APP Sensation and Perception Vocab 1

Modules 16 & 18

psychophysics

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

Gustav Fechner

historic psychologist; first student of psychophysics

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

analysis 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

absolute threshold

the minimum stimulation 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 detection depends partly on a person's experience, expectations, motivation, and level of fatigue

subliminal

below one's absolute threshold for conscious awareness

difference threshold (JND)

"just noticeable difference"-the minimum difference between two stimuli required for detection 50 percent of the time

Weber's law

principle that, to be percieved 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

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.

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

cornea

the clear tissue that covers the front of the eye

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 inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information

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

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

photoreceptors

rods and cones

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; detect fine detail and give rise to color sensations.

bipolar cells

eye neurons that receive information from the retinal cells and distribute information to the ganglion cells

ganglion cells

the specialized cells which lie behind the bipolar cells whose axons form the optic nerve which takes the information to the brain

optic nerve

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

optic chiasm

the crossing of the optic nerves from the two eyes at the base of the brain

lateral geniculate nucleus

the neural cluster on either side of the outside of the thalamus that receives visual input from the optic nerves

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

feature detectors

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

David Hubel and Torsten Wiesel

psychologists; sensation and perception--discovered feature detectors, groups of neurons in the visual cortex that respond to different types of visual stimuli

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

the theory that the retina contains three different color receptors--one for red, one for green, and one for blue--which, when stimulated in combination, can produce the perception of any color

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

synesthesia

a condition in which one type of sensory stimulus evokes a secondary and associated response. Example: hearing a sound and that invokes a color

foveal vision

sharp, central vision

sensory receptors

Specialized cells unique to each sense organ that respond to a particular form of sensory stimulation.

Wavelength

the distance from the peak of one light or sound wave to the peak of the next; determines hue in visual perception

cocktail party effect

ability to attend to only one voice among many