AP Psych Unit 1B Vocab

Module 1.6a - Sensation: Basic Concepts

sensation

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

sensory receptors

sensory nerve endings 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 begins 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 smells, into neural impulses the brain can interpret.

psychophysics

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

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 presence of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single absolute threshold and that detection depends partly on a person’s experience, expectations, motivation, and alertness.

subliminal

below one’s absolute threshold 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 (or jnd).

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.

Module 1.6b - Sensation: Vision

wavelength

the distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short gamma waves 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 wave or sound wave, which influences what we perceive as brightness or loudness. Intensity is determined by the wave’s amplitude (height) and can influence brightness.

amplitude

a wave’s height

cornea

the eye’s clear, protective outer layer, covering the pupil and iris.=; bends light to help provide focus

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; very distinct, iris-scanning technology can conform identity

lens

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

retina

the light-sensitive back inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information.

accommodation

(1) in sensation and perception, the process by which the eye’s lens changes shape to focus images of near or far objects on the retina. (2) in developmental psychology, adapting our current schemas (understandings) to incorporate new information.

myopia

nearsightedness; can be remedied with glasses, contact lenses, or surgery

rods

retinal receptors that detect black, white, and gray, and are sensitive to movement; necessary for peripheral and twilight vision, when cones don’t respond.

cones

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

optic nerve

the nerve that carries neural impulses from the eye to the brain; formed by ganglion cells

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.

Young–Helmholtz trichromatic (three-color) theory

the theory that the retina contains three different types of 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.

opponent-process theory

the theory that opposing retinal processes (red-green, blue-yellow, 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.

feature detectors

nerve cells in the brain’s visual cortex that respond to specific features of the stimulus, such as shape, angle, or movement.

parallel processing

processing multiple aspects of a stimulus or problem simultaneously.

Module 1.6c - Sensation: Hearing

audition

the sense of act of hearing.

frequency

the number of complete wavelengths that pass a point in a given time (for example, per second). measured in hertz

pitch

a tone’s experienced highness or lowness; depends on frequency.

decibles

the measurement of sound intensity. zero decibels is the absolute threshold for heaving, measured on a logarithmic scale (every 10 decibels corresponds to a tenfold increase in intensity)

sensorineural hearing loss

the most common form of hearing loss, caused by damage to the cochlea’s receptor cells or to the auditory nerve; also called nerve deafness.

conduction hearing loss

a less common form of hearing loss, caused by damage to the mechanical system that conducts sound waves to the cochlea.

cochlear implant

a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.

place theory

in hearing, the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated. (Also called place coding.)

frequency theory

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. (Also called temporal coding.)