• the minimum difference between two stimuli required for detection 50% of the time; also referred to as just noticeable difference (JND)
• the process of organizing and interpreting sensory information; enabling us to recognize meaningful objects and events.
• the process by which the eye's lens changes shape to focus near or far objects on the retina.

bottom-up processing

• the nerve that carries neural impulses from the eye to the brain.
• the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount).
• the process by which the eye's lens changes shape to focus near or far objects on the retina.
• analysis that begins with the sense receptors and works up to the brain's integration of sensory information.

top-down processing

• the system for sensing the position and movement of individual body parts; enabled by feedback from proprioceptors (which provide info about the movement of muscles, tendons, joints); also called "proprioception"
• Activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response
• the central focal point in the retina, around which the eye's cones cluster.
• information processing guided by higher-level mental process, as when we construct perceptions drawing out our experience and expectation.

absolute threshold

• Gestalt grouping principle; we group similar figures together
• the minimum stimulation needed to detect a particular stimulus 50 percent of the time.
• Retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond.
• the principle that one sense may influence another, as when the smell of food influences taste

signal detection theory

• sound information that depends on frequency (or wavelength) of sound waves
• a theory predicting how and when we detect the presence of a faint stimuli ("signal") amid background stimulation ("noise"). Assumes that there is no single absolute threshold and that focuses more on the processing of briefly stored information. (e.g. what determines a "hit", "miss," "false alarm" or "correct rejection")
• mental predisposition to perceive one thing and not another (for example, due to suggestion or expectations based on prior learning)
• ability to selectively attend to one voice among many

difference threshold

• sense of smell
• the number of complete wavelengths that pass a point in a given time; determines perception of hue in light and of pitch in sound
• the minimum difference between two stimuli required for detection 50% of the time; also referred to as just noticeable difference (JND)
• the dimension of color that is determine by the wavelength of light; what we know as the color names blue, green, and so forth.

Weber's law

• the brain's perception of continuous movement in a rapid series of slightly varying images; this is how we perceive motion in film and animation
• the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount).
• Gestalt grouping principle; when objects uniform (in color or texture) are linked (no space exists between them) we perceive them as a single unit
• Gestalt grouping principle; we group nearby figures together

sensory adaptation

• credited with founding Gestalt Psychology; also conducted studies of insight learning in chimps
• the process by which the eye's lens changes shape to focus near or far objects on the retina.
• diminished sensitivity as a consequence of constant stimulation.
• the central focal point in the retina, around which the eye's cones cluster.

transduction

• Gestalt grouping principle; we fill in "gaps" to create a full, complete object
• conversion of one form of energy into another. In sensation, the transforming of stimulus energies into neural impulses.
• the third layer of retinal neurons whose axons leave the eyeball and form the optic nerve.
• the principle that one sense may influence another, as when the smell of food influences taste