PSYC 101 Chapter 4

sensation

stimulation of sensory organs

perception

interpreting sensory input

light

electromagnetic radiation that travels as a wave

amplitude

height, affects brightness of light

wavelength

distance between peaks, affects color of light

purity

how varied the mixture of wavelengths are, affects saturation

cornea

window where light enters, protects eye

lens

behind cornea, focuses light falling on retina

pupil

opening in iris, regulates amount of light entering

retina

inner surface of eye, contains cones and rods, sends visual info to brain

optic disc

hole in retina where axons exit eye to form optic nerve, blind spot, no photoreceptors

cones and rods

receptor cells in retina that are sensitive to light

cones

daylight and color vision

fovea

spot in retina with only cones, most visual acuity

rods

night and peripheral vision

dark adaptation

process where eyes are more sensitive to light in dim lighting

light adaptation

process where are are less sensitive to light

receptive field

retinal area, when stimulated, a neuron will fire signals

optic chiasm

axons from each eye cross over to opposite half of brain

visual pathway

• light strikes cones and rods

• goes to bipolar cells

• goes to ganglion cells

• send impulses to optic nerve to brain

main visual pathway

• retina to thalamus to primary visual cortex

• ventral and dorsal streams (what and where)

second visual pathway

• midbrain to thalamus to occipital lobe

• visual and sensory input

feature detectors

neurons of visual cortex that respond to specific stimuli

subtractive color mixing

remove some wavelengths of light

additive color mixing

put more light in mixture

trichromatic theory

eye has three receptors sensitive to different light wavelengths

dichromats

have only two color receptors

afterimage

visual image after a stimulus is removed

opponent process theory

cells in the brain respond oppositely in pairs (red-green)

perceptual set

readiness to perceive a stimulus in one way, sets expectations

inattentional blindness

can’t see fully visible objects because attention is elsewhere

feature analysis

seeing small elements to make a whole perception

bottom up processing

gestalt psychology

whole can be greater than the sum of its parts

phi phenomenon

illusion of movement by showing visual stimuli rapidly

perceptual hypothesis

readiness to interpret stimuli in a specific way due to past experiences

retinal disparity

objects within 25 feet have slightly different locations between left and right eyes

monocular depth cues

cues about distance based on an image

perceptual constancy

ability to perceive objects as stable despite changing sensory input (size)

soundwaves

vibrations of molecules

frequency

affects pitch, measured by hertz

amplitude (sound)

affects loudness, measured by decibels

purity (sound)

affects timbre, measured by complexity of sounds

external ear

has pinna, a cone collecting sounds

has eardrum, a canal funneling sound waves

middle ear

3 ossicles channel the eardrum’s vibrations

ossicles

hammer, anvil, stirrup

inner ear

has cochlea, a fluid-filled tunnel with hearing receptors

basilar membrane

runs along cochlea, holds hair cells (auditory receptors)

place theory

pitch perception is the vibration of different places of basilar membrane

frequency theory

pitch perception is the rate of the entire basilar membrane vibrating

auditory localization

finding the source of a sound (timing and loudness)

taste pathway

thalamus to insular cortex of frontal lobe

sensory adaptation

decline in sensitivity after prolonged stimulation

smell pathway

olfactory axons synapse with olfactory bulb cells to olfactory cortex in temporal lobe

touch pathway

thalamus to sensory cortex in parietal lobe

fast pathway

localized pain

relays to cortex quickly

slow pathway

less localized pain, longer lasting

limbic system

gate control theory

pain passes through a gate in the spinal cord

gate can block pain signals