Studied by 0 peopleReflex
a simple, automatic response to a sensory stimulus, such as the knee-jerk response.
Endocrine
the body's "slow" chemicalcommunication system; a set ofglands that secrete hormones intothe bloodstream.
Hormones
chemical messengersthat are manufactured by theendocrine glands travel through thebloodstream and affect other tissues.
Adrenal
a pair of endocrine glands thatsit just above the kidneys andsecrete hormones (epinephrine andnorepinephrine) that help arousethe body in times of stress.
Pituitary Glands
the endocrine system's most influential gland. Under the influence of thehypothalamus, the pituitary regulates growth and controls other endocrine glands.
Lesion
tissue destruction. A brain lesion is anaturally or experimentally causeddestruction of brain tissue.
Electroencephalogram
an amplified recording of the wavesof electrical activity sweepingacross the brain's surface. Thesewaves are measured by electrodesplaced on the scalp.
CT (Computed Tomography) Scan
a series of X-ray photographstaken from different angles andcombined by computer into acomposite representation of a sliceof the brain's structure. (Also calledCAT scan.)
PET (Positron Emission Tomography) Scan
a visual display of brain activity that detectswhere a radioactive form of glucose goes while the brain performs a given task.
MRI (Magnetic Resonance Imaging)
a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. MRI scansshow brain anatomy.
fMRI (Functional MRI)
a technique for revealing bloodflowand, therefore, brain activity bycomparing successive MRI scans.fMRI scans show brain function aswell as its structure.
Brainstem
the oldest part and central core of the brain, beginning where the spinal cord swells as itenters the skull; the brainstem is responsible for automatic survival functions.
Medulla
the base of the brainstem; controls heartbeat and breathing.
Thalamus
the brain's sensory control center,located on top of the brainstem;it directs messages to the sensoryreceiving areas in the cortex andtransmits replies to the cerebellumand medulla.
Reticular Formation
a nerve network that travels through thebrainstem and thalamus and playsan important role in controlling arousal.
Cerebellum
the "little brain" at the rear of the brainstem; functions include processing sensory input,coordinating movement output and balance, and enabling nonverbal learning and memory.
Limbic System
neural system (including the hippocampus,amygdala, and hypothalamus) located below the cerebral hemispheres; associated withemotions and drives.
Amygdala
two lima-bean-sized neural clusters inthe limbic system; linked to emotion.
Hypothalamus
a neural structure lying below(hypo) the thalamus; it directs severalmaintenance activities (eating,drinking, body temperature), helpsgovern the endocrine system viathe pituitary gland, and is linked toemotion and reward.
Cerebral
the intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body's ultimate control and information-processing center.
Glial Cells
cells in the nervous system that support,nourish, and protect neurons; theymay also play a role in learning andthinking.
Frontal Lobe
portion of the cerebral cortex lying just behind the forehead; involvedin speaking and muscle movements and in making plans and judgments.
Parietal Lobe
portion of the cerebral cortex lyingat the top of the head and towardthe rear; receives sensory input fortouch and body position.
Occipital Lobes
portion of the cerebral cortex lyingat the back of the head; includesareas that receive information fromthe visual fields.
Temporal Lobes
portion of the cerebral cortex lying roughly above the ears; includes the auditoryareas, each receiving informationprimarily from the opposite ear.
Motor Cortex
an area at the rear of the frontal lobes that controls voluntary movements.
Somatosensory Cortex
area at the front of the parietal lobes thatregisters and processes body touch and movement sensations.
Association Areas
areas of the cerebral cortex that are not involved in primary motor or sensoryfunctions; rather, they are involvedin higher mental functions such aslearning, remembering, thinking,and speaking.
Plasticity
the brain's ability to change, especially during childhood, by reorganizing afterdamage or by building new pathways based on experience.
Neurogenesis
the formation of new neurons.
Corpus Callosum
the large band of neural fibers connecting the two brain hemispheres and carryingmessages between them.
Split Brain
a condition resulting from surgery that isolates the brain's two hemispheres by cutting the fibers (mainly those of the corpuscallosum) connecting them.
Consciousness
our awareness of ourselves and our environment.
Cognitive Neuroscience
the interdisciplinary study of the brainactivity linked with cognition (including perception, thinking, memory, and language).
Dual Processing
the principle that information is oftensimultaneously processed on separate conscious and unconscious tracks.
Behavior Genetics
the study of the relative power and limitsof genetic and environmental influences on behavior.
Environment
every external influence, from prenatal nutrition to the people and things around us.
Chromosomes
threadlike structures made of DNA molecules that contain the genes.
DNA (deoxyribonucleic acid)
a complex molecule containing the genetic information that makes up the chromosomes.
Genes
the biochemical units of heredity that make up the chromosomes; segments of DNAcapable of synthesizing proteins.
Genome
the complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes.
Identical Twins
twins who develop from a single fertilized egg that splits in two, creating two genetically identical organisms.
Fraternal Twins
twins who develop from separate fertilized eggs. They are genetically no closer than brothers and sisters, but they share a fetal environment.
Molecular Genetics
the subfield of biology that studies themolecular structure and function of genes.
Heritability
the proportion of variation among individuals that we can attribute to genes. The heritability of a trait may vary, dependingon the range of populations and environments studied.
Interaction
the interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity).
Epigenetics
the study of environmental influences on gene expression that occur without aDNA change.
Evolutionary Psychology
the study of the evolution of behaviorand the mind, using principles of natural selection.
Natural Selection
the principle that, among the range of inherited trait variations, those contributingto reproduction and survival will most likely be passed on to succeeding generations.
Mutation
a random error in gene replication that leads to a change.
Sensation
the process by which our sensory receptors and nervoussystem receive and represent stimulus energies from ourenvironment.
Perception
the process of organizing and interpretingsensory information, enabling us to recognize meaningful objects and events.
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.
Selective Attention
the focusing of conscious awareness on a particular stimulus.
Inattentional Blindness
failing to see visible objects when our attention is directed elsewhere.
Change Blindness
failing to notice changes in the environment.
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 brain can interpret.
Psychophysics
the study of relationships between the physical characteristics of stimuli, such as their intensity, and ourpsychological experience of them.
Absolute Threshold
the minimum stimulation needed to detect a particular stimulus 50 percent of the time.
Signal Detection Theory
a theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation(noise). Assumes that there is no single absolute threshold and that detection depends partly on a person's experience, expectations, motivation, and alertness.
Subliminal
below one's absolute threshold for conscious awareness.
Priming
the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response.
Difference Threshold
the minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference (or jnd).
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).
Sensory Adaption
diminished sensitivity as a consequence of constant stimulation.
Perceptual Set
a mental predisposition to perceive one thing and not another.
Extrasensory Perception
the controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition.
Parapsychology
the study of paranormal phenomena, including ESP and psychokinesis.
Wavelength
the distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission.
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.
Intensity
the amount of energy in a light or sound wave, which weperceive as brightness or loudness, as determined by the wave's amplitude.
Pupil
the adjustable opening in the center of the eye through which light enters.
Iris
a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening.
Lens
the transparent structure behind the pupil that changes shape to help focus images on the retina.
Retina
the light-sensitive inner surface of the eye, containingthe receptor rods and cones plus layers of neurons that begin the processing of visual information.
Accommodation
the process by which the eye's lens changes shape tofocus near or far objects on the retina.
Rods
retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond.
Cones
retinal receptor cells that are concentrated near the centerof the retina and that function in daylight or in well-lit conditions. The cones detect fine detail and give rise to color sensations.
Optic Nerve
the nerve that carries neural impulses from the eye to thebrain.
Blind Spot
the point at which the optic nerve leaves the eye, creatinga "blind" spot because no receptor cells are located there.
Fovea
the central focal point in the retina, around which the eye'scones cluster.
Feature Detectors
nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.
Parallel Processing
the processing of many aspects of a problem simultaneously; the brain's natural mode of informationprocessing for many functions, including vision. Contrasts with the step-by-step (serial) processing of most computers and of conscious problem solving.
Young-Helmholtz trichromatic (three-color) theory
the theory that the retina contains three different color receptors—one most sensitive to red, one to green, oneto blue—which, when stimulated in combination, can produce the perception of any color.
Opponent-Process Theory
the 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.
Gestalt
an organized whole. Gestalt psychologists emphasizedour tendency to integrate pieces of information into meaningful wholes.
Figure-Ground
the organization of the visual field into objects (thefigures) that stand out from their surroundings (the ground).
Grouping
the perceptual tendency to organize stimuli into coherentgroups.
Depth Perception
the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allowsus to judge distance.
Visual Cliff
a laboratory device for testing depth perception in infantsand young animals.
Binocular Cues
depth cues, such as retinal disparity, that depend onthe use of two eyes.
Retinal Disparity
a binocular cue for perceiving depth: By comparingimages from the retinas in the two eyes, the brain computes distance—the greater the disparity (difference)between the two images, the closer the object.
Monocular Cues
depth cues, such as interposition and linear perspective, available to either eye alone.
Phi Phenomenon
an illusion of movement created when two or more adjacent lights blink on and off in quick succession.
Perceptual Constancy
perceiving objects as unchanging (having consistent shapes, size, brightness, and color) even as illumination andretinal images change.
Color Constancy
perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected bythe object.
Perceptual Adaptation
in vision, the ability to adjust to an artificially displaced or even inverted visual field.
Audition
The sense or act of hearing
Frequency
the number of complete wavelengths that pass apoint in a given time (for example, per secon
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