the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

analysis that begins with the sensory receptors and works up to the brain's integration of sensory information.

information processing guided by higher-level mental processes, as when we construct perceptons drawing on our experience and expectations

the focusing of conscious awareness on a particular stimulus

failing to see visible objects when our attention is directed elsewhere.

failing to notice changes in the environment (magicians exploit this)

the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them.

the minimum stimulation needed to detect a particular stimulus 50% of the time.

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 that depends partly on a person's experience, expectations, motivation, and alertness.

below one's absolute threshold for conscious awareness

the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response

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

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

diminished sensitivity as a consequence of constant stimulation

conversion of one's 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.

the distance from the peak of one light or sound wave to  the peak of the next.  Electromagnetic wavelengths vary from the sort blips of cosmic rays to the long pulses of radio transmission.

the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth

the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave's amplitude

the adjustable opening in the center of the eye through which light enters

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

the transparent structure behind the pupil that changes shape to help focus images on the 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

retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond

retinal receptor cellls that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. They detect fine detail and give rise to color sensations.

the nerve that carries neural impulses from the eye to the brain

the point at which the optic nerve leaves the eye, creating a blind spot because no receptor cells are located there.

the central focal point in the retina, around when the eye's cones cluster

nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement

the processing of many aspects of a probelm simultaneously; the brains natural mode of information processing for many functions, including vision.  Contrasts with the step-by-step (serial) processing of most ocmputers and of conscious problem solving

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.

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision.  For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green.