AP Psych Unit 3: Mods 16-19

sensation

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

perception

process of organizing and interpreting sensory information, to recognize meaningful objects and events

bottom-up processing

analysis that begins with sensory receptors and works up to brain’s integration of sensory information (new info!)

top-down processing

information processing where we construct perceptions drawing on experience and expectations (things we alr know)

selective attention

conscious awareness of particular stimulus

inattentional blindness

failing to see visible objects when our attention is directed elsewhere

change blindness

failing to notice changes in the environment

transduction

conversion of one form of energy into another - in sensation, transforming of stimulus energies like sights, sounds, and smells, into neural impulses brain can interpret

psychophysics

study of relationships between physical characteristics of stimuli, like their intensity, and our psychological experience of them

absolute threshold

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

signal detection theory

theory predicting how and when we detect the presence of 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

priming

unconscious activation of certain associations, thus predisposing one’s perception, memory, or response

difference threshold

minimum difference between two stimuli required for detection 50% of the time - “just noticeable difference” (jnd)

weber’s law

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

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

perceptual set

mental predisposition to perceive one thing and not another

wavelength

distance from peak of one light or sound wave to peak of the next - electromagnetic wavelengths vary from short blips of cosmic rays to long pulses of radio transmission

hue

dimension of color that is determined by wavelength of light; what we know as color names like blue, green, red

intensity

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

pupil

adjustable opening in center of the eye through which light enters

iris

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

lens

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

retina

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

accomodation

process by which the eye’s lens changes shape to focus near or far objects on 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 concentrated near the center of the retina that function in daylight or in well-lit conditions - cones detect fine detail and give rise to color sensations

optic nerve

nerve that carries neural impulses from eye to brain

blind spot

point where optic nerve leaves eye, creating a “blind” spot because no receptor cells are located there

fovea

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

feature detectors

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

parallel processing

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

Young-Helmholtz trichromatic (three-color) theory

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

opponent-process theory

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

gestalt

an organized whole - Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes

figure-ground

organization of the visual field into objects (figures) that stand out from their surroundings (ground)

grouping

perceptual tendency to organize stimuli into coherent groups (proximity, continuity, closure)

depth perception

ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance

visual cliff

a laboratory device for testing depth perception in infants and young animals

binocular cues

depth cues, such as retinal disparity, that depend on the use of two eyes

retinal disparity

a binocular cue for perceiving depth: by comparing images from the retinas in the two eyes, the brain computes distance— the greater the disparity (difference) between the two images, the closer the object

monocular cues

depth cues, such as interposition and linear perspective, available to either eye alone

phi phenomenon

an illusion of movement created when two or more adjacent lights blink on and off in quick succession

perceptual constancy

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

color constancy

perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object (checkerboard colors)

perceptual adaptation

in vision - the ability to adjust to an artificially displaced or inverted visual field