Sensations and Perceptions

sensation

the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment

sensory receptors

sensory nerve ending that respond to stimuli

perception

the process by which our brain organizes and interprets sensory information, enabling us to recognize objects and events as meaningful

bottom-up processing

information processing that beings 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

transduction

conversion of one form of energy into another. In sensation, the transforming of physical energy, such as sights, sounds, and smell, into neural impulses our brain can interpret

absolute threshold

the minimum stimulus energy needed to detect a particular stimulus 50 percent of the time.

Signal detection theory

a theory predicting how and when we detect the presense of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single threshold and that dectection depends partly on a person's experience, expectations, motivation, and alertness

subliminal

below one's absolute hold for conscious awareness

difference threshold

the minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference.

Weber's Law

the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)

Sensory adaptation

diminished sensitivity as a consequence of constant stimulation

perceptual set

a mental predisposition to perceive one thing and not another