AP Psychology Sensation and Perception

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.

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

cocktail party phenomenon

a phenomenon in which people tune in one message even while they filter out others nearby

accommodation

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

Psychophysics

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

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

absolute threshold

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

difference threshold

the minimum difference between two stimuli required for detection 50 percent of the time

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)

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.

feature detectors

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

optic nerve

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

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. Detects fine detail

Fovea

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

blind spot

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

trichromatic theory

theory of color vision that proposes three types of cones: red, blue, and green

color blindness

a variety of disorders marked by inability to distinguish some or all colors

Afterimage

A visual image that persists after a stimulus is removed.

frequency

the number of wavelengths that pass by a point each second. Length of wavelengths that determine pitch and red/blue colors.

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

Amplitude

Height of a wave that determines loudness/softness of a sound

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

Basalar membrane

tissue within the cochlea containing hair cells which serve as sensory receptors for the auditory system

place theory

in hearing, the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated

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

conduction deafness

An inability to hear resulting from damage to structures of the middle or inner ear that conduct sound waves to the cochlea.

nerve deafness

Hearing loss created by damage to the hair cells or the auditory nerve fibers in the inner ear.

gate-control theory

the theory that the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain. The "gate" is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain.

vestibular sense

the sense of body movement and position, including the sense of balance

kinesthetic sense

sense of the location of body parts in relation to the ground and each other

parallel processing

the ability of the brain to simultaneously process incoming stimuli of differing quality

perceptual constancy

perceiving objects as unchanging (having consistent lightness, color, shape, and size) even as illumination and retinal images change

phi phenomenon

to perceive a series of blinking lights down a line as one light

Rule of Proximity

things near one another belong together

rule of similarity

things that are physically similar are perceived as belonging together and forming a unit

rule of closure

we tend to fill in missing elements of a visual scene

rule of continuity

we perceive smooth, continuous patterns rather than discontinuous ones

perceptual adaptation

the ability of the body to adapt to an environment by filtering out distractions