Biological Bases of Behavior Vocabulary

absolute threshold

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

accommodation

In vision, the process by which the lens of the eye shifts to focus on a particular object.

Afterimages

The image that remains after a stimulus ends or is removed. A positive afterimage occurs rarely, lasts a few seconds, and is caused by a continuation of receptor and neural processes following cessation of the stimulus; it has approximately the color and brightness of the original stimulus. A negative afterimage is more common, is often more intense, and lasts longer. It is usually complementary to the original stimulus in color and brightness; for example, if the stimulus was bright yellow, the negative afterimage will be dark blue.

amplitude

Magnitude or extent (e.g., of a stimulus) or peak value (e.g., of a sinusoid wave).

audition

The sense of hearing.

biological psychology

A branch of psychology concerned with the links between biology and behavior.

blind spot

The point at which the optic nerve leaves the eye, creating a small gap in the field of vision.

blindsight

A condition in which a person can respond to visual stimuli without consciously experiencing them.

bottom-up processing

Analysis that begins with sensory receptors and works up to the brain's integration of sensory information.

cochlea

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

cochlear implant

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

cognitive neuroscience

The interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language).

computed tomography (CT)

A scanning technique using multiple X-rays to construct a 3D image of the brain's structure.

conduction hearing loss or conduction deafness

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

cones

Photoreceptor cells in the retina that are responsible for color vision and fine detail. Red, Green, Blue.

cornea

The transparent outer layer of the eye that covers the pupil and iris and helps focus incoming light.

David Hubel

A Canadian neurophysiologist known for his work with Torsten Wiesel on the processing of visual information in the brain.

Dichromatism

Partial color blindness in which the eye contains only two types of cone photopigment instead of the typical three: Lack of the third pigment leads to confusion between certain colors. Red-green color blindness is the most common, whereas the blue-green variety is relatively rare.

difference threshold or Just-Noticeable Difference (JND)

The minimum difference between two stimuli required for detection 50% of the time; also known as just noticeable difference (JND).

dual processing

The idea that information is simultaneously processed on separate conscious and unconscious tracks.

embodied cognition

The theory that cognition is influenced by the body's interactions with the environment.

endorphins

Neurotransmitters that are natural painkillers produced by the brain.

Ernst Weber

A German physician credited with the formulation of Weber's law, which describes the relationship between the magnitude of a physical stimulus and the intensity of its perceived sensation.

Far Sightedness

Also called Hyperopia. It is a refractive error due to an abnormally short eyeball, which causes the image of close objects to be blurred because the focal point of one or both eyes lies behind, rather than on, the retina.

feature detectors

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

fovea

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

frequency

The number of complete wavelengths that pass a point in a given time.

frequency theory

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.

Ganglion Cells

The only type of neuron in the retina that sends signals to the brain resulting from visual stimulation. Retinal ganglion cells receive input from retinal bipolar cells and amacrine cells. The axons of retinal ganglion cells form the optic nerve.

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.

gustation

The sense of taste.

Gustav Fechner

A German psychologist known for his work in psychophysics, particularly his development of Weber's law and the concept of the just noticeable difference.

hindbrain

The lower part of the brainstem, comprising the medulla, pons, and cerebellum, responsible for basic life functions.

hue

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

inner ear

The innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs, involved in balance and hearing.

intensity

The amount of energy in a light or sound wave, which we perceive as brightness or loudness.

iris

The colored part of the eye that regulates the size of the pupil by controlling the amount of light entering the eye.

kinesthesis

The sense of the body's position and movement of body parts relative to each other.

lens

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

Loudness

The subjective magnitude of sound. It is determined primarily by intensity but is also affected by other physical properties, such as frequency, spectral configuration, and duration.

magnetic resonance imaging (MRI)

A technique that uses magnetic fields and radio waves to produce detailed images of the brain's soft tissue.

Medium tasters

Medium tasters sense the bitterness but don't mind it, while supertasters find the taste of PROP revolting.

middle ear

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

Monochromatism

A partial color blindness in which the eye contains only one type of cone photopigment instead of the typical three: Everything appears in various shades of a single color.

Near sightedness

Nearsightedness, a refractive error due to an abnormally long eye: The retinal image is blurred because the focal point of one or both eyes lies in front of, rather than on, the retina.

nervous system

The body's speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems.

neurotransmitters

Chemical messengers that transmit signals across the synaptic gap between neurons.

non tasters

Someone who has less taste perception than, say, a medium-taster who has an average ability to sense different flavors.

supertasters

those who experience taste with far greater intensity than most others

olfaction

the sense of smell

opponent-process theory

a theory of color vision proposing that the brain processes color information in pairs of complementary colors

optic nerve

the bundle of nerve fibers that carries visual information from the retina to the brain

parallel processing

the brain's ability to process multiple aspects of a problem or stimulus simultaneously

perception

the process of organizing and interpreting sensory information to recognize meaningful objects and events

Phantom Limb

the feeling that an amputated limb is still present, often manifested as a tingling or painful sensation

Pheromones

a chemical signal released outside the body by members of a species to influence the behavior of others

Photoreceptors

visual receptors like retinal rods or cones

Pitch

a tone's experienced highness or lowness depending on frequency

place theory

the theory linking the pitch we hear with the place where the cochlea's membrane is stimulated

positron resonance tomography (PET)

a brain imaging technique measuring brain activity by detecting radioactive glucose uptake in active brain areas

Prosopagnosia

a form of visual agnosia impairing the ability to perceive and recognize faces

psychophysics

the study of the relationship between physical characteristics of stimuli and our psychological experience of them

pupil

the adjustable opening in the center of the eye through which light enters

retina

the light-sensitive inner surface of the eye containing receptor cells and neurons for visual processing

rods

retinal receptors detecting black, white, and gray; necessary for peripheral and twilight vision

sensation

the process by which sensory receptors and the nervous system receive and represent stimulus energies

sensorineural hearing loss

hearing loss caused by damage to the cochlea's hair cells or the auditory nerve

sensory adaptation

diminished sensitivity to an unchanging stimulus over time

sensory interaction

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

Semicircular Canals

three looped tubular channels in the inner ear detecting head movements and providing balance

sequential processing

the processing of one aspect of a stimulus at a time, used for new or complex tasks

signal detection theory

a theory predicting how and when we detect faint stimuli amid background noise

Sweet, sour, salty, bitter, umami, oleo Gustus

the five basic tastes that inform us about what we put into our mouth, with oleo Gustus being an oily or fatty taste

Synesthesia

a condition where stimulation of one sense generates a simultaneous sensation in another

Sound localization

the ability to identify the position and changes in position of sound sources based on acoustic information

subliminal

below one's absolute threshold for conscious awareness

Thalamus

the body's information relay station for processing sensory information before sending it to the brain

top-down processing

information processing guided by higher-level mental processes, drawing on experience and expectations

Torsten Wiesel

a Swedish neurophysiologist known for collaborative work elucidating the visual processing system

transduction

the process of converting sensory stimuli into neural impulses

Trichromatic theory

a concept of color vision based on experiments showing hues matched by a mixture of three primary colors

Visual nerve

connects the retina to the visual cortex in the back of the brain

vestibular sense

the sense of body movement and position, including balance

Volley theory

the principle that individual fibers in an auditory nerve respond to rhythmic sound stimuli in rapid succession

Warm/Cold receptors

thermoreceptors found in the dermis registering hot or cold sensations

wavelength

the distance from the peak of one wave to the peak of the next, determining color in vision or pitch in audition

Weber's Law

the principle that two stimuli must differ by a constant minimum percentage to be perceived as different