AP Psychology Unit 3: Sensation and Perception

sensation

occurs when special receptors (eyes, ears, nose, skin, and taste buds) are activated

transduction

process of converting outside stimuli, such as light, into neural activity

sensory receptors

specialized form of neurons

weber’s law

states that the size of the just noticeable difference (jnd) is a constant proportion

just noticeable difference (jnd)

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

absolute threshold

the smallest amount of energy needed for a person to consciously detect a stimulus 50 percent of the time it is present

difference threshold

the minimum amount of change in a stimulus that an individual can detect

subliminal stimuli

stimuli that are below the level of conscious awareness; strong enough to activate sensory receptors but not strong enough for people to be consciously aware of them

subliminal perception

subliminal stimuli acting upon the unconscious mind, influencing behavior

habituation

a decrease in response to a stimulus after repeated presentations

sensory adaptation

permits you to focus your attention on informative changes in your environment without being distracted by irrelevant data such as odors or background noises

signal detection theory

states that the detection of a stimulus depends on both the intensity of the stimulus and the physical or psychological state of the individual

perception

interpretation of sensations

brightness

determined by how high or low the wave is

color

determined by the length of the wave

saturation

refers to the purity of the color people receive

visible spectrum

portion of the whole spectrum that is visible to human eye

pupil

iris opening that changes size depending on the amount of light in the environment

iris

its muscles control the size of the pupil

aqueous humor

clear liquid that nourishes the eye

lens

changes shape to bring objects into focus

retina

nerve tissue lining the inside of the back of the eye that contains sensory receptors that convert light into nerve impulses and transmits the information to the brain through the optic nerves

fovea

central area of the retina; greatest density of photoreceptors

optic nerve

sends visual information to the brain

cornea

bends light waves so the image can be focuses on the retina (clear membrane that covers the eyes)

vitreous humor

jelly-like liquid that nourishes and gives shape to the eye

blind spot (optic disc)

area in the retina where visual information travels to the brain and thus no visual receptors are present

nearsightedness (myopia)

if too much curvature of the cornea and/or lens focuses on an image in front of them

farsightedness (hyperopia)

if too little curvature of the cornea and/or lens focuses behind the retina so distant objects are seen more clearly than nearby ones

visual accommodation

process where the lens change its shape from thick to thin, enabling it to focus on objects that are close or far away

ganglion cells

axons form optic nerve

bipolar cells

type of interneuron

rods/cones

photoreceptors; the business end of the retina

cones

visual sensory receptor found at the back of the retina; responsible for color vision and sharpness of vision

rods

visual sensory found at the back of the retina; responsible for noncolor sensitivity to low levels of light

dark adaptation

occurs as the eye recovers its ability to see when going from brightly lit state to a dark state

light adaptation

occurs as the eye recovers its ability to see when going from a dark state to a brightly lit state

feature detectors

individual neurons, or groups, in the brain which code for perceptually significant stimuli

parallel processing

simultaneous processing of stimulus elements

trichromatic theory

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

opponent process theory

theory of color vision that proposes four primary colors with cones arranged in pairs: red and green, blue and yellow

color blindness

caused by defective cones in the retina of the eye

monochrome color blindness

people either have no cones or have cones that are not working at all; everything looks like different shades of gray

dichromatic vision

having one cone that does not work properly; experiences the world with essentially combination of two cones or colors

anomalous trichromatism

having three types of cone cells that perceive light wave lengths, but one type perceives light slightly out of alignment

pinna

the outer ear that focuses sound waves for the middle and inner ears

auditory canal

short tunnel that runs from the pinna to the eardrum

auditory nerve

bundle of axons from the hair cells in the inner ear

hammer, anvil, and stirrup

three tiny bones in the middle ear; transmits vibrations caused by sound waves from the eardrum membrane to the liquid of the inner ear

cochlea

snail-like structure of the inner ear; filled with fluid called basilar membrane

cochlear implants

medical device surgically implanted to bypass damage in the inner ear and directly stimulate auditory nerve endings

basilar membrane

the resting place of the organ of corti

organ of corti

a structure of the inner ear essential to the processing of sound and the production of nerve signals that the brain can interpret

hair cells

the receptors for sound; sends neural messages to auditory nerve

conduction deafness

loss of hearing that results when the eardrums is punctured or any of the ossicles lose their ability to vibrate

nerve (sensorineural) deafness

results from damage to the cochlea, hair cells, or auditory nerves

gustation

the sensation of taste

taste buds

taste receptor cells; neurons found in the mouth that responsible for the sense of taste

papillae

bumps on the tongue

olfaction

the ability to smell odors

olfactory receptor cells

receptor sites that send signals to the brain when stimulated by molecules of substances that are in the air moving past them

olfactory bulbs

relay station for odor information from the nose to the brain

somesthetic senses

the body senses consisting of the skin senses, the kinesthetic sense, and vestibular senses

skin sense

having to do with touch, pressure, temperature, and pain

kinesthetic senses

sense of the location of body parts in relation to the ground and each other; special receptors located in the muscles, tendons, and joints

vestibular sense

the sensation of movement, balance, and body position; processed by vestibular organs

Pacinian corpuscles

beneath the skin and responds to changes in pressure

free nerve endings

beneath the uppermost layer of the skin that respond to changes in temperature, pressure, and pain

visceral pain

pain in the organs

somatic pain

pain sensations in the skin, muscles, tendons, and joints

gate control theory

suggests that pain signals must pass through a '“gate” located in the spinal cord

otolith organs

responsible for detecting linear head acceleration and tilt

semicircular canals

help control balance and senses head position

sensory conflict theory

proposes motion sickness is caused by a conflict between the visual, vestibular, and somatosensory system

size constancy

the tendency to interpret an object as always being the same size, regardless of its distance from the viewer

brightness constancy

the tendency to perceive the apparent brightness of an object as the same even when the light conditions change

figure ground relationships

the tendency to perceive objects or figures as existing on a background

proximity

the tendency to perceive objects that are close to one another as a part of the same grouping

similarity

the tendency to perceive things that look similar as being part of the same group

closure

the tendency to complete figures that are incomplete

continuity

the tendency to perceive things as simply as possible with a continuous pattern rather than with complex, broken up pattern

contiguity

the tendency to perceive two things that happen to be close together in time as related

linear perspective

the tendency for parallel lines to appear to converge on each other

relative size

perception that occurs when objects that a person expects to be of a certain size appear to be small and are therefore assumed to be much farther away

overlap

if one object seems to be blocking another object, people assume that the blocked object is behind the first one, and therefore farther away

aerial (atmospheric) perceptive

the farther away an object is, the hazier the object will appear to be due to particles in the air

texture gradient

the progressive decline in the resolution of texture as the viewer moves away from it

motion parallax

discrepancy in motion of near and far objects

accommodation

part of the adaptation process that involves altering existing ideas as a result of new information/experiences

convergence

refers to the rotation of the two eyes in their socket to focus on a single object

binocular disparity

because the eyes are a few inches apart, they don’t see exactly the same image

illusion

a perception that does not correspond to reality

muller lyer illusion

illusion of line length that causes lines of equal length to appear different

reversible figure

visual illusions in which the figure and ground can be reversed

perceptual set/expectations

tendency to perceive things a certain way because of previous experiences or expectations influencing them

top down processing

using preexisting knowledge to organize individual features as a unified whole

bottom up processing

when the brain processes sensory information and uses clues to understand stimuli

pitch

refers to how high or low a sound is

timbre

quality of sound that distinguishes it from other sounds

place theory

the pitch a person hears depends on where the hair cells that are stimulated are located on the organ of corti