Unit 3

sensation

receptors in sense organs activated, allow outside stimuli to become neural signals in brain

transduction

converting outside stimuli into neural activity

synesthesia

info interpreted as more than one sensation

JND

the smallest difference between two stimuli that is detectable 50 percent of the time

weber's law

easier to tell the difference between a weak stimulus and harder to detect change when stimulus is stronger

absolute threshold

consciously detect 50% of time stimulation is present

habituation

brains top attending to constant, unchanging info

sensory adaptation

sensory receptor cells become less responsive to unchanging stimulus

cornea

transparent dome, bends incoming light waves so image focuses on retina

iris

colored area containing muscles that control pupil

pupil

opening in center of iris, change size depending on light

lens

transparent disc, changes shape to focus objects

visual accomodation

change in thickness of lens as it focuses on objects far or close

retina

incoming light converted to nerve impulse, contains photoreceptor cells

rods

dark adaptation/ non color sensitivity

cones

light adaptation/ color & sharpness of vision

fovea

light rays most sharply focused

ganglion cells

neurons in the retina, final output neurons, make up a large portion of the optic nerve

optic nerve

transmit visual info from retina to occipital lobe

blind spot

area in retina where axons of retinal ganglion cells exit eye to form optic nerve

trichromatic theory

3 types of cones: red, green, blue

opponent-process theory

visual neurons stimulated by light of one color and inhibited by light of another

afterimage

visual sensation persists briefly after stimulus is removed

prosopagnosia

face blindness but can recognize objects

blindsight

those with damage to the visual cortex can detect visual stimuli presented to blind

convergence

rotation of eyes in their sockets to focus on a single object

retinal disparity

eyes see different things

outer ear

funnels sound waves into ear, entrance to auditory canal

tympanic membrane

eardrum

middle ear

hammer+anvil+stirrup= ossicles, vibrations of 3 bones amplify eardrum vibrations

inner ear

snail-shaped structure called cochlea, filled with fluid that surrounds basilar membrane

auditory nerve

bundles of axons from hair cells (on organ of corti) in inner ear

amplitude

volume

sound localization

identify changes in the position of sound sources based on acoustic info

conduction hearing loss

problem in outer or middle ear, sound vibrations can't be passed from eardrum to cochlea

nerve hearing impairment

problem in inner ear or auditory pathways & cortical areas

place theory

different pitches experienced by stimulation of hair cells in different locations on organ of corti

frequency theory

pitch is related to speed of vibrations in basilar membrane

volley theory

frequencies from 400-4000 Hz cause hair cells to fire in volley pattern

gustation

sensation of taste

olfaction

sense of smell

olfactory bulbs

areas of the brain located just above the sinus cavity and just below the frontal lobes that receive information from the olfactory receptor cells

olfactory fatigue

person's nose after exposure to certain odors is no longer able to detect the odor

somesthetic senses

consists of skin, kinesthetic, and vestibular senses

skin senses

process pain, pressure and temp

thermoreceptors

sensory neurons, detect temperature change

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.

kinesthetic

awareness of body movement

vestibular

sense of balance

semicircular canals

stimulate hairlike receptors when rotated

perception

sensation experienced interpreted & organized in some meaningful fashion

figure-ground

perceive figures as existing on a background

proximity

things close together appear more related than things spaced apart

similarity

perceive things that look similar to each other as part of same group

closure

complete figures that are incomplete

linear perspective

parallel lines appear to converge on each other

relative size

objects people expect to be a certain size appear small

interposition

object seems to be blocking another object (overlap)

texture gradient

textured surfaces appear to become smaller as distance from the viewer increases

motion parallax

close objects appear to move more quickly than objects that are farther away

perceptual set

perceive things a certain way because of previous experiences influence

top-down processing

use of preexisting knowledge to organize individual features into a whole

bottom-up processing

analysis of smaller features to build up to a complete perception