Perception
1.Sensation: the process by which our sensory receptors and nervous
system receive and represent stimulus energies from our
environment.
2.Perception: the process of organizing and interpreting sensory
information; en- abling us to recognize meaningful objects and events.
3.Bottom-up processing: analysis that begins with the sense receptors
and works up to the brain's integration of sensory information.
4.Top-down processing: information processing guided by higher-level
mental process, as when we construct perceptions drawing out our
experience and expec- tation.
5.Absolute threshold: the minimum stimulation needed to detect a
particular stimulus 50 percent of the time.
6.Signal detection theory: a theory predicting how and when we detect
the pres- ence of a faint stimuli ("signal") amid background stimulation
("noise"). Assume 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")
7.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 (also called just
noticeable difference or JND.)
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, 8.Subliminal Sensation: detection of stimuli below absolute threshold
9.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).
10.Sensory Adaptation: diminished sensitivity as a consequence of
constant stim- ulation.
11.Transduction: conversion of one form of energy into another. In
sensation, the transforming of stimulus energies into neural impulses.
12.Wavelength: 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.
13.Hue: the dimension of color that is determine by the wavelength of
light; what we know as the color names blue, green, and so forth.
14.Pupil: the adjustable opening in the center of the eye through which
light enters.
15.Iris: a ring of muscle tissue that forms the color portions of the eye
around the pupil and controls the size of the pupil opening.
16.Lens: the transparent structure behind the pupil that changes
shape to help focus images on the retina.
17.Accommodation: the process by which the eye's lens changes shape
to focus near or far objects on the retina.
18.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.
19.Acuity: the sharpness of vision.
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