AP Psychology Sensation and Perception

sensation

stimulation of sense organs

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

prosopagnosia

facial blindness

blindsight

a condition in which a person can respond to a visual stimulus without consciously experiencing it

transduction

transforming stimulus energies into neural impulses our brains can interpret

absolute threshold

minimum stimulation needed to detect a particular stimulus fifty half the time

just noticeable difference

minimal change in a stimulus that can just barely be detected

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

light's wavelength

distance from one wave peak to the next, determines the hue our eyes experience

light's wavelength amplitude

the height of a wave peak; determines light's intensity; the amount of energy the wave contains

lens

changes shape to help focus images on the retina

accommodation

lens changes its curvature and thickness to focus the rays onto the retina

retina

layer of tissue at the back of the eye that contains photoreceptor cells

fovea

central point in the retina

nearsightedness

can see objects up close but not far away

farsightedness

can see objects far away but not up close

photoreceptors

rods and cones

rods

retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision

cones

retinal receptor cells that are concentrated near the center of the retina and that function in light conditions, detecting fine detail and give rise to color sensations

ganglion cells

specialized neurons that connect to the bipolar cells in the retina

visual nerve (optic nerve)

bundles axons of ganglion cells that carry neural impulses from the eye to the brain

blind spot

the point at which the optic nerve leaves the eye where there are no receptors

trichromatic theory

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

opponent-process theory

theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision

afterimages

images that occur when a visual sensation persists for a brief time even after the original stimulus is removed

monochromats

people who have total color blindness

dichromats

people who have partial color blindness

amplitude

height of a wave

pitch

highness or lowness of a sound

cochlea

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

vestibular sense

the sense of body movement, position, and balance

semicircular canals

three canals within the inner ear that contain specialized receptor cells that generate nerve impulses with the vestibular sense

conduction deafness

inability to hear resulting from damage to structures of the middle or inner ear

sensorineural deafness

deafness that results from damage to the auditory nerve

place theory

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

frequency theory

theory that links the pitch we hear with the frequency at which nerve impulses travel up the auditory nerve

volley theory

theory that links the pitch we hear with the frequency at which alternating nerve impulses travel up the auditory nerve

localizing sound

sound waves are detected differently by each ear depending on the direction they come from