Unit 1: Sensation

absolute threshold

minimal amount of energy required to produce any sensation, 50 percent of the time.

cochlea

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

cones

visual receptor cells; located in retina; works best in bright light; responsible for viewing color; greatest density in the fovea.

difference threshold

Just Noticeable Difference (JND); the smallest change in stimulation that you can detect 50% of the time; differs from one person to the other (and from moment to moment); tells us the flexibility of sensory systems.

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, as when we construct perceptions drawing on our experience and expectations.

inattentional blindness

failing to see visible objects when our attention is directed elsewhere

change blindness

failing to notice changes in the environment.

hue

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

iris

the color part of the eye; made of muscle that contracts/relaxes to control the size of the people allowing light to enter the eye.

kinesthesia

sense of muscle movement, posture, and strain on muscles/joints; provides information on speed and direction of movement; works with vestibular sense.

lens

transparent part of the eye behind the iris; focuses light on the retina (accommodation); change shape to focus on objects.

signal detection theory

States that circumstances, experiences, expectations affect our thresholds

sensory adaptation

diminished sensitivity as a consequence of constant stimulation.

opponent-process theory

created by Edward Hering; alternative theory used to explain after images; suggest that the retina contains three pairs color receptors or cones-yellow-blue, red-green, black-white; pairs work in opposition (thalamus)

wavelength

the distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from longer/red, shorter/blue.

optic nerve

bundle of axons from ganglion cells that carries messages from the eye to the brain.

intensity

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

parallel processing

the processing of several aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision, hearing.

pitch

auditory experience corresponding to the frequency of sound vibrations, resulting in a higher or lower tone.

place theory

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

pupil

small opening in the center of the iris.

retina

the light-sensitive inner lining of the back of the eyeball; contains receptor cells (rods/cones)

rods

visual receptor cell; located in retina; respond to varying degrees of light and dark; responsible for night vision and peripheral vision.

sensation

the raw data of experience; sensory stimulation; example are eyes only register light energy and ears only register wave energy.

fovea

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

audtition

The sense of hearing.

frequency

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

middle ear

The chamber between the eardrum and cochlea containing three tiny bones (Hammer, Anvil, and Stirrup) that concentrate the vibrations (conduction) of the eardrum on the cochlea's oval window.

conduction hearing loss

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

cochlear implant

a device for converting sounds into electrical signals and stimulating the auditory nerve by electrodes threaded into the cochlea

inner ear

the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.

frequency theory

in hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch.

vestibular sense

the sense of body movement and position, including the sense of balance.

olfaction

the sense of smell, which occurs when receptors in the nose respond to chemicals.

sensory interaction

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

Young-Helmholtz trichromatic (three-color) theory

the theory that the retina contains three different color receptors—one most sensitive to red, one to green, one to blue—which, when stimulated in combination, can produce the perception of any color.

accommodation

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

cornea

the eye's clear, protective outer layer, covering the pupil and iris.

sensory receptors

sensory nerve endings that respond to stimuli

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.

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)

Pheromones

biochemical odorants emitted by other members of their species that can affect an animal's behavior or physiology

Oleogustus

a primary taste sensation created by fatty acids

Dichromatism

the use of two types of cones instead of three. Most common type is red-green.

Monochromatism

color vision deficiency involving one cone instead of three. All vision is in shades of a single color.

Prosopagnosia

inability to recognize faces

ganglion cells

In the retina, the specialized neurons that connect to the bipolar cells; the bundled axons of the ganglion cells form the optic nerve.

sound localization

the process by which the location of sound is determined

farsightedness

a condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind the retina

nearsightedness

a condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of the retina

Synesthesia

describing one kind of sensation in terms of another ("a loud color", "a sweet sound")