Sensation and Perception

Weber's Law

Principle that the jnd for any given sense is a constant fraction or proportion of the stimulation being judged. Does NOT work well for very large or very small stimuli

Tympanic membrane

The eardrum. A structure that separates the outer ear from the middle ear and vibrates in response to sound waves.

C fibers

Unmyelinated fibers that detect aching pain, warm reception and itch reception

pupil

adjustable opening in center of eye through which light enters.

intensity

amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by wave's amplitude.

top-down processing

analysis guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.

bottom-up processing

analysis that begins with sensory receptors and works up to brain's integration of sensory info using feature detector cells in the brain via parallel processing

inner ear

area of ear, containing cochlea, semicircular canals, and vestibular sacs

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.

cornea

curved protective layer through which light rays enters the eye. Light rays are bent here as well as in lens.

cornea

curved protective layer through which light rays enters the eye. Light rays are bent here as well as in the lens.

afterimage

firing of rods or cones not used after viewing an object for a time that causes an image to appear in opposite colors

olfactory bulb

first brain structure to pick up smell info from nose which sends info on to limbic system (no thalamus)

transduction for audition

hair cells on the basilar membrane of the cochlea

sensorineural hearing loss

hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness.

conduction hearing loss

hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea.

place theory

in hearing, theory that links pitch we hear with location where cochlea's membrane is stimulated.

frequency theory

in hearing, theory that rate of nerve impulses traveling up auditory nerve matches rate of the sound wave resulting in pitch

retina

light-sensitive inner surface of eye, containing receptor rods and cones plus layers of neurons that begin processing of visual info.

analgesic

medicine used to relieve pain

difference threshold

minimum difference between two stimuli required for detection 50 percent of the time.

absolute threshold

minimum stimulation needed to detect a particular stimulus 50 percent of the time.

feature detectors

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

optic nerve

nerve that carries impulses from the eye to brain.

substance p

neurotransmitter involved in neural transmission of pain

frequency

number of complete wavelengths that pass a point in a given time (for example, per second).

transduction for kinesthesis

occurs in the muscles, tendons, and joints

cones

retinal receptor cells concentrated near center of retina that function in daylight or in well-lit conditions. Detect fine detail and give rise to color sensations.

rods

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

iris

ring of muscle tissue that forms colored portion of eye around pupil and controls size of pupil opening.

transduction for vision

rods and cones of retina

vestibular sense

sense of body movement and position, including the sense of balance. This also lets you know if your body is in a horizontal or vertical position.

gustation

sense of taste

audition

sense or act of hearing.

synethesia

sensory experiences may overlap so a patient may "hear" a color or "taste" a sound

acuity

sharpness of vision.

endorphins

"morphine within"--natural, opiate like neurotransmitters linked to pain control and to pleasure.

thalamus

A structure in the forebrain through which all sensory information (except smell) must pass to get to the cerebral cortex.

somatosensory cortex

Area at front of parietal lobe, which receives sensory info about touch, pressure, pain, temperature, and body position (kinesthesia)

pheromones

Chemicals secreted by animal species that influence the behavior of other animals of the same species in terms of mating and territory marking, etc.

Hubel and Wisel

Identified feature detectors - specialized visual cells in the cortex by studying cats

visual cliff

Laboratory device for testing depth perception in infants and young animals

Oval window

Membrane that covers opening between middle ear and inner ear - the membrane at the opening of the cochlea

phantom limb

Perceived sensation, following amputation of a limb, that limb still exists and may have pain

auditory localization

Perception of the location of a sound source.

kinesthesia

Sense for the awareness of positioning of body parts and body movement. Transduction in muscles, joints, and tendons

vestibular

Sense of body movement and position, including the sense of balance. Transduction in semicircular canals of inner ear. Monitors position of head and whole body

somatic senses

Senses of touch, temperature, pressure, pain, and kinesthesia which are perceived in the parietal lobes. Receptors are in the skin except for kinesthesia which in the muscles and joints.

papillae

Structures on tongue containing groups of taste receptors, or taste buds

Gibson and Walk

These two researchers studied infants' depth perception using the technique called the "visual cliff"

Ossicles

Three small bones found in the middle ear (malleus, incus, and stapes) that help to amplify the vibrations from sound waves. Malleus is attached to the tympanic membrane and stapes is attached to oval window of cochlea.

perceptual set

a readiness to perceive a stimulus in a particular way.

sensory deprivation

absence of normal levels of sensory stimulation - has been used for torture

subliminal

below one's absolute threshold for conscious awareness.

rods

cells in PERIPHERAL region of retina where transduction occurs. Best for dim light conditions; do NOT see in color

fovea

central focal point in retina, around which eye's cones cluster.

middle ear

chamber between eardrum and cochlea containing 3 tiny bones (hammer, anvil, and stirrup) that concentrate vibrations of eardrum on cochlea's oval window.

pheromones

chemicals released by one animal and detected by another that shape the second animal's behavior or physiology

transduction for vestibular sense

cilia in semi circular canals of the inner ear

cochlea

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

habituation

decreasing responsiveness with repeated (but not continuous) stimulation. As infants gain familiarity with repeated exposure to a visual stimulus, their interest wanes and they look away sooner

cochlear implant

device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.

change blindness

difficulty in recognizing alterations to the visual scene after a brief interruption.

hue

dimension of color determined by wavelength of light; what we know as color names blue, green, and so forth.

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

sensory adaptation

diminished sensitivity as a consequence of constant stimulation.

wavelength

distance from peak of one light or sound wave to peak of the next in light waves determines color and sound pitch

gate control theory

explanation for pain control that proposes we under some circumstances, incoming pain signals to the brain can be blocked in the spinal cord

A Delta fibers

fast neurons with myelinated axons on which sharp, and stinging pain impulses travel

foveal vision

part of our vision that is the sharpest because it involves the central part of the retina where cones are predominant.

color constancy

perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object.

parallel processing

perception of several aspects of a problem simultaneously; in vision brain's feature detectors fire simultaneously to create a perception of a visual scene. Contrasts with step-by-step (serial) processing of most computers and of conscious problem solving.

sensory interaction

principle that one sense may influence another, as when smell of food influences its taste.

light adaptation

process by which eyes become less sensitive to light in high illumination

sensation

process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.

accommodation

process by which the eye's lens changes shape to focus near or far objects on retina.

dark adaptation

process by which visual receptors become as sharp as they can in darkness. both rods and cones adjust but ultimately rods are more effective in darkness

perception

process of organizing and interpreting sensory info, enabling us to recognize meaningful objects and events.

Fechner

psychophysicist who showed ratio between physical intensity of a stimuli and its perceived intensity follows a logarithmic function

prosopragnosia

result of damage to areas in both the temporal and parietal lobes,that results in a difficulty in recognizing faces

chemical senses

smell and taste

bipolar cells

specialized cells which connect rods and cones to the ganglion cells of the optic nerve

ganglion cells

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

sensory overload

state of excessive and sustained multisensory stimulation manifested by behavior change and perceptual distortion - has been used for torture

psychophysics

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

kinesthesis

system for sensing the position and movement of individual body parts. This sense allows you to accurately touch your mouth, nose, and chin with your index finger with your eyes closed.

visual capture

tendency for vision to dominate other senses.

perceptual adaptation

the ability to adjust to an altered perceptual reality; in vision, the ability to adjust to an artificially displaced or inverted visual field (as when wearing visual displacement goggles)

Young-Helmholtz

theory that retina contains 3 different color receptors—red, green, & blue—which when stimulated in combination can produce perception of any color.

blind spot

the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there. (Myers Psychology 8e p. 207)

signal detection theory

theory predicting how and when we notice the presence of a faint stimulus amid background stimulation ("noise"). Assumes no single absolute threshold and detection depends on person's experience, expectations, motivation, and level of fatigue.

Weber's law

theory stating that the size of a just noticeable difference is a constant proportion of the size of the initial stimulus.

opponent-process theory

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.

Trichromatic theory

theory that retina contains 3 different color receptors—red, green, & blue—which when stimulated in combination can produce perception of any color also called Young-Helmholtz

gate-control theory

theory that spinal cord contains a neurological "door" that blocks pain signals or allows them to pass on to brain. "Door" is opened by activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by info coming from the brain.

pitch

tone's experienced highness or lowness that is determined by the frequency of the sound wave

lens

transparent structure behind the pupil that changes shape to help focus images on the retina.

semi-circular canals

tubes in the inner ear whose fluid, when shifted by head movements, stimulates nerve cells that tell the brain about those movement

additive color mixing

when all colors of light are mixed the result is white which is what results from combo of all visible wavelengths

subtractive color mixing

works when some wavelengths of light are removed leaving less light than was originally there.