Chapter 5 Sensation 197-215

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

The analysis that beings with the senory 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.

Pychophysics

The study of relationships between physicla characteristics of stimuli (such as intensity) and our pyschological experience of them.

Absolute Threshold

The lowest level of stimulation that a person can detect

Signal Detection Theory

A theory predicting how and when we detect the presence of a faint simulus ("signal") amid background stimulation ("noise"), a theory predicting how and when we detect the presence of a faint simulus ("signal") amid background stimulation ("noise")

Subliminal

below the threshold of conscious perception; Ex. subliminal advertisement

Priming

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

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

Principle that the just noticeable diffference of a stimulus is a constant proportion despite variations.

Sensory Adaptation

Reduced responsiveness caused by prolonged 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. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission.

Hue

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

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

Accommodation

The process by which the eye's lens changes shape to focus near or far objects on the retina.

Retina

The light-sensitive membrane covering the back wall of the eyeball.

Acuity

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. (Myers Psychology 8e p. 206)

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.

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. The cones 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, creating a "blind" spot because no receptor cells are located there.

Fovea

The central focal point in the retina, around which the eye's cones cluster.

Parallel Processing

the processing of several aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision. Contrasts with the step-by-step (serial) processing of most computers and of conscious problem solving.

Young-Helmholtz Trichromatic Theory

Visual theory that all colors can be made by mixing the three basic colors: red, green, and blue; a.k.a the Young-Helmholtz theory.

Opponent Process Theory

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

Color Constantcy

Perceiving familiar objects as having color, even if changing illumination alters the wavelengths reflected by object.