aberration: wandering; extreme deviation from the norm, especially from truth or moral rectitude, from the natural state, or from a type; partial alienation of reason; insaninity, lunacy, madness, derangement, alienation, mania, dementia, hallucination, illusion, delusion.

ability [L. habilitas => aptitude, ability]: demonstrable knowledge or skill; quality or state of being able; physical, moral or intellectual power to perform; capacity; skill or competence in doing; sufficiency of strength, skill, resources, etc.; includes aptitude and achievement.

abreaction: Psychoanalysis) process of reducing emotional tension by relieving (in speech or action or both) the experience that caused the tension.

absolute threshold: intensity or frequency at which a stimulus becomes effective or ceases to become effective, as measured under experimental conditions. See) difference threshold, threshold.

accommodation: Eye) process by which the lens of the eye varies its focus. Piaget's theory of cognitive development) process by which an infant modifies a pre-existing schema in order to include a novel object or event. See) assimilation.

acetylcholine: most common of neurotransmitters. It is found in many synapses in the brain and spinal cord, and is particularly prevalent in an area of the brain called the hippocampus, which plays a key role in the formation of new memories.

achievement: an acquired ability obtained through some level of effort. See) aptitude.

achromatic colors: black, white, and gray. See) chromatic colors.

acoustic buffer: Short-term Memory) hypothesized component of the encoding process which briefly stores information in an acoustic code (eg, the sound of the digit, letter, or word). See) central executive, visual buffer.

acquisition: stage during which a new response is learned and gradually strengthened. See) classical conditioning.

action potential (nerve impulse): wave of electrical activity that is transmitted down the axon of the neuron when the cell membrane becomes depolarized.graded potentials, resting potential.

activation:

activation model: Memory) the proposal that retrieval of an item depends on the activation of that item reaching a critical level.

acupuncture: A healing procedure developed in China in which needles are inserted in the skin at critical points and twirled, eliminating pain.gate control theory of pain.

adaptive behaviors:

addiction: See drug dependence.

additive color mixture: lights of different colors focused on the same spot yield an additive color mixture; mixture of colored lights.subtractive mixture.

adipocytes: special fat cells in the body; obese individuals have many more which may cause a higher body fat base line.

adolescence: period of transition from childhood to adulthood during which the individual develops to sexual maturity. See) puberty.

adolescent growth spurt: period of rapid physical growth that accompanies puberty.

adrenal cortex:

adrenal-cortical-system: neuro-endocrine system activated in response to stress. On a signal from the hypothalamus, the pituitary gland secretes a number of hormones. One stimulates the thyroid gland to make more energy available; the other (adrenocorticotropic hormone, ACTH) triggers the outer layer of the adrenal gland (the adrenal cortex) to release some 30 hormones (including cortisol) which play a role in the body's adjustment to emergencies.

adrenal gland: One of a pair of endocrine glands located above the kidneys. The medulla of the gland secretes the hormones epinephrine and norepinephrine. The cortex of the gland secretes a number of hormones, collectively called the adrenocortical hormones, which include cortisol. See) endocrine system.

adrenalin: See epinephrine.

adrenal medulla:

adrenocorticotropic hormone (ACTH): hormone released by the pituitary gland in response to stress; known as the body's major 'stress' hormone. It is carried by the bloodstream to the adrenal glands and various other organs of the body, causing the release of some 30 hormones, each of which plays a role in the body's adjustment to emergency situations. See) corticotropin-release factor.

aerobic exercise: Any sustained activity that increases oxygen consumption, such as jogging, swimming, cycling, or fast walking.

affect: The experience of (hedonic) pleasure or of (aversive) displeasure or pain.

affective experience: An emotional experience, whether pleasant or unpleasant, mild or intense. See) emotion.

afterimage: The sensory experience that remains when a stimulus is withdrawn. Usually refers to visual experience?for example, the negative afterimage of a picture or the train of colored images that results after staring at the sun.

age regression: In hypnosis, the reliving through fantasy of experiences that are based on early memories or that are appropriate to a younger age. See) hypnosis.

aggregated score: A combination of several measures of the same behavior or characteristic.

aggression: Behavior intended to harm another person.

agnosia: A perceptual disturbance, resulting from damage to the cerebral cortex, in which the individual has difficulty identifying familiar objects even though visual acuity is normal. People suffering from agnosia appear to perceive but are not capable of understanding the information presented to them. See) associative agnosia, prosopagnosia.

agoraphobia: Fear of being alone or being in a public place where escape might be difficult or help unavailable should the individual be incapacitated by a panic attack. See) panic disorder, phobia.

all-or-none principle: The rule that the nerve impulse in a single neuron is independent of the strength of stimulation; the neuron either responds completely (fires its action potential) or not at all.

alpha waves: See electroencephalogram.

alternate form reliability: The consistency between two or more versions of the same test when given to the same person. See) reliability.

ambivalence: Simultaneous liking and disliking of an object or person; the conflict caused by an incentive that is at once positive and negative. See) conflict.

Ames room: A perceptual illusion; specifically, a room that when viewed through a peephole leads to distortions in size judgments. See) size constancy.

amnesia: A partial or complete loss of memory. May be due to psychological factors (for example, emotional trauma) or physiological factors (some form of brain damage) and may involve loss of memory for events occurring prior to or subsequent to the amnesia-causing trauma. See) anterograde amnesia, retrograde amnesia.

amphetamines: Central nervous system stimulants that produce restlessness, irritability, anxiety, and rapid heart rate. Dexedrine sulfate ('speed') and methamphetamine ('meth') are two types of amphetamines. See) depressants, stimulants.

amygdala: A brain structure located below the cerebral cortex that is involved in consolidation of emotional memories. See) diencephalon, hippocampus.

anal stage: The second stage in Freud's psychoanalytic theory of psychosexual development, following the oral stage. The sources of gratification and conflict have to do with the expulsion and retention of feces. See) psychosexual development.

analgesia:

androgen: A male hormone.

androgens: collective name for male sex hormones, of which testosterone, secreted by the testes, is best known. See) gonads.

anger:

angiotensin: A hormone that induces the feeling of thirst as well as an appetite for salt, which leads to behavioral adjustments.

Anorexia nervosa: A pathological desire not to gain weight; distinguished by an extreme, self-imposed weight loss. Dangerous side effects include emaciation, susceptibility to infection, and other symptoms of undernourishment.

anterior attentional system: Neural structures in the front of the brain that mediate our ability to selectively attend to some attribute of an object (other than its location).

anterograde amnesia: Loss of memory for events and experiences occurring subsequent to an amnesia-causing trauma; the patient is unable to acquire new information, although recall of information learned prior to the onset may be largely unaffected. See) retrograde amnesia.

anthropology: science that studies chiefly preliterate societies. Its main divisions are archaeology (the study of the physical monuments and remains from earlier civilizations), physical anthropology (concerned with the anatomical differences among people and their evolutionary origins), linguistic anthropology, and social anthrophology (concerned with social institutions and behavior). See) behavioral sciences.

antianxiety drug: Central nervous system depressant (belonging to the family of drugs called benzodiazapines) that reduces anxiety and tension. Causes some drowsiness but less than barbituates. Diazepam (Valium) and alprozolam (Xanax) are examples (syn. tranquilizer).

antidepressant: Drug used to elevate the mood of depressed individuals, presumably by increasing the availability of the neurotransmitters norepinephrine and/or serotonin. Examples are imipramine (Tofranil), isocarboxazid (Marplan), and tranylcypromine (Parnate).

antigen:

antidiuretic hormone (ADH): A hormone that regulates the kidneys so they release water back into the bloodstream and form only very concentrated urine.

antipsychotic drug (neuroleptic drug): reduces psychotic symptoms, used more frequently in the treatment of schizophrenia.  Examples) phenothiazines, such as chlorpromazine (Thorazin) and fluphenazine (Prolixin).

antisocial personality: A type of personality disorder marked by impulsivity, inability to abide by the customs and laws of society, and lack of anxiety or guilt regarding behavior (syn. sociopathic personality, psychopathic personality).

anxiety: state of apprehension, tension, and worry. Synonymous with fear for some theorists, although others view the object of anxiety (such as a vague danger or foreboding) as less specific than the object of a fear (such as a vicious animal). See) neurotic anxiety, objective anxiety.

anxiety disorders: group of mental disorders characterized by intense anxiety or by maladaptive behavior designed to relieve anxiety. Includes generalized anxiety and panic disorders, phobic and obsessive-compulsive disorders. Major category of DSM-IV covering most of the disorders formerly called neuroses. See) neurosis, post-traumatic stress disorder.

anxiety hierarchy: situations or stimuli to which a person responds with anxiety ranked in order from the least anxiety-producing to the most fearful. Used by behavior therapists in systematically desensitizing patients to feared stimuli by associating deep relaxation with the situations rather than anxiety.

apathy: listlessness, indifference; one of the consequences of frustration.

aphagia: inability to eat. See) hyperphagia.

aphasia: Impairment or loss of ability to articulate words or comprehend speech.

apnea: A sleep disturbance characterized by inhibited breathing during sleep.

apparent motion: See phi phenomenon, stroboscopic motion.

appetitive behavior: seeking behavior. See) aversive behavior.

appraisal theories of emotion: A group of theories of emotions stating that people's cognitive appraisals of situations determine the emotions they experience in response to the situations.

appraisals: Evaluations of a situation, event, person, or the self.

aptitude: capacity to learn; natural or acquired disposition or capacity for a particular purpose; tendency to a particular action or effect. See) achievement.

aptitude test: designed to predict the result of applied training, hence to predict future ability on the basis of present measurable ability, capability or aptitude.

arousal level: The principle according to which people seek an optimal level of drive or arousal.

artificial intelligence (AI): field of research combining computer science and cognitive psychology; it is concerned with (a) using computers to simulate human thought processes and (b) devising computer programs that act intelligently and can adapt to changing circumstances. In essence, it is the science of making machines (computers) do things that are normally done by the human mind. See) cognitive science

assertiveness training: use of behavioral rehearsal to help an individual learn to express his or her needs in an effective, nonhostile manner.

assimilation: Piaget's theory of cognitive development) process by which an infant comprehends a novel object or event in terms of a pre-existing schema.  See) accommodation

association areas: Areas of the cerebral cortex that are not directly concerned with sensory or motor processes; they integrate inputs from various sensory channels and presumably function in learning, memory, and thinking.

associative agnosia: perceptual disturbance, resulting from damage to specific areas of the cerebral cortex, in which the individual has difficulty recognizing familiar objects presented visually, although he or she can readily name the objects if allowed to touch or hear them. See) agnosia, prosopagnosia.

associative learning: Learning that certain contingencies (or relations) exist between events; learning that one event is associated with another.

astigmatism: vision) optical defect preventing horizontal and vertical contours from being in focus simultaneously. See) strabismus.

attachment: The tendency of the young organism to seek closeness to particular individuals and to feel more secure in their presence.

attention: focusing of perception leading to heightened awareness of a limited range of stimuli. It has both overt behavioral components and internal components. See) orienting reflex.

attitude: A like or dislike; a favorable or unfavorable evaluation of and reaction to an object, person, event, or idea: An attitude comprises a cognitive component, an affective component, and a behavioral component.

attribution (& attribution theory): process by which we attempt to explain the behavior of other people; theory that deals with the rules people use to infer the causes of observed behavior. See) dispositional attribution, situational attribution.

attributional style: one's characteristic way of giving causal explanations (attributions) for important events. People with a pessimistic attributional style, who attribute negative events to causes that are internal, stable over time, and global, are presumably more prone to depression than people with a more optimistic style who attribute such events to external, temporary, and specific causes.

auditory area: A brain region located at the top of the temporal lobe of each cerebral hemisphere where auditory signals carried by the acoustic nerve are analyzed. Because nerve fibers from each side of the head cross over at the brain stem before reaching the auditory area, signals from each ear reach both temporal lobes. Thus, damage to one lobe does not produce deafness in one ear.

auditory nerve:

authoritarian personality: A personality type who is submissive and obedient to superiors but contemptuous of and aggressive toward those he or she considers inferior. Shows prejudice against minority groups. The Authoritarian Personality is a classic social psychological study, based in psychoanalytic theory, which examined this personality type. See autism: A mental disorder, first evident during early childhood, in which the child shows significant deficits in communication, social interaction, and bonding and play activities, and engages in repetitive stereotyped behaviors and self-damaging acts.

automatic writing: that which the writer is unaware of (does not know that he or she is producing); familiar in hypnosis.

autonomic nervous system: division of the peripheral nervous system that performs involuntary functions; regulates smooth muscle (organ and glandular) activities. It is divided into the sympathetic and parasympathetic divisions.

average: See measure of central tendency.

aversive behavior: avoidance behavior. See) appetitive behavior

avoidance learning: learning to make a response to a warning signal in order to avoid an aversive event. See) escape learning.

awareness:  See) consciousness.

axon: portion of a neuron that transmits impulses to other neurons. See) dendrite.

BAC: See blood alcohol concentration.

Broca's area: A portion of the left cerebral hemisphere involved in the control of speech. Individuals with damage in this area have difficulty enunciating words correctly and speak in a slow and labored way; their speech often makes sense, but it includes only key words.

basal mental age: Binet type tests) the highest age level at which, and below which, all tests are passed. See) mental age.

base-rate rule: Probability Theory) that the probability of an object being a member of a class is greater the more class members there are. This rule is often violated in common real-world reasoning situations.

basic level: Hierarchy of Concepts) level at which one first categorizes an object.

basilar membrane: A membrane of the ear within the coils of the cochlea supporting the organ of Corti. Movements of the basilar membrane stimulate the hair cells of the organ of Corti, producing the neural effects of auditory stimulation. See) cochlea.

behavior: activities that can be observed by another, or by an experimenter's instruments, or verbal reports about one's own subjective, conscious experiences. See) conscious processes.

behavior genetics: The study of the inheritance of behavioral characteristics.

behavior modification: See behavior therapy.

behavior therapy (behavior modification): method of psychotherapy based on learning principles utilizing echniques such as counterconditioning, reinforcement, and shaping to modify behavior . See) cognitive behavior therapy.

behavioral medicine: The study of how social, psychological, and biological factors interact to contribute to physical illness (syn. health psychology).

behavioral perspective: approach to psychology that focuses only on observable behavior, and its explaination in terms of environmental events. See) behaviorism.

behavioral rehearsal: technique used in behavior therapy whereby the individual rehearses, or role-plays, more adaptive behaviors. See) assertiveness training.

behaviorism: A school or system of psychology associated with the name of John B. Watson; it defined psychology as the study of behavior and limited the data of psychology to observable activities. In its classical form it was more restrictive than the contemporary behavioral viewpoint in psychology.

belief-driven learning: associative learning by which people have prior beliefs about the relation that has to be learned; learning is driven by the beliefs as well as by the input. See) data-driven learning.

benzodiazepines: class of drugs, effective in reducing anxiety, which have similar chemical structures.  Examples) diazepam (Valium) and alprozolam (Xanax).  See) antianxiety drug.

binocular cues: See distance cues.

binocular disparity: A cue to depth perception that arises because an object projects slightly different images on the two retinas (due to the different positions of the right and left eyes).

binocular parallax: Vision) cue to depth perception whereby any visible point differs slightly in direction with respect to each eye. See) binocular disparity.

biofeedback: procedure permitting one to monitor one's own normally unconscious physiological processes (eg, heart rate and blood pressure) and to learn to control them.

biological perspective: explainations of behavior in terms of internal biological electrical and chemical events, particularly within the brain and nervous system.

biological psychologist (physiological psychologist): one concerned with the relationship between biological processes and behavior.

biological therapy: treatment of emotional problems or mental disorders by drugs, electric shock, or other methods directly affecting bodily processes. See) psychotherapy.

bipolar cells: Vision, Eye) in the retina that transmit electrical impulses from photoreceptors to ganglion cells.

bipolar disorder (manic-depression): mood disorder in which people experience episodes of depression and mania (exaggerated excitement) or of mania alone. Typically the individual alternates between the two extremes, often with periods of normal mood in between . See) mood disorder.

blind spot: An insensitive area of the retina where the nerve fibers from the ganglion cells join to form the optic nerve.

blocking: A phenomenon in classical conditioning: if one conditioned stimulus reliably predicts an unconditioned stimulus, and another conditioned stimulus is added, the relation between the added conditioned stimulus and the unconditioned stimulus will not be learned.

blood alcohol concentration (BAC): The concentration, in milligrams, of alcohol per 100 milliliters of blood. The legal definition of intoxication in most states is a blood alcohol concentration of .10 percent (100 milligrams of alcohol per 100 milliliters of blood).

blood pressure: The pressure of the blood against the walls of the blood vessels. Changes in blood pressure following stimulation serve as one indicator of emotion.

borderline personality disorder: A mental disorder in which the individual has manifested unstable moods, relationships with others, and self-perceptions chronically since adolescence or childhood.

bottom-up processes: driven solely by the information input, and that do not involve prior knowledge and expectations; applied to perception, learning, memory, and comprehension. See) top-down processes.

brain stem: essentially all of the brain with the exception of the cerebrum and the cerebellum and their dependent parts; structures lying near the core of the brain.

bulimia:: A pathological desire not to gain weight; characterized by recurrent episodes of binge eating (rapid consumption of a large amount of food in a discrete period of time), followed by attempts to purge the excess eating by means of vomiting and laxatives.

caffeine: [Turk. qahveh, Ar. qahuah wine G. Kaffee, Fr. café]: an alkaloid used as a stimulant, metabolized in the liver, the residue of which is excreted through the kidney, half life of caffeine in an adult is about 3 to 4 hours, slower when on oral contraceptives, in pregnancy, up to 18 hours.  Examples:) found naturally in coffee beans, tea leaves, cocoa beans (chocolate) and kola nuts (cola)  Uses:) added to soft drinks, foods, and medicines  Dosage:) 100-200 mg. caffeine can increase alertness, relieve drowsiness and improve thinking. At doses of 250-700 mg/day, caffeine can cause anxiety, insomnia, nervousness and hypertension; a cup of coffee has 100-250 mg; Black tea 40-100 mg; Green tea 15-30 mg  Relevance:) can help relieve some headaches, some over-the-counter and prescription pain relievers include it, usually with aspirin or another analgesic; a diuretic which increases urination

Cannon-Bard theory: Classical Theory) that an emotion-producing stimulus activates the cortex and bodily responses at the same time; bodily changes and the experience of emotion occur simultaneously. Proposed by Cannon and Bard.  See) cognitive-appraisal theory, James-Lange theory.

cannabis: hemp plant from which marijuana is obtained.

cardiac muscle: special type of muscle found only in the heart. See) smooth muscle, striate muscle.

case history: biography collected for the purpose scientific study. See) longitudinal study.

castration: removal of the gonads; in the male, removal of the testes; in the female, removal of the ovaries.

catatonic immobility: fixity of posture maintained for long periods with accompanying muscular rigidity and a trance-like state of consciousness. A symptom in some cases of schizophrenia.

categorization: assigning an object to a conceptual construct or classification.

catharsis: relieving an abnormal excitement by re-establishing the association of the emotion with the memory or idea of the event that first caused it, and of eliminating it by complete expression (the abreaction); reduction of an impulse or emotion through direct or indirect expression, particularly verbal and fantasy expression. Medicine) natural or artificial purgation of any passage, as of the mouth, bowels, etc.

cell-assembly: Donald O. Hebb's 1949 coinage for a group of cortical neurons that subserves and sustains the active memory trace that follows perception.

central core: Brain) central and oldest evolutionally portion of the brain, including most of the brain stem and structures regulating basic life processes. See) cerebellum, hypothalamus, reticular formation.

central executive: Short-term Memory) (hypothesized) component of the encoding process that coordinates the acoustic and visual buffers.

central fissure (fissure of Rolando): fissure of each cerebral hemisphere that separates the frontal and parietal lobes.

central nervous system: Vertebrates) brain and spinal cord, as distinct from the nerve trunks and their peripheral connections; the brain, spinal cord, and the retina (the remainder is the peripheral nervous system). See) autonomic nervous system.

cerebellum: lobed structure attached to the rear of the brain stem that regulates muscle tone and coordination of intricate movements, such as in the control of balance and posture.

cerebral cortex (cerebral mantle) (cerebrum) (cortex) (pallium) (commonly called gray matter) { Figure }: surface layer of the cerebral hemispheres responsible for conscious experience, including perception, emotion, thought, and planning, as well as coordination of motor activity (called gray matter because its gray appearance in cross section in contrast with the white matter (myelinated nerve fibers) in the center.

cerebral hemispheres (cerebrum): two large masses of nerve cells and fibers constituting the bulk of the brain in humans and other higher animals. The hemispheres are separated by a deep fissure, but connected by the corpus callosum (cerebrum). See) cerebral cortex, left hemisphere, right hemisphere, split-brain subject.

childhood amnesia: inability to recall events from the first years of one's life.

chlorpromazine:  See) antipsychotic drug.

chromatic colors (spectral colors): all colors other than the achromatic colors (black, white, and grays); for instance, red, yellow, blue.

chromosome: rodlike structures found in pairs in all the cells of the body, carrying the genetic determiners (genes) that are transmitted from parent to offspring. A human cell has 46 chromosomes, arranged in 23 pairs, one member of each pair deriving from the mother, one from the father.

chronological age (CA): calendar age from birth. See) mental age.

chunk: Short-term Memory) largest meaningful unit of information that can be stored in short-term memory, which holds 762 chunks.

cilia: hairlike structures that are sometimes parts of receptors.

circadian rhythm: cycle or rhythm roughly 24 hours long whch is followed by our sleep-wakefulness, body temperature, water excretion and other behavioral and psychological variables.

clairvoyance: perception of objects or events that do not provide a stimulus to the known senses. See) extrasensory perception, parapsychology, precognition, psi, psychokinesis, telepathy.

classical concept: where each instance defined by a concept must have every property that represents the definition of the concept. An example is that every instance of a book must have the properties of providing information conveyed by written language or symbols. See) fuzzy concept.

classical conditioning: conditioned response conforming to the pattern of Pavlov's experiment. The main feature is that the originally neutral conditioned stimulus, through repeated pairing with the unconditioned one, becomes associated with the unconditioned stimulus. See) operant conditioning.

claustrophobia: fear of closed places. See) phobia.

client-centered therapy (person-centered therapy) (nondirective counseling): Psychotherapy) method under the operating assumption that the client is equipped to solve existing problems when provided a nonjudgmental, accepting atmosphere; the therapist is nondirective and reflective and does not interpret or advise; developed by Carl Rogers. See) humanistic therapies.

clinical psychologist: one trained in the diagnosis and treatment of emotional or behavioral problems and mental disorders, generally having a Ph.D. or Psy.D. degree. See) counseling psychologist, psychiatrist.

cocaine: a central nervous system stimulant derived from leaves of the coca plant which increases energy, produces a feeling of euphoria and in large doses causes paranoia.

cochlea: Inner Ear) portion containing the receptors for hearing. See) basilar membrane.

coding: See encoding.

coding by pattern: coding the quality of a sensation in terms of the pattern of neural firing. See) coding by specificity.

coding by specificity: coding the quality of a sensation in terms of the specific neurons involved. See) coding by pattern, specific nerve energies.

coefficient of correlation: numerical index indicating degree of correspondence between two sets of paired measurements. The most common kind is the product-moment coefficient designated by r.

cognition: one's thoughts, knowledge, interpretations, understandings, or ideas. See) cognitive processes.

cognitive appraisal: interpretation of an event or situation with respect to one's goals and well-being. The cognitive appraisal of an event influences both the quality and intensity of the emotion experienced and the degree of perceived threat.

cognitive-appraisal theory: proposes that the subjective emotional state is a function of the individual's appraisal, or analysis, of the emotion-arousing situation. A state of physiological arousal can produce different emotions (even antithetical ones) depending on how the person appraises the situation. See) Cannon-Bard theory, James-Lange theory.

cognitive behavior therapy: Psychotherapy) emphasizes the influence of a person's beliefs, thoughts, and self-statements on behavior. Combines behavior therapy methods with techniques designed to change the way the individual thinks about self and events.

cognitive distortions: In Beck's theory of depression, systematic errors in thinking that lead depressed individuals to misperceive reality in a way that contributes to their negative self-schema. Examples are overgeneralization (drawing a sweeping conclusion on the basis of a single negative event) and selective abstraction (focusing on an insignificant negative detail while ignoring the more important positive features of a situation). See) depression, self-schema.

cognitive map: Memory) hypothetical structure that preserves and organizes (information about the) events in a learning situation; a mental picture of the learning situation. See) schema.

cognitive neuroscience: interdisciplinary approach that combines aspects of cognitive psychology and neuroscience to study how mental activities are executed in the brain.

cognitive perspective: Psychology) focuses on mental processes such as perceiving, remembering, reasoning, deciding, and problem solving, and tries to explain behavior in terms of these mental processes. See) cognitive psychology, cognitive science.

cognitive processes: mental processes of perception, memory, and information processing by which the individual acquires information, makes plans, and solves problems.

cognitive psychology: Psychology) focuses on mental processes in understanding behavior; explainations of behavior at the level of mental representations and the mental processes that operate on these representations to produce products (including responses). In recent years the approach has been generalized to all areas of psychology and not restricted to the study of thought and knowledge, although its early concerns with these topics led to the term cognitive psychology. See) artificial intelligence, cognitive science, information-processing model.

cognitive response theory: proposes that persuasion induced by a communication is actually self-persuasion produced by the thoughts that the individual generates while receiving or even just anticipating the communication.

cognitive science: study of cognition, or how humans acquire and organize knowledge; relevant disciplines are psychology, neuroscience, linguistics, philosophy, mathematics, and computer science (particularly artificial intelligence). Term was introduced in the 1970's. See) cognitive psychology.

cognitive triad: Beck's theory) negative thoughts about the self, the present situation, and the future which is the major concomitant, and possibly cause, of depression.

color blindness: defective discrimination of chromatic colors. See) dichromatism, monochromatism, red-green color blindness, trichromatism.

color circle: arrangement of chromatic colors on the circumference of a circle in the order in which they appear in the spectrum (with the addition of nonspectral reds and purples) arranged so that colors opposite each other are complementaries in additive mixture. See) color solid.

color constancy: The tendency to see a familiar object as of the same color, regardless of changes in illumination on it that alter its stimulus properties. See) perceptual constancy.

color solid: three-dimensional representation of the psychological dimensions of color, with hue around the circumference, saturation along each radius, and brightness from top to bottom. See) color circle.

color-opponent cells: Color Vision) cells that respond only to their two opponent colors. See) opponent-color theory.

companionate love: affection characterized by trust, caring, warmth, affection and a tolerance of flaws and idiosyncrasies; felt for those with whom one's life is deeply intertwined. Contrasted with passionate love.

complementary colors: two colors that in additive mixture yield either a gray or an unsaturated color of the hue of the stronger component.

complex cell: Visual Cortex) responds to a bar of light or straight edge of a particular orientation located anywhere in the visual field. See) simple cell.

complex learning: Learning that involves more than forming associations; for example, using a strategy to solve a problem or forming a mental map of one's surroundings. Contrasted with habituation and conditioning which are simpler types of learning. See) classical conditioning, habituation, operant conditioning.

compliance: publicly conforming to the wishes of an influencing source but not necessarily changing one's private beliefs or attitudes. See) identification, internalization.

compulsion: repetitive action that one feels driven to make and unable to resist; ritualistic behavior. See) obsession, obsessive-compulsive disorder.

computer program: See program.

computer simulation (:sometimes also referred to as simulation): The use of a computer to simulate a phenomenon or system in order to study its properties. In psychology, the simulation usually involves an attempt to program a computer to mimic how the mind processes information and solves problems. In this sense, the computer program is literally a theory of how the mind functions. See) artificial intelligence, cognitive psychology, information-processing model.

computerized axial tomography (CT): A computer-based procedure that analyzes data obtained by a scanning beam of X rays to provide a picture of a cross-sectional slice through the body or brain.

concept: The properties or relationships common to a class of objects or ideas. Concepts may be of concrete things (such as the concept poodle referring to a given variety of dog) or of abstract ideas (such as equality, justice, number). See) classical concept, fuzzy concept.

concomitant [L. con- + comitari to accompany, comes, companion]: accompanying; conjoined; attending.

concrete operational stage: Piaget's third stage of cognitive development (ages 7 to 11 years) during which a child becomes capable of logical thought and achieves conservation concepts. See) conservation.

conditioned emotion: An emotional response acquired by conditioning: one aroused by a stimulus that did not originally evoke it. See) conditioning.

conditioned fear: A fear acquired by classical conditioning. The object that the organism comes to fear was originally neutral, but when it is repeatedly paired with an aversive stimulus it becomes an object of fear.

conditioned reinforcer: A stimulus that has become reinforcing through prior association with a reinforcing stimulus (syn. secondary reinforcer). See) reinforcing stimulus.

conditioned response (CR): In classical conditioning, the learned or acquired response to a conditioned stimulus; in other words, to a stimulus that did not evoke the response originally. See) conditioned stimulus, unconditioned response, unconditioned stimulus.

conditioned stimulus (CS): In classical conditioning, a stimulus previously neutral that comes to elicit a conditioned response through association with an unconditioned stimulus. See) conditioned response, unconditioned response, unconditioned stimulus.

conditioning: The process by which conditioned responses are learned. See) classical conditioning, operant conditioning.

conduction loss: A hearing deficit in which threshold elevation (loss of sensitivity) occurs equally at all frequencies as the result of poor conduction in the middle ear. See) sensory-neural loss.

cone: Eye) a specialized cell of the retina found predominantly in the fovea and more sparsely throughout the retina. The cones mediate both chromatic and achromatic sensations; one of the two major classes of photoreceptors, the other being rods. Cones are less sensitive to light than rods and mediate color vision.

conflict: The simultaneous presence of opposing or mutually exclusive impulses, desires, or tendencies. See) ambivalence.

conjunction rule: A rule in probability theory, which states that the probability of a proposition cannot be less than the probability of that proposition conjoined with another proposition. People frequently violate the rule when reasoning about real-world situations.

connectionist models: Models of cognitive processes (like perception) that incorporate a network of nodes, with excitatory and inhibitory connections between them.

connotative meaning: The suggestive and emotional meanings of a word or symbol, beyond its denotative meaning. Thus, naked and nude both refer to an unclothed body (denotative meaning), but they have somewhat different connotations.

conscience: An internal recognition of standards of right and wrong by which the individual judges his or her conduct. See) superego.

conscious: In Freud's topographic model, the part of the mind containing thoughts and memories of which the individual is currently aware. See) preconscious, topographic model, unconscious.

conscious processes: Events such as perceptions, private thoughts, and dreams, of which only the person is aware. They are accessible to others through verbal report or by way of inference from other behavior (syn. experience, awareness).

consciousness: We are conscious when we are aware of external events, reflect on past experiences, engage in problem solving, are selective in attending to some stimuli rather than others, and deliberately choose an action in response to environmental conditions and personal goals. In short, consciousness has to do with a) monitoring ourselves and our environment so that percepts, memories, and thoughts are accurately represented in awareness; and b) controlling ourselves and our environment so that we are able to initiate and terminate behavioral and cognitive activities. In some contexts, the term is used as a synonym for awareness.

conservation: Piaget's term for the ability of the child to recognize that certain properties of objects (such as mass, volume, number) do not change despite transformations in the appearance of the objects. See) preoperational stage.

construct validity: The ability of a test or assessment instrument to confirm predictions of the theory underlying some theoretical concept or construct. Confirming results validate both the concept and the assessment instrument simultaneously. See) criterion problem, validity.

constructive memory: The memory that results when we use general knowledge construct and elaborate a more complete and detailed account of some event.

contrast sensitivity: In visual perception, the ability to discriminate between dark and light stripes under various conditions.

contrast threshold:

control group: In an experimental design contrasting two groups, that group not given the treatment whose effect is under study. See) experimental group.

control processes: Regulatory processes that serve to establish equilibrium or monitor goal-directed activities. See) homeostasis.

controlled stimulation: Conditions in which the perceptual experiences of an organism are systematically varied in order to determine the effect on subsequent performance. For example, rearing kittens in an environment where they see only vertical stripes for the first few months of life or having humans wear prism goggles that distort the directions of objects.

core: The part of a concept that contains the properties that are more essential for determining membership in the concept. See) prototype.

cornea: The transparent surface of the eye through which light enters and rays are bent inward to begin image formation. See) lens, pupil, retina.

corpus callosum { Figure }: large bundle of axons connecting the two cerebral hemispheres. It disseminates information from the cerebral cortex on one side of the brain to the same region on the other side; this is severed in split-brain subjects.

correlation: See coefficient of correlation.

correlation coefficient: statistical measure of the degree of relationship between two variables; usually varies from -1 (perfect negative) through zero (no correlation) to +1 (perfect positive); the "Pearson product moment coefficient" is the most commonly used.

correlational method: A research method used to determine whether some difference that is not under the researcher's control is associated, or correlated, with another difference of interest. See) coefficient of correlation.

cortex: outer or superficial part of an organ.

corticocortical connection: axon or axon bundle connecting one patch of cerebral cortex to another. Some remain local, within the superficial layers of cortex, while others go through the white matter to distant targets. Some go via the corpus callosum, to the other cerebral hemisphere.

corticotropin-release factor (CRF): A substance secreted by neurons in the hypothalamus in response to stress. It, in turn, is carried through a channel-like structure to the pituitary gland, causing ACTH (the body's major 'stress' hormone) to be released. See) adrenocorticotropic hormone.

cortisol: One of the steroid hormones produced by the adrenal glands. It has many effects on the body, including the formation of glucose, the reduction of inflammation, and the retention of water. Its level in the blood is used as a measure of stress. See) adrenal gland, adrenal-cortical system.

counseling psychologist: A trained psychologist, usually with a Ph.D. or Psy.D. degree, who deals with personal problems not classified as illness, such as academic, social, or vocational problems of students. He or she has skills similar to those of the clinical psychologist but usually works in a nonmedical setting. See) clinical psychologist, psychiatrist.

counterconditioning: In behavior therapy, the replacement of a particular response to a stimulus by the establishment of another (usually incompatible) response.

criterion: (a) A set of scores or other records against which the success of a predictive test is verified. (b) A standard selected as the goal to be achieved in a learning task; for example, the number of runs through a maze to be made without error as an indication that the maze has been mastered.

criterion problem: The difficulty that arises in validating a test or assessment instrument when there is no criterion behavior the investigator is willing to accept as the 'true' measure of the concept being evaluated. See) construct validity, validity.

criterion validity (empirical validity): The ability of a test or assessment instrument to predict the behavior it is designed to predict (syn. empirical validity). See) criterion, validity.

criterion-keyed method of test construction: Selecting items for a test or assessment instrument by comparing the responses of some criterion group (for example, paranoid individuals) with a control group and retaining only those that discriminate between the two groups.

critical period (sensitive period): Crucial time periods in a person's life during which specific events must occur for development to proceed normally.

cross-pressure: Conflicting social influences on an individual's beliefs, attitudes, or behaviors. Usually arises when a person identifies with more than one reference group.

cues to distance: See distance cues.

cultural psychology: An interdisciplinary approach involving psychologists, anthropologists, sociologists, and other social scientists that is concerned with how an individual's culture influences his or her mental representations and psychological processes.

cumulative curve: A graphic record of the responses emitted during an operant conditioning session. The slope of the cumulative curve indicates the rate of response.

DNA: See deoxyribonucleic acid.

DSM-IV: The fourth edition of the Diagnostic and Statistical Manual of the American Psychiatric Association, revised.

DZ twins: See dizygotic twins.

Down's syndrome (mongolism): A form of mental deficiency produced by a genetic abnormality (an extra chromosome on pair 21). Characteristics include a thick tongue, extra eyelid folds, and short, stubby fingers .

dark adaptation: The increased sensitivity to light when the subject has been continuously in the dark or under conditions of reduced illumination. See) light adaptation.

data-driven learning: A kind of associative learning in which people have no prior beliefs about the relation that has to be learned; learning is driven only by the input or data. See) belief-driven learning.

decibel (db): A measure of sound intensity. A change of 10 decibels corresponds to a change in sound power of 10 times; 20 decibels, a change of 100 times; and so forth.

deductive reasoning: Reasoning about arguments in which the conclusion cannot be false if the premises are true. See) inductive reasoning.

defense mechanisms: In Freud's psychoanalytic theory, the strategies used by the ego to ward off or to reduce anxiety. These consist of adjustments made unconsciously, either through action or the avoidance of action, to keep from recognizing personal motives that might threaten self-esteem or heighten anxiety. Repression, denial, and projection are examples.

degradation: The process in which enzymes in the membrane of a receiving neuron react with a neurotransmitter to break it up chemically and make it inactive; one method (in addition to reuptake) of terminating a neurotransmitter's action. See) neurotransmitter, reuptake.

deindividuation: A psychological state in which persons feel that they have lost their personal identities and have merged anonymously into a group. Hypothesized to be the basis for the impulsive, aggressive behaviors sometimes shown by mobs and crowds.

delayed conditioning: classical conditioning procedure in which the CS begins several seconds or more before the onset of the UCS and continues with it until the response occurs. See) trace conditioning.

delta waves: See electroencephalogram.

delusion: False beliefs characteristic of some forms of psychotic disorder. They often take the form of delusions of grandeur or delusions of persecution. See) hallucination, illusion, paranoid schizophrenia.

dendrite: specialized portion of the neuron that (together with the cell body) receives impulses from other neurons. See) axon.

denial: defense mechanism by which unacceptable impulses or ideas are not perceived or allowed into full awareness. See) defense mechanisms.

denotative meaning: primary meaning of a symbol, something specific to which the symbol refers or points. See) connotative meaning.

dependent variable: The variable whose measured changes are attributed to (or correspond to) changes in the independent variable. In psychological experiments, the dependent variable is often a response to a stimulus.

depolarization: change in the resting potential of the nerve cell membrane in the direction of the action potential; the inside of the membrane becomes more positive.

depressants: psychoactive drugs that tend to reduce arousal. Examples) alcohol, barbiturates, and opiates.

depression: A mood disorder characterized by sadness and dejection, decreased motivation and interest in life, negative thoughts (for example, feelings of helplessness, inadequacy, and low self-esteem) and such physical symptoms as sleep disturbances, loss of appetite, and fatigue. See) mood disorder.

depth perception: perception of the distance of an object from the observer. See) distance cues.

determinism: See psychological determinism.

developmental psychologist: A psychologist whose research interest lies in studying the changes that occur as a function of the growth and development of the organism, in particular the relationship between early and later behavior.

diathesis-stress model: See vulnerability-stress model.

dichromatism: color blindness in which either the red-green or the blue-yellow system is lacking. The red-green form is relatively common; the blue-yellow form is the rarest of all forms of color blindness. See) monochromatism, red-green color blindness, trichromatism.

difference reduction: problem-solving strategy in which one sets up subgoals that, when obtained, put one in a state closer to the goal. See) means-ends analysis, working backwards.

difference threshold: minimum difference between a pair of stimuli that can be perceived under experimental conditions. See) absolute threshold, just noticeable difference, threshold, Weber's law.

differential reinforcement: procedure in conditioning in which reinforcement is given only in the presence of a certain stimulus. The outcome of this procedure is a conditioned discrimination.

diffusion of responsibility: tendency for persons in a group situation to fail to take action (as in an emergency) because others are present, thus diffusing the responsibility for acting. A major factor in inhibiting bystanders from intervening in emergencies.

disaster syndrome: three-stage behavior pattern that is a common reaction to a traumatic event. The person is at first dazed and disoriented, then passive but able to respond to instructions, and finally anxious, apprehensive, and unable to concentrate.

discrimination: (a) In perception, the detection of differences between two stimuli. (b) In conditioning, the differential response to the positive (reinforced) stimulus and to the negative (nonreinforced) stimulus. See) generalization. (c) In social psychology, prejudicial treatment, as in racial discrimination. See) prejudice.

discriminative stimulus: stimulus that becomes an occasion for an operant response; for example, a knock that leads one to open the door. See) operant behavior.

dishabituation: return in strength of a response following habituation to a repeated stimulus. Indicates renewed attention on the part of the organism to a change in the stimulus situation. See) habituation.

displaced aggression: aggression against a person or object other than that which was (or is) the source of frustration. See) scapegoat.

displacement: a) defense mechanism whereby a motive that may not be directly expressed (such as sex or aggression) appears in a more acceptable form. See) defense mechanism. b) The principle of loss of items from short-term memory as too many new items are added. See) chunk, short-term memory.

display rules: a culture's rules for the types of emotions people should experience in certain situations, and the behaviors (including facial expressions) appropriate for each emotion.

dispositional attribution: attributing a person's actions to internal dispositions (attitudes, traits, motives), as opposed to situational factors. See) situational attribution.

dissociation: process whereby some ideas, feelings, or activities lose relationship to other aspects of consciousness and personality and operate automatically or independently.

dissociative identity disorder (formerly called multiple personality disorder): existence of two or more distinct identities or personalities within the same individual. Each identity has its own set of memories and characteristic behaviors. Typically, the attitudes and behaviors of the alternating personalities are markedly different. .

dissonance: Festinger's term for discomfort arising from a perceived inconsistency between one's attitudes and one's behavior.  See) cognitive dissonance.

distance cues (monocular cues): Vision) the monocular cues according to which the distance of objects is perceived, such as superposition of objects, perspective, light and shadow, and relative movement and the binocular cues used in stereoscopic vision. See) stereoscopic vision; Audition) corresponding cues governing perception of distance and direction, such as intensity and time differences of sound reaching the two ears.

dizygotic twins (DZ twins, fraternal twins): Twins developed from separate eggs. They are no more alike genetically than ordinary brothers and sisters and can be of the same or different sexes (syn. fraternal twin). See) monozygotic twins.

dominance: higher status position when social rank is organized according to a dominance-submission hierarchy; commonly found in human societies and in certain animal groups.

dominant gene: member of a gene pair which, if present, determines that the individual will show the trait controlled by the gene, regardless of whether the other member of the pair is the same or different (that is, recessive). See) recessive gene.

dopamine: neurotransmitter of the central nervous system believed to play a role in schizophrenia. It is synthesized from an amino acid by the action of certain body enzymes and, in turn, is converted into norepinephrine. See) neurotransmitter.

dopamine hypothesis: hypothesis that schizophrenia is related to an excess of the neurotransmitter dopamine; either schizophrenics produce too much dopamine or have an abnormally large number of dopamine receptors. See) dopamine, schizophrenia.

double blind: experimental design, often used in drug research, in which neither the investigator nor the patients know which subjects are in the treatment and which in the nontreatment condition until the experiment has been completed.

drive: internal cause for motivation, which arises independent of events outside the individual. Drive theories of motivation stress the role of physiological states and of homeostasis.

drive-reduction theory: theory that a motivated sequence of behavior can be best explained as moving from an aversive state of heightened tension (or drive) to a goal state in which the drive is reduced. The goal of the sequence, in other words, is drive reduction. See) drive, incentive theory, motive, need.

drug abuse: continued use of a drug despite serious consequences in the absence of signs of dependency (i.e., no symptoms of tolerance, withdrawal, or compulsive craving). See) drug dependence.

drug dependence: pattern of compulsive drug use usually characterized by tolerance (the need to consume more and more of the drug to achieve the same effect) and withdrawal (unpleasant reactions if use is discontinued). See) drug abuse.

dual-memory theory: distinguishes between a short-term memory of limited capacity and a virtually unlimited long-term memory. Information is encoded into long-term memory via short-term memory. See) long-term memory, short-term memory.

eardrum: membrane at the inner end of the auditory canal, leading to the middle ear. See) middle ear.

early selection: selective attention that occurs in the early stages of recognition, when the organism is constructing a description of the input and before the meaning of the input has been determined. See) late selection, selective attention.

educational psychologist: psychologist whose research interest lies in the application of psychological principles to the education of children and adults in schools. See) school psychologist.

ego: the rational part or controlling self in Freud's tripartite division of the personality. Operates on the reality principle, holding back the impulses of the id until they can be satisfied in socially approved ways. See reality principle, superego.

ego analyst: psychoanalyst, who focuses on the integrative, positive functions of the ego (for example, coping with the environment) rather than the functions of the id (for example, gratifying sexual impulses).

eidetic imagery: ability to retain visual images of pictures that are almost photographic in clarity and can be described in far greater detail than would be possible from memory alone. See) mental imagery.

elaboration: memory process wherein one expands verbal material so as to increase the number of ways to retrieve the material.

electroconvulsive therapy (ECT) (electroshock therapy): treatment for severe depression in which a mild electric current is applied to the brain, producing a seizure similar to an epileptic convulsion.

electroencephalogram (EEG): a record obtained by attaching electrodes to the scalp (or occasionally to the exposed brain). Among the brain waves observed are alpha waves (8-13 Hz), characteristic of relaxed wakefulness; delta waves (1-3 Hz), a slower wave of high amplitude that occurs during deep sleep; and theta waves (4-7 Hz), a pattern characteristic of the EEG of the hippocampus and indicative of behavioral arousal.

emotion: condition of the organism during affectively toned experience, whether mild or intense. See) affective experience.

emotion-focused coping: ways of reducing anxiety or stress that do not deal directly with the anxiety-producing situation; defense mechanisms are a form of emotion-focused coping. See) problem-focused coping.

empiricism: view that behavior is learned as a result of experience. See) nativism.

encoding: Memory) procedure for transforming something a person sees hears, thinks, or feels into a memory.

endocrine gland:

endocrine system: system of ductless glands that discharge their secretions (hormones) into the extracellular fluid around capillaries and hence into the bloodstream. The hormones secreted by the endocrine glands are important integrators of bodily functions.

endorphins: chemicals produced by the body that act like morphine to reduce pain.

engineering psychologist: psychologist specializing in the relationship between people and machines, seeking, for example, to design machines that minimize human error.

epinephrine (adrenalin): principal hormone secreted by the adrenal medulla in response to stressful situations. Its effects are similar to those brought about by stimulation of the sympathetic division of the autonomic nervous system (for example, arousal, increased heart rate and blood pressure). It is also an excitatory neurotransmitter in the central nervous system See) adrenal gland, norepinephrine.

episodic memory: memory that stores facts about personal episodes. The fact or episode is encoded with respect to the memorizer, and often with respect to the specific time and place as well. See) semantic memory.

equilibratory senses: give discrimination of the position of the body in space and of the movement of the body as a whole. See) kinesthesis, semicircular canals, vestibular sacs.

escape learning: learning to make a response in order to escape from an aversive event. See) avoidance learning.

estrogens: group of female sex hormones produced principally by the ovaries. They are responsible for the development of female body characteristics and hair distribution, and for preparing the reproductive system for pregnancy. See) androgens.

estrous cycle: recurring episodes of sexual receptivity that precede ovulation in most female mammals. They are characterized by rising and falling levels of estrogens and progesterone in the bloodstream.

ethology: study of animal behavior in the natural environment.

evocative interaction: interaction between individuals and their environments that arises because the behavior of different individuals evokes different responses from others. See) proactive interaction, reactive interaction.

evoked potential: electric discharge in some part of the nervous system produced by stimulation elsewhere. The measured potential is commonly based on response averaging by a computer.

evolutionary psychology: study of how psychological processes have evolved by means of natural selection; those behaviors that aided survival or increased the chance of reproduction have tended to persist through the course of evolutionary history.

excitatory synapse: synapse at which the neurotransmitter changes the membrane permeability of the receiving cell in the direction of depolarization. See) inhibitory synapse.

exemplar strategy: categorization strategy in which (a) old instances of a concept are memorized and (b) a new item is declared a member of that concept if it is sufficiently similar to the memorized instances.

expectation: anticipation or prediction of future events based on past experience and present stimuli.

experimental design: a plan for collecting and treating the data of a proposed experiment. The design is evolved after preliminary exploration, with the aims of economy, precision, and control, so that appropriate inferences and decisions can be made from the data.

experimental group: group of subjects given the treatment whose effect is under investigation. See) control group in an experimental design contrasting two groups.

experimental psychologist: uses experimental methods to study how people (and other animals) react to sensory stimuli, perceive the world, learn and remember, reason and respond emotionally.

explicit memory: underlies a conscious recollection of something in the past. See) implicit memory.

extinction: (a) The experimental procedure, following classical or operant conditioning, of presenting the conditioned stimulus without the usual reinforcement. (b) The reduction in response that results from this procedure. See) reinforcement.

extracellular fluid: fluid, including the blood, outside the cells; one of the critical variables monitored in the control of thirst.

extracellular reservoir: water outside the body's cells, including blood.

extrasensory perception (ESP): Response to external stimuli without any known sensory contact. See) clairvoyance, parapsychology, precognition, psi, psychokinesis, telepathy.

Fechner's law: that the perceived magnitude of a stimulus increases in proportion to the logarithm of its physical intensity.

Freudian slip: psychoanalytic theory) mistake or substitution of words in speaking or writing that is contrary to the speaker's conscious intention and presumably expresses wishes or thoughts repressed to the unconscious.

Freud's psychosexual stages:

facial feedback hypothesis: that the subjective experience of an emotion is determined by feedback from the physiological arousal caused by engaging in specific facial expressions.

factor analysis: statistical method that enables the investigator to compute the minimum number of determiners (factors) required to account for the intercorrelations in interpreting scores from batteries of tests or in test construction.

family therapy: psychotherapy with the family members as a group rather than treatment of the patient alone. See) group therapy.

feature detector: general term for any perceptual mechanism that detects distinctive features in a complex display (eg, a line (edge) or angle in vision); postulated to be the building blocks for recognizing more complex forms.

fetal alcohol syndrome: abnormal development of the fetus and infant caused by maternal alcohol consumption during pregnancy, to include retarded growth, small head circumference, a flat nasal bridge, a small midface, shortened eyelids, and mental retardation.

fight-or-flight response: pattern of bodily responses that prepares the organism for an emergency. Most of these physiological changes result from activation of the sympathetic system and the adrenalcortical system. Includes increases in pupil size, heart rate, blood pressure, respiration, muscle tension, and the secretion of epinephrine, norepinephrine, ACTH and other hormones; decreases in saliva, mucous, digestive activity, and the size of blood vessels.

figure-ground organization: common perception of a pattern as foreground against a background, at times even when the stimuli are ambiguous and the foreground-background relationships are reversible.

file-drawer problem: arises because studies that fail to obtain positive results are less likely to be published than studies that do obtain positive results, which may cause a database of known studies to be biased toward confirming studies.

fixation: Freud's psychoanalytic theory) arrested development through failure to pass beyond one of the earlier stages of psychosexual development or to change the objects of attachment (such as fixation at the oral stage or fixation on the mother).

flashbulb memory: vivid and relatively permanent record of the circumstances in which one learns about an emotionally charged, significant event.

flooding: procedure in behavior therapy whereby a fearful person exposes himself or herself to what is frightening, in reality or in imagination, for extended periods of time without opportunity to escape. See) behavior therapy.

formal operational stage: Piaget's fourth stage of cognitive development (age 11 and up) in which the child becomes able to use abstract rules.

fovea: Eye) small area in the central part of the eye's retina, packed with cones; the most sensitive part of the retina for detail vision and color vision in daylight.

free association: (a) form of word-association experiment in which the subject gives any word he or she thinks of in response to the stimulus word. (b) In psychoanalysis, the effort to report without modification everything that comes into awareness.

free recall: memory task in which a subject is given a list of items (usually one at a time) and is later asked to recall them in any order.

frequency: Audition)

frontal lobe { Figure }: portion of each cerebral hemisphere, in front of the central fissure. See) occipital lobe, parietal lobe, temporal lobe.

frustration: as an event) the thwarting circumstances that block or interfere with goal-directed activity. As a state) the annoyance, confusion, or anger engendered by being thwarted, disappointed, defeated.

frustration-aggression hypothesis: that frustration (thwarting a person's goal-directed efforts) induces an aggressive drive, which, in turn, motivates aggressive behavior.

fundamental: the frequency being played in a musical note.

fundamental attribution error: The tendency to underestimate situational influences on behavior and assume that some personal characteristic of the individual is responsible; the bias toward dispositional rather than situational attributions. See) attribution, dispositional attribution, situational attribution.

fuzzy concept: A concept in which one primarily relies on prototype properties in determining membership, and hence cannot always be sure of one's decisions. See) prototype.

galvanic skin response (GSR): Changes in electrical conductivity of, or activity in, the skin, detected by a sensitive galvanometer. The reactions are commonly used as an emotional indicator.

gamma-aminobutyric acid (GABA): An important inhibitory neurotransmitter.

ganglia:

gate control theory of pain: that the sensation of pain requires not only that pain receptors be activated, but also that a neural gate in the spinal cord allow these signals to continue to the brain. Pressure stimulation tends to close the gate; this is why rubbing a hurt area can relieve pain. Attitudes, suggestions, and drugs may act to close the gate.

gender constancy: a child's realization that sex does not change with age or appearance (e.g., wearing opposite-sex clothes). A direct analogue to Piaget's concept of conservation in the child's understanding of the physical world.

gender identity: sense of self as either male or female.

gender schema: mental structure that organizes the perceptual and conceptual world into gender categories (male-female, masculine-feminine). Gender schema theory holds that society produces gender identity and sex typing by teaching individuals to use the gender schema as a set of 'lenses' through which to view reality. See) gender identity, schema, sex typing.

gene: basic unit of hereditary transmission, localized within the chromosomes. Each chromosome contains many genes. Genes are typically in pairs, one member of the pair being found in the chromosome from the father, the other in the corresponding chromosome from the mother. See) dominant gene, recessive gene.

General Problem Solver (GPS): computer program to simulate human problem solving by setting up subgoals and reducing the discrepancies to each subsequent subgoal. See) simulation.

generalization: concept formation) problem solving, and transfer of learning, the detection by the learner of a characteristic or principle common to a class of objects, events, or problems; conditioning) the principle that once a conditioned response has been established to a given stimulus, similar stimuli will also evoke that response. See) discrimination.

generalized anxiety disorder: characterized by persistent tension and apprehension, and may be accompanied by physical symptoms such as rapid heart rate, fatigue, disturbed sleep, and dizziness. See) anxiety disorders.

genetics: branch of biology concerned with heredity and the means by which hereditary characteristics are transmitted.

genital stage: Freud's psychoanalytic theory) final stage of psychosexual development, beginning at puberty and culminating in mature adult sexuality. See) psychosexual development.

genotype: genetics) characteristics that an individual has inherited and will transmit to his or her descendants, whether or not the individual manifests these characteristics. See) phenotype.

geon: perception) geometric forms (such as cylinders, cones, blocks, and wedges) that comprise the features of objects. Recognition of an object is good to the extent that the geons of the object can be recovered.

Gestalt psychology: system of psychological theory concerned primarily with perception that emphasizes pattern, organization, wholes, and field properties.

glia cells: supporting cells (not neurons) composing a substantial portion of brain tissue; recent speculation suggests that they may play a role in neural conduction.

glutamate: an amino acid that serves as an important excitatory neurotransmitter.

gonads: sexual organs that secrete sexual hormones and that manufacture reproductive cells. Female gonads, called ovaries, secrete estrogen and produce egg cells. Male gonads, called testes, secrete androgen (especially testosterone) and produce sperm cells.

graded potentials: potential changes of varying size induced in a neuron's dendrites or cell body by stimulation from synapses from other neurons. When the graded potentials reach a threshold of depolarization, an action potential occurs.

group polarization: tendency of groups to arrive at decisions that are in the same direction but are more extreme than the mean of the pre-discussion decisions of the individuals in the group.

group therapy: discussion or other group activity with a therapeutic purpose participated in by more than one client or patient at a time. See) psychotherapy.

groupthink: tendency of members of some decision-making groups to suppress their own dissenting opinions in the interests of group consensus, thereby producing an inadequate decision-making process and poor decisions.

gustation: sense of taste.

habit: a learned stimulus-response sequence. See) conditioned response.

habituation: reduction in the strength of a response to a repeated stimulus. In general, almost any stimulus will produce habituation; for example, a pure tone sounded for a half-hour may decrease as much as 20 db in perceived loudness. See) dishabituation.

habituation method: technique used to study perception in infants. It is based on the fact that while infants look directly at novel objects they soon tire of doing so (habituation). Hence one can determine the degree to which an infant perceives an object as novel by measuring the time spent looking at it.

hair cells: audition) hairlike receptors in the cochlea that bend due to vibration of the basilar membrane and then send electrical impulses to the brain.

hallucination: sense experience in the absence of appropriate external stimuli; a misinterpretation of imaginary experiences as actual perceptions. See) delusion, illusion, schizophrenia.

hallucinogens (psychedelic drugs): drugs whose main effect is to change perceptual experience and 'expand consciousness.' LSD and marijuana are examples.

halo effect: tendency to bias our perception of another person in the direction of one particular characteristic that we like or dislike.

heritability: proportion of the total variability of a trait in a given population that is attributable to genetic differences among individuals within the population.

hermaphrodite: individual born with genitals that are ambiguous in appearance or that are in conflict with the internal sex glands. See) transsexual.

heroin: extremely addictive central nervous system depressant derived from opium. See) opiates.

hertz (Hz): unit used to measure the frequency of a sound wave, specifically the number of cycles per second.

heterosexual: sexual attraction primarily to members of the opposite sex.

heuristic: problem solving strategy that can be applied to a variety of problems and that usually, but not always, yields a correct solution.

hierarchies of concepts: relationships among individual concepts.

hierarchy of needs: Maslow's classification of needs and motives, ascending from basic biological needs to a peak of self-actualization, supposedly the highest human motive.

hippocampus: brain structure located below the cerebral cortex that is involved in the consolidation of new memories; its role seems to be that of a cross-referencing system, linking together aspects of a particular memory that are stored in separate parts of the brain.

home sign: system of gestures used by deaf children that initially functions as a kind of simple pantomime but eventually takes on the properties of a language.

homeostasis: motivational control system based on negative feedback, which maintains a constant physiological or psychological state. Homeostatic systems keep body temperature, water balance, energy balance, etc., close to critical goal values. When the state deviates from the goal value, the homeostatic system activates a response that will correct the deviation.

hormone: chemical messenger produced by an organ in one part of the body and transported through the bloodstream to other parts of the body where it has a specific effect on cells that recognize its message. See) endocrine system.

hue: lack of gray; dimension of color from which the major color names are derived (red, yellow, green, and so on), corresponding to wavelength of light. See) saturation.

humanistic psychology: emphasizes uniqueness of human beings and is concerned with subjective experience and human values. See) phenomenology.

humanistic therapies: general term for approaches to psychotherapy that emphasize subjective experiences, free will, and the ability to solve one's own problems. Client-centered therapy and Gestalt therapy are examples.

hunger drive: drive based on food deprivation. See) specific hunger.

hypercomplex cell: cell in the visual cortex that responds to a particular orientation and length. See) complex cell, feature detector, simple cell.

hyperphagia: Pathological overeating. See) aphagia.

hypnosis: responsive state achieved following a hypnotic induction or its equivalent. In this state, one person (the subject) responds to suggestions offered by another person (the hypnotist) and experiences alterations in perception, memory, and voluntary action.

hypnotic induction: procedure used in establishing hypnosis in a responsive person, usually involving relaxation and stimulated imagination. See) hypnosis.

hypnotic trance: dreamlike state of heightened suggestibility induced in a subject by a hypnotist. See) posthypnotic suggestion.

hypothalamus: small but important structure located just above the brain stem and just below the thalamus. Considered a part of the central core of the brain, it includes centers that govern motivated behavior such as eating, drinking, sex, and emotions; it also regulates endocrine activity and maintains body homeostatis. See) lateral hypothalamus, ventromedial hypothalamus.

hypothesis testing: gathering information and testing alternative explanations of some phenomenon.

hypothetical construct: one form of inferred intermediate mechanism. The construct is conceived of as having properties of its own, other than those specifically required for the explanation; for example, drive that is inferred from the behavior of a deprived organism and is used in the explanation of later behavior.

id: Freud's tripartite division of the personality) the most primitive part, consisting of the basic biological impulses (or drives). The source of psychic energy or libido. Operates on the pleasure principle, endeavoring to obtain pleasure and to avoid pain, regardless of external circumstances. See) ego, libido, pleasure principle, superego.

identification: changing one's beliefs, attitudes, or behaviors in order to be like an admired reference group. See) compliance, internalization.

identification figures: adult models (especially parents) copied, partly unconsciously, by the child. See) identification.

identity crisis: Erikson's theory of psychosocial development) period of self-doubt and active questioning about one's definition of self ('Who am I?' 'Where am I going?') which typically takes place during adolescence. See) identity status, psychosocial stages.

identity status: An individual's position on Erikson's identity-formation continuum, which includes identity achievement, foreclosure, moratorium, and identity diffusion (or confusion). See) identity crisis.

illusion: perception) misinterpretation of the relationships among presented stimuli so that what is perceived does not correspond to physical reality; especially, but not exclusively, an optical or visual illusion. See) delusion, hallucination.

imitation: behavior that modeled on or copying that of another. See) identification.

impossible figures: figure in which recognition is normal when attending to each part, but the parts do not fuse into a single coherent picture.

impression formation:

imprinting: type of early learning in which a newborn forms an attachment with some kind of model (normally, a parent).

incentive: external event or stimulus that is the target of a motivation, and that can serve as a reward. Incentive theories of motivation stress the role of external targets in eliciting and satisfying motivational states.

incentive theory: theory of motivation that emphasizes the importance of negative and positive incentives in determining behavior; internal drives are not the sole instigators of activity. See) drive-reduction theory.

independent variable: variable under experimental control with which the changes studied in the experiment are correlated.  See) dependent variable

individual differences: relatively persistent dissimilarities in structure of behavior among persons or members of the same species.

induced motion: perception of motion caused when a larger object surrounding a smaller object moves; the smaller object may appear to be the one that is moving even if it is stationary. See) stroboscopic motion.

inductive reasoning: reasoning about arguments in which it is improbable that the conclusion is false if the premises are true. See) deductive reasoning.

industrial psychologist: is concerned with such problems as selecting people most suitable for particular jobs, developing job training programs, and figuring out the determinants of consumer behavior.

infancy: period of helplessness and dependency in humans and other organisms; in humans, roughly the first 2 years.

inhibitory synapse: synapse at which the neurotransmitter changes the membrane permeability of the receiving cell in the direction of the resting potential; in other words, keeps it from firing. See) excitatory synapse.

inhibitory transmitter:

inner ear: internal portion of the ear containing, in addition to the cochlea, the vestibular sacs and the semicircular canals.

insight: problem-solving experiments) perception of relationships leading to solution. Such a solution can be repeated promptly when the problem is again confronted; psychotherapy) discovery by the individuals of dynamic connections between earlier and later events so that they come to recognize the roots of their conflicts.

insomnia: dissatisfaction with the amount or quality of one's sleep. The diagnosis is subjective because many people who complain of insomnia are found to have normal sleep when studied in the laboratory, whereas others who do not complain of insomnia are found to have detectable sleep disturbances. See) apnea.

instinct (species-specific behavior): innately determined behavior that is specific to a certain species and appears in the same form in all members of the species.

insulin: hormone secreted by the pancreas. See) hormone.

intellectualization: defense mechanism whereby a person tries to gain detachment from an emotionally threatening situation by dealing with it in abstract, intellectual terms. See) defense mechanisms.

intelligence: (a) That which a properly standardized intelligence test measures. (b) The ability to learn from experience, think in abstract terms, and deal effectively with one's environment. See) intelligence quotient, mental age.

intelligence quotient (IQ): scale unit used in reporting intelligence test scores, based on the ratio between mental age and chronological age. The decimal point is omitted so that the average IQ for children of any one chronological age is set at 100. See) deviation IQ.

interactionism: personality-development theory) framework in which personality is seen as resulting from the interaction between the child's genotype (inherited characteristics) and the environment in which he or she is raised; personality theory) framework in which behavior is seen as resulting from the interaction between consistent personality dispositions or traits and the situations in which people find themselves. See) evocative interaction, proactive interaction, reactive interaction.

interaural intensity difference: difference in intensity of sounds reaching the two ears; it aids in the localization of sounds at high frequencies. See) interaural time difference.

interaural time difference: difference in time between the arrival of sound waves at the two ears; it aids in the localization of sounds at low frequencies. See) interaural intensity.

interference: factor that can impair retrieval from long-term memory. It arises when different items are associated with the same retrieval cue; attempted retrieval of one of these items can be blocked by the inadvertent retrieval of the other item.

interjudge reliability (inferater agreement) (interrater agreement): consistency achieved by two or more observers when assessing or rating some behavior (for example, in rating the aggressiveness of nursery-school children). See) reliability.

internal consistency: form of test reliability. Specifically, the homogeneity of a set of items on a test, the degree to which they are all measuring the same variable. See) reliability.

internalization: changing one's beliefs, attitudes, and behaviors because one genuinely believes in them. Incorporating them into one's own value system. See) compliance, identification.

interneurons: neurons in the central nervous system that receive messages from sensory neurons and send them to other interneurons or to motor neurons.

interpretation: psychoanalysis) the analyst's calling attention to the patient's resistances in order to facilitate the flow of associations; also the explanation of symbols, as in dream interpretation.

interval schedules: operant conditioning) reinforcement schedules in which reinforcement occurs only after a certain time interval has elapsed. On a fixed interval (FI) schedule, the organism is reinforced for its first response only after a certain amount of time has passed since its last response. On a variable interval (VI) schedule, reinforcement still depends on time since last response, but the interval's duration varies unpredictably. See) ratio schedules.

intervening variable: process inferred to occur between stimulus and response, thus accounting for one response rather than another to the same stimulus. The intervening variable may be inferred without further specification, or it may be given concrete properties and become an object of investigation.

interview: conversation between an investigator (the interviewer) and a subject (the respondent) used for gathering pertinent data for the subject's benefit (as in the psychotherapeutic interview) or for information-gathering (as in a sample survey).

intracellular fluid: water contained within the body's cells; one of the critical variables monitored in the control of thirst.

intracellular reservoir: water inside the body's cells.

introversion-extraversion: personality dimension first identified by Carl Jung that refers to the degree to which a person's basic orientation is turned inward toward the self or outward toward the external world. At the introversion end are shy individuals who tend to withdraw into themselves; at the extraversion end are sociable individuals who prefer to be with others.

ion channel: specialized protein molecule that permits specific ions to enter or leave cells. Some ion channels open or close in response to appropriate neurotransmitter molecules; others open or close in response to voltage changes across the cell membrane. This process regulates depolarization and the firing of nerve impulses.

ion pump: protein molecule that helps to maintain an uneven distribution of electrically charged ions across the cell membrane of a neuron by pumping them into or out of the cell. Ion pumps work with ion channels to regulate depolarization and firing of nerve impulses. See) depolarization.

Jacobson's progressive relaxation method:

James-Lange theory: classical theory of emotion, named for the two men who independently proposed it. The theory states that the stimulus first leads to bodily responses, and then the awareness of these responses constitutes the experience of emotion. See) Cannon-Bard theory, cognitive-appraisal theory.

just noticeable difference (jnd): barely perceptible physical change in a stimulus; a measure of the difference threshold. The term is used also as a unit for scaling the steps of sensation corresponding to increases in the magnitude of stimulation. See) Weber's law.

key-word method: technique for learning vocabulary of a foreign language via an intermediate key word related to the sound of the foreign word and the meaning of the English equivalent. See) mnemonics.

kinesthesis: muscle, tendon, and joint senses, yielding discrimination of position and movement of parts of the body. See) equilibratory senses.

late selection: selective attention that occurs in the later stages of recognition, after the organism has determined the meaning of the input. See) early selection.

latency: temporal measure of response, referring to the time delay between the occurrence of the stimulus and the onset of the response. See) psychosexual development.

latency period: Freud's psychoanalytic theory) period in middle childhood, roughly the years 6-12, when both sexual and aggressive impulses are said to be in a quiescent state.

latent content: underlying significance of a dream (such as the motives of wishes being expressed by it) as interpreted from the manifest content.

lateral fissure (fissure of Sylvius): deep fissure at the side of each cerebral hemisphere, below which lies the temporal lobe.

lateral hypothalamus (LH): area of the hypothalamus important to the regulation of food intake. Electrical stimulation of this area will make an experimental animal start to eat; destruction of brain tissue here causes an animal to stop eating. See) ventromedial hypothalamus.

lateral ventricle:

law of effect: phenomenon that any behavior that is followed by reinforcement is strengthened; from the infinite pool of possible responses, those that lead to reinforcement are repeated, whereas those that do not are extinguished.

learned helplessness: condition of apathy or helplessness created experimentally by subjecting an organism to unavoidable trauma (such as shock, heat, or cold). Being unable to avoid or escape an aversive situation produces a feeling of helplessness that generalizes to subsequent situations.

learning: relatively permanent change in behavior that occurs as the result of practice. Behavior changes due to maturation or temporary conditions of the organism (such as fatigue, the influence of drugs, adaptation) are not included.

left hemisphere (major hemisphere): left cerebral hemisphere. Controls the right side of the body and, for most people, speech and other logical, sequential activities. See) corpus callosum, right hemisphere, split-brain subject.

lens: part of the eye that helps focus light rays on a single point of the retina. See) cornea, pupil, retina.

libido: (Latin=>lust). Freud's psychoanalytic theory) the psychic energy of the id.

light adaptation: the decreased sensitivity of the eye to light when the subject has been continuously exposed to high levels of illumination. See) dark adaptation.

lightness: sensory psychology) the degree to which a light appears white (which is different from brightness, in that a dimly lit object can still appear white).

limbic system: set of structures in and around the midbrain, forming a functional unit regulating motivational and emotional types of behavior, such as waking and sleeping, excitement and quiescence, feeding, and mating.

linear perspective: perspective) a monocular cue for depth. When parallel lines appear to converge, they are perceived as vanishing in the distance. See) relative height, relative size, superposition.

linguistic relativity hypothesis: that one's thought processes, the way one perceives the world, are determined by one's language.

lithium carbonate: chemical compound based on lithium (an element related to sodium) that has been successful in treating bipolar disorders.

localized functions: behavior controlled by known areas of the brain; for example, vision is localized in the occipital lobes.

location constancy: tendency to perceive the place at which a resting object is located as remaining the same even though the relationship to the observer has changed. See) perceptual constancy.

long-term memory (LTM): relatively permanent component of the memory system, as opposed to short-term memory.

long-term potentiation: phenomenon concerning the neural bases of learning. Once stimulated, neurons will show an increase in their rate of activity when subsequently stimulated (at least up to a period of months).

longitudinal study: research method that studies an individual through time, taking measurements at periodic intervals. See) case history.

loudness: intensity dimension of hearing correlated with the amplitude of the sound waves that constitute the stimulus. Greater amplitudes yield greater loudnesses. See) pitch, timbre.

lucid dream: events seem so normal (lacking the bizarre and illogical character of most dreams) that the dreamer believes he or she is awake and conscious.

lunch-line effect: an example of peripheral attention. Even though you may be absorbed in conversation in a room full of people, the sound of your name in another conversation will usually attract your attention; this phenomenon suggests a nonconscious monitoring of that conversation.

lymphocyte:

lysergic acid diethylamide (LSD): powerful psychoactive drug capable of producing extreme alterations in consciousness, hallucinations, distortions in perception, and unpredictable mood swings.

magnetic resonance imaging (MRI): computer-based scanning procedure that uses strong magnetic fields and radio-frequency pulses to generate a picture of a cross section of the brain or body. Provides greater precision than the CT scanner.

mania:

manifest content: remembered content of a dream, the characters, and their actions, as distinguished from the inferred latent content.

marital therapy (couples therapy): psychotherapy with both members of a couple aimed at resolving problems in their relationship.

masochism: pathological desire to inflict pain on oneself or to suffer pain at the hands of others. See) sadism.

maternal drive: drive, particularly in animals, induced in the female through bearing and nursing young, leading to nestbuilding, retrieving, and other forms of care. See) drive.

maturation: growth processes in the individual that result in orderly changes in behavior, whose timing and patterning are relatively independent of exercise or experience though they may require a normal environment.

maze: device use in the study of animal and human learning, consisting of a correct path and blind alleys.

mean: arithmetical average; the sum of all scores divided by their number. See) measure of central tendency.

means-ends analysis: problem-solving strategy in which one compares one's current state to the goal state in order to find the most important difference between them; eliminating this difference then becomes the main subgoal. See) difference reduction, working backwards.

measure of central tendency: a value representative of a frequency distribution, around which other values are dispersed; for example, the mean, the median, or mode of a distribution of scores.

measure of variation: measure of the dispersion or spread of scores in a frequency distribution, such as the range or the standard deviation.

measurement: assigning numbers to different levels, amounts, or sizes of a variable.

medial-temporal-lobe amnesia: form of amnesia or memory loss that results from damage to the middle of the temporal lobe of the brain.

median: score of the middle case when cases are arranged in order of size of score. See) measure of central tendency.

meditation (mantra): an altered state of consciousness in which the individual is extremely relaxed and feels divorced from the outside world; the individual loses self-awareness and gains a sense of being involved in a wider consciousness. This meditative state is achieved by performing certain rituals, including regulating breathing, sharply restricting one's field of attention, and assuming yogic body positions. A commercialized form of meditation has been widely promoted under the name of transcendental meditation or TM.

medulla: lowest section of the brainstem, a slight enlargement of the spinal cord as it enters the skull; the point at which the major nerve tracts cross over so that the right cerebral hemisphere controls the left side of the body, and the left cerebral hemisphere controls the right side.

memory decay: a major cause of forgetting in short-term memory in which information simply fades with time.

memory span: number of items (digits, letters, words) that can be reproduced in order after a single presentation. See) chunk, short-term memory.

memory trace: inferred change in the nervous system that persists between the time something is learned and the time it is recalled.

menarche: first menstrual period, indicative of sexual maturation in a girl.

mental age (MA): scale unit proposed by Binet for use in intelligence testing. If an intelligence test is properly standardized, a representative group of children of age 6 should earn an average mental age of 6, those of age 7, a mental age of 7, and so on. A child whose MA is above his or her chronological age (CA) is advanced; one whose MA lags behind is retarded. See) intelligence quotient.

mental imagery: mental representations that are picture-like. Not the same as eidetic_imagery.

mental model: concrete mental representation of a problem situation that may be useful in solving the problem.

mental practice: imagined rehearsal of a perceptual-motor skill in the absence of gross body movements. For example, picturing yourself serving a tennis ball and making mental corrections when the movement seems faulty, without actually moving your arm.

mental retardation: subnormal intellectual functioning with impairment in social adjustment.

mental rotation: notion that a mental image of an object can be rotated in the mind in fashion analogous to rotating the real object.

mesolimbic dopamine system: set of neurons in the upper brainstem that is crucial to incentive motivation for food and other rewards. The neurons begin in the midbrain and project their axons upward to limbic structures in the forebrain, where they release dopamine as a neurotransmitter.

meta-analysis: statistical technique that treats the accumulated studies of a particular phenomenon as a single grand experiment and each study as a single observation.

method of constant stimuli: psychophysical method for determining sensory thresholds. Stimuli with magnitudes varying around the threshold are presented to a subject many times to see what percentage of the time the subject detects them.

method of loci: an aid to serial memory. Verbal material is transformed into mental images, which are then located at successive positions along a visualized route, such as an imaged walk through the house or down a familiar street.

middle ear: part of the ear that transmits sound waves from the eardrum to the oval window of the inner ear by means of three tiny connecting bones (malleus, incus, and stapes). See) cochlea, inner ear.

minor hemisphere: See right hemisphere.

mnemonics: system for improving memory often involving a set of symbols that can substitute for the material to be remembered; for example, in attempting to remember a number sequence, one may translate the sequence into letters of the alphabet that in turn approximate words that are easily remembered.

mode: the most frequent score in a distribution, or the class interval in which the greatest number or cases fall. See) measure of central tendency.

model: behavior therapy) one who models or performs behaviors that the therapist wishes the patient to imitate.

modeling: social learning theory) process by which a person learns social and cognitive behaviors by observing and imitating others.

monocular: see monocular cuew

monoamine oxidase (MAO): one of the enzymes responsible for the breakdown of a group of neurotransmitters called biogenic amines (norepinephrine, dopamine, and serotonin are examples); believed to be important in the regulation of emotion. Drugs that inhibit the action of this enzyme (monamine oxidase (MAO) inhibitors) are used in treating depression. See) antidepressant.

monoamine oxidase inhibitor (MAOI): class of drugs used to treat depression; the drug inhibits the action of an enzyme (monoamine oxidase) that breaks down certain neurotransmitters (such as dopamine, norepinephrine, and serotonin), thereby prolonging the action of these neurotransmitters. See) antidepressant.

monochromatism: total color blindness, the visual system being achromatic. A rare disorder. See) dichromatism, trichromatism.

monozygotic twins (MZ twins) (identical twins): twins developed from a single egg. They are always of the same sex and commonly much alike in appearance, although some characteristics may be in mirror image; for example one right-handed, the other left-handed. See) dizygotic twins.

mood disorder: mental disorder characterized by disturbances of mood. Depression, mania (exaggerated excitement), and bipolar disorders in which the individual experiences both extremes of mood are examples. See) depression.

moon illusion: perceptual illusion that makes the moon appear as much as 50 percent larger when it is near the horizon than when it is at its zenith, even though at both locations the moon produces the same retinal image.

moral realism: Piaget's theory of cognitive development) preoperational child's treatment of social rules as absolute and unchangeable. Also see preoperational stage.

morpheme: smallest meaningful unit in the structure of a language, whether a word, base, or affix; such as man, strange, ing, pro. See) phoneme.

morphine:

motion aftereffect: illusion of movement in a static object that occurs after viewing motion for an extended period of time; the aftereffect occurs in the opposite direction of the viewed motion.

motion parallax: monocular cue to depth perception. When you are moving rapidly, nearby objects appear to move more quickly in the opposite direction than distant objects do. This difference in apparent speed provides a cue to the respective depths of the objects.

motivation: factors that energize behavior and give it direction.

motive: any condition of the organism that affects its readiness to start on or continue in a sequence of behavior.

motor neuron (efferent neuron): neuron, or nerve cell, that conveys messages from the brain or spinal cord to the muscles and glands. See) sensory neuron.

multivariate experiment: type of experiment that involves the simultaneous manipulation of several independent variables.

myelin sheath: fuzzy sheath surrounding certain nerve fibers known as myelinated fibers. Impulses travel faster and with less energy expenditure in myelinated fibers than in unmyelinated fibers.

N-methyl D-aspartate receptor (NMDA receptor): receptor molecule that requires two successive chemical signals to activate it; the first signal makes the receptor more responsive (a phenomenon known as long-term potentiation) so that when a second chemical signal occurs (the neurotransmitter glutanate), the receptor is activated. NMDA receptors are particularly dense in the hippocampus and may explain how memories are stored by linking neurons to form new neural circuits. See) hippocampus, neuroreceptor molecule.

nanometer (nm): billionth of a meter. Wavelengths of light is measured in nanometers.

narcissism: self-love; Freud's psychoanalytic theory) normal expression of pregenital development.

narcolepsy: sleep disturbance characterized by an uncontrollable tendency to fall asleep for brief periods at unexpected times.

narcotics: See opiates.

nativism: view that behavior is innately determined. See) empiricism.

nature-nurture issue: problem of determining the relative importance of heredity (nature) and the result of upbringing in a particular environment (nurture) on mature ability.

need: physical state involving any lack or deficit within the organism. See) drive, motive.

negative incentive: object or circumstance away from which behavior is directed when the object or circumstance is perceived or anticipated. See) positive incentive.

negative reinforcement: reinforcing a response by the removal of an aversive stimulus. See) negative reinforcer.

negative reinforcer: any stimulus that, when removed following a response, increases the probability of the response. Loud noises, electric shock, and extreme heat or cold classify as negative reinforcers. See) punishment.

negative symptoms: in schizophrenia, behavioral deficits such as flattened affect, apathy, and poverty of speech. Presumed to result from abnormalities in brain structure. See) positive symptoms.

nerve: bundle of elongated axons belonging to hundreds or thousands of neurons, possibly both afferent and efferent neurons. Connects portions of the nervous system to other portions and to receptors and effectors.

neural pathways:

neuro-endocrine system:

neuroimaging: Newly developed techniques that can create visual images of a brain in action, with an indication of which regions of the brain show the most neural activity during a particular task. One of the most widely used neuroimaging techniques is positron emission tomography (PET).

neuron (nerve cell): the basic unit of a synaptic nervous system.

neuroreceptor molecule: protein molecule in a cell membrane that is sensitive to a particular chemical, such as a neurotransmitter. When the appropriate chemical activates a neuroreceptor molecule, changes occur in the cell membrane that either increase or decrease its permeability. Some neurotransmitters have an excitatory effect when locked to their neuroreceptors; others have an inhibitory effect.

neuroscience:

neurosis (pl. neuroses): mental disorder in which the individual is unable to cope with anxieties and conflicts and develops symptoms that he or she finds distressing, such as obsessions, compulsions, phobias, or anxiety attacks. Freud's psychoanalytic theory)neurosis results from the use of defense mechanisms to ward off anxiety caused by unconscious conflicts. No longer a diagnostic category of DSM-IV. See) anxiety disorders, obsessive-compulsive disorder.

neurotic anxiety: fear that is out of proportion to the actual danger posed (such as stage fright). See) anxiety, objective anxiety.

neuroticism: Eysenck's factor-analytic theory of personality) the emotional instability-stability dimension. Moody, anxious, and maladjusted individuals are at the neurotic or unstable end; calm, well-adjusted individuals are at the other. See) introversion-extraversion.

neurotransmitter: chemical involved in the transmission of nerve impulses across the synapse from one neuron to another. Usually released from small vesicles in the synaptic terminals of the axon in response to the action potential; diffuses across synapse to influence electrical activity in another neuron. See) dopamine, epinephrine, norepinephrine, serotonin.

nonconscious processes: a considerable body of research indicates that we register and evaluate stimuli that we are not consciously aware of. The stimuli are said to influence us unconsciously or to operate at an unconscious (or subconscious) level of awareness. See) consciousness.

norepinephrine (noradrenalin): one of the hormones secreted by the adrenal medulla; its action in emotional excitement is similar in some, but not all, respects to that of epinephrine. It is also a neurotransmitter of the central nervous system. Norepinephrine synapses can be either excitatory or inhibitory. Believed to play a role in depression and bipolar disorders. See) adrenal gland.

normal curve: plotted form of the normal distribution.

normal distribution: standard symmetrical bell-shaped frequency distribution, whose properties are commonly used in making statistical inferences from measures derived from samples; symmetrical, bell-shaped or Gaussian distribution. Data should be collected in an ordinal and preferably continuous scale to be tested for normality. Skewness and kurtosis are the central measures of normality. See) normal curve.

nuclei (sing. nucleus): collection of nerve cell bodies grouped in the brain or spinal cord. See) ganglia.

null hypothesis: a statistical hypothesis that any difference observed among treatment conditions occurs by chance and does not reflect a true difference. Rejection of the null hypothesis means that we believe the treatment conditions are actually having an effect.

Oedipal conflict: Freud's psychoanalytic theory) conflict that arises during the phallic stage of psychosexual development in which the individual is sexually attracted to the parent of the opposite sex and perceives the same-sex parent as a rival. See) phallic stage, psychosexual development.

obesity: condition of being 30 percent or more in excess of one's appropriate body weight.

object permanence: Piaget's term for the child's realization that an object continues to exist even though it is hidden from view. See) sensorimotor stage.

object relations theory: outgrowth of psychoanalytic theory that deals with the person's attachments to others over the course of development. Emphasizes ego functioning more than did classical psychoanalytic theory.

object size: size of an object as determined from measurement at its surface. When size constancy holds, the observer perceives a distant object as being near its object size. See) retinal size.

objective anxiety: Fear that is proportionate to the danger posed.

observational method: studying events as they occur in nature, without experimental control of variables; for instance, studying the nest-building of birds, or observing children's behavior in a play situation. See) experimental method.

obsession: persistent, unwelcome, intrusive thought, often suggesting an aggressive or sexual act. See) compulsion, obsessive-compulsive disorder.

obsessive-compulsive disorder: anxiety disorder taking one of three forms: (a) recurrent thoughts, often disturbing and unwelcome (obsessions); (b) irresistible urges to repeat stereotyped or ritualistic acts (compulsions); (c) both of these in combination. See) anxiety disorders.

occipital cortex (visual cortex): the cortex of the occipital lobe.

occipital lobe { Figure }: posterior lobe of the brain which is involved with vision; portion of the cerebral hemisphere, behind the parietal and temporal lobes. See) frontal lobe.

olfaction: sense of smell.

olfactory bulb: region of the brain involved in olfaction (smell); it is a way station between the receptors in the nasal passage and the olfactory cortex.

olfactory cortex:

olfactory epithelium: specialized skin within the nasal cavity that contains the receptors for the sense of smell.

operant behavior (instrumental behavior): behavior defined by the stimulus to which it leads rather than by the stimulus that elicits it; such as behavior leading to reward.

operant conditioning (instrumental conditioning) (reward learning): strengthening of an operant response by presenting a reinforcing stimulus if, and only if, the response occurs . See) classical conditioning.

opiates (narcotics): opium or one of its chemical derivatives: codeine, morphine, or heroin. Central nervous system depressants that relieve pain and produce euphoria, all highly addictive.

opinion molecule: cognitive unit comprising a belief, an attitude, and a perception of social support for the individual's view on the matter. For example, 'I believe that Democrats are compassionate toward the poor' (belief); 'I prefer having Democrats in office' (attitude); 'And I think the American people agree with me' (perception of social support).

opioid receptors: neuroreceptor molecules in specific areas of the brain and spinal cord to which a group of neurotransmitters, called endorphins, bind. These molecules also have an affinity for opiates. There are several distinct types of opioid receptors; each has a different affinity for binding with various opiates.

opponent-color theory: theory of color perception that postulates two types of color-sensitive units that respond in opposite ways to the two colors of an opponent pair. One type of unit responds to red or green, the other to blue or yellow. Since a unit cannot respond in two ways at once, reddish-greens and yellowish-blues cannot occur. See) trichromatic theory, two-stage color theory.

optic chiasma { Figure }: Vision) cross-over junction of the optic nerves, located near the base of the brain, where nerve fibers from the inner half of each retina (nearest the nose) of the eye, cross to the opposite side of the brain. The resulting left optic tract carries data about objects seen in the right-hand side of the field of vision, and the right optic tract carries signals from objects seen on the left.

optic nerve { Figure }: Vision) a nerve formed out of axons of the ganglion cells, which leads to the brain. See) bipolar cells. ganglia, photoreceptors, retina.

oral stage: Freud's psychoanalytic theory) first stage of psychosexual development; pleasure derives from the lips and mouth, as in sucking at the mother's breast.

orienting reflex: (a) nonspecific response to change in stimulation involving depression of cortical alpha rhythm, galvanic skin response, pupillary dilation, and complex vasomotor responses (a term introduced by Russian psychologists). (b) Head or body movements that orient the organism's receptors to those parts of the environment in which stimulus changes are occurring.

osmoreceptors: hypothesized cells in the hypothalamus that respond to dehydration by stimulating the release of ADH by the pituitary gland, which, in turn, signals the kidneys to reabsorb water into the bloodstream. See) antidiuretic hormone, volumetric receptors.

otoliths: ear stones. See vestibular sacs.

outer ear: external ear and auditory canal, whose purpose is to funnel sound waves toward the inner ear. See) middle ear.

oval window: membrane on the cochlea of the inner ear that receives vibrations from the ear drum via three connecting bones (malleus, incus, and stapes). Vibrations at the oval window set up similar vibrations in the internal fluid of the cochlea, ultimately activating the hair cells that serve as auditory receptors.

ovarian hormones: See estrogen, progesterone.

overtone": a higher frequency tone, a multiple of the fundamental frequency, that occurs when a tone is sounded by a musical instrument. See) timbre.

perioqueductal gray (PAG): region of the midbrain involved in sensing pain. When PAG neuronsneurons are active, a neural gate is closed and consequently the sensation of pain is diminished.

PCP: phenylcyclidine.

PQRST method: technique for reading and studying information presented in textbook form. The method takes its name from the first letter of the five steps one follows in reading a textbook chapter: Preview, Question, Read, Self-recitation, Test.

pancreas: body organ located near the stomach. As a duct gland, it secretes pancreatic juice into the intestines, but some specialized cells function as an endocrine gland, secreting the hormone insulin into the bloodstream.

panic disorder: anxiety disorder in which the individual has sudden and inexplicable episodes of terror and feelings of impending doom accompanied by physiological symptoms of fear (such as heart palpitations, shortness of breath, muscle tremors, faintness).

parallel processing: theoretical interpretation of information processing in which several sources of information are all processed simultaneously. See) serial processing.

paranoid schizophrenia: schizophrenic reaction in which the patient has delusions of persecution. See) schizophrenia.

paraphilias: same as sexual perversions. Sexual attraction to unusual objects as well as sexual activities that are unusual in nature. Examples are fetishism (sexual attractions to an inanimate object or some specific nongenital part of a person), exhibitionism (obtaining sexual gratification by exposing one's genitals to an unwilling observer), and pedophilia (a preference for obtaining sexual gratification through contact with youngsters who are legally underage).

parapsychology (<=>beside psychology): subfield of psychology that studies psi phenomena (extrasensory perception and psychokinesis). See) clairvoyance, precognition, telepathy.

parasympathetic system: a division of the autonomic nervous system that serves to slow the heart rate, increase the intestinal and gland activity, and relax the sphincter muscles; together with the sympathetic nervous system, constitutes the autonomic nervous system; the nerve fibers of which originate in the cranial and sacral portions of the spinal cord. Active in relaxed or quiescent states of the body and to some extent antagonistic to the sympathetic system, or division. See) sympathetic system.

parathyroid glands: endocrine glands adjacent to the thyroid gland in the neck, whose hormones regulate calcium metabolism, thus maintaining the normal excitability of the nervous system. Parathyroid inadequacy leads to tetany. See) endocrine system.

parietal lobe { Figure }: portion of the cerebral hemisphere, behind the central fissure and between the frontal and occipital lobes. See) temporal lobe.

passionate love: intensely emotional state in which tender and sexual feelings, elation and pain, anxiety and relief, altruism and jealousy coexist in a confusion of feelings. Combines physiological arousal with perception that the arousal is evoked by the beloved. Contrasted with companionate love.

path analysis: correlational procedure that divides an overall correlation between two variables into separate components or paths. For example, path analysis can help to determine whether a link between childhood temper tantrums and later occupational problems is direct or is due to some intervening link like dropping out of school.

pathology:

pattern recognition: perceptual process of determining what an object is.

percept: result of the perceptual process; that which the individual perceives.

perception: general term to describe the whole process of how we come to know what is going on around us; the entire sequence of events from the presentation of a physical stimulus to the phenomenological experiencing of it. Perception is viewed as a set of subprocesses that occur in a multilevel, interactive system. The lower levels in this system, the parts closely associated with the sense organs, are called sensory processes.

perceptual constancy: tendency to see objects as relatively unchanged under widely altered conditions of illumination, distance, and position. See) color constancy, lightness constancy, location_constancy, shape constancy, size constancy.

perceptual defense: supposed prevention of an individual's conscious perceptual system from recognizing an anxiety-producing situation perceived by the individual's unconscious perceptual system.

perceptual patterning: tendency to perceive stimuli according to principles such as proximity, similarity, continuity, and closure. Emphasized by Gestalt psychologists. See) figure-ground organization.

performance: overt behavior, as distinguished from knowledge or information not translated into action. The distinction is important in theories of learning.

peripheral nervous system: that part of the nervous system outside the brain and spinal cord; it includes the autonomic nervous system and the somatic nervous system. See) autonomic nervous system, somatic nervous system.

personal construct: In George Kelly's theory of personality, a dimension used by an individual to interpret or 'construe' his or her environment. Considered by Kelly to be the basic unit of personality organization. See) Role Construct Repertory Test.

personality: the distinctive and characteristic patterns of thought, emotion, and behavior that define an individual's personal style of interacting with the physical and social environment.

personality assessment: the measurement or appraisal of personality.

personality inventory: an inventory for self-appraisal, consisting of many statements or questions about personal characteristics and behavior that the person judges to apply or not to apply to him or her. See) projective test.

personality psychologist: psychologist whose area of interest focuses on classifying individuals and studying the differences between them. This specialty overlaps both developmental and social psychologists to some extent.

phallic stage: Freud's psychoanalytic theory) third stage of psychosexual development in which gratification is associated with stimulation of the sex organs and sexual attachment is to the parent of the opposite sex. See) Oedipal conflict, psychosexual development.

phasic pain: the kind of sharp pain experienced immediately upon suffering an injury; usually brief with a rapid increase in intensity followed by a decrease. See) tonic pain.

phencyclidine (PCP): originally developed as an anesthetic but discontinued because of the bizarre reactions it produced, this drug causes an insensitivity to pain and makes the users feel dissociated from themselves and from their environments. Overdoses result in prolonged periods of stupor or coma.

phenomenological perspective: an approach to psychology that focuses on subjective experience and tries to describe it from each individual's unique perspective. See) humanistic psychology.

phenomenology: the study of an individual's subjective experience or unique perception of the world. Emphasis is on understanding events from the subject's point of view rather than focusing on behavior. See) humanistic psychology, introspection.

phenothiazines: group of antipsychotic drugs that relieve the symptoms of schizophrenia by blocking the access of the neurotransmitter dopamine to its receptors. Chlorpromazine (Thorazine) and fluphenazine (Prolixin) are examples.

phenotype: genetics) the characteristics that are displayed by the individual organism such as eye color or intelligence as distinct from those traits that one may carry genetically but not display. See) genotype.

pheromones: chemicals secreted by many animals that float through the air to attract other members of the same species. They represent a primitive form of communication.

phi phenomenon: stroboscopic motion is its simpler form. Commonly produced by successively turning on and off two separated stationary light sources; as the first is turned off and the second turned on, the subject perceives a spot of light moving from the position of the first to that of the second. See) stroboscopic motion.

phobia: excessive fear in the absence of real danger. See) agoraphobia, claustrophobia.

phobic disorder: an anxiety disorder in which phobias are severe or pervasive enough to interfere seriously with the individual's daily life.

phoneme: smallest unit in the sound system of a language; it serves to distinguish utterances from one another. See) morpheme.

photopigments: chemicals contained in the rods and cones (the receptor cells in the eye). These chemicals absorb light, which starts a process that results in a neural impulse.

physiological motive: motive based on an evident bodily need, such as the need for food or water.

Piaget's cognitive stages:

pitch: a qualitative dimension of hearing correlated with the frequency of the sound waves that constitute the stimulus. Higher frequencies yield higher pitches. See) loudness, timbre.

pituitary gland: (hypophysis) an endocrine gland joined to the brain just below the hypothalamus. It consists of two parts, the anterior pituitary and the posterior pituitary. The anterior pituitary is the more important part because of its regulation of growth and of other endocrine glands . See) endocrine system.

place theory of pitch: theory of hearing that associates pitch with the place on the basilar membrane where activation occurs. See) temporal theory of pitch.

placebo: an inert substance used in place of an active drug; given to the control group in an experimental test.

pleasure principle: Freud's psychoanalytic theory) strategy followed by the id, seeking to obtain pleasure and to avoid pain regardless of external circumstances. See) reality principle.

pluralistic ignorance: tendency for persons in a group to mislead each other about a situation; for example, to define an emergency as a nonemergency because others are remaining calm and are not taking action.

polygraph (lie detector) (voice stress analyzer): device that measures simultaneously several physiological responses that accompany emotion; for instance, heart and respiration rate, blood pressure, and GSR. Commonly known as a 'lie detector' because of its use in determining the guilt of a subject through responses while he or she answers questions. See) GSR, voice stress analyzer.

population: total universe of all possible cases from which a sample is selected. The usual statistical formulas for making inferences from samples apply when the population is appreciably larger than the sample, for instance, 5 to 10 times larger than the sample.

positive incentive: object or circumstance toward which behavior is directed when the object or circumstance is perceived or anticipated. See) negative incentive.

positive reinforcement: reinforcing a response by the presentation of a positive stimulus. See) positive reinforcer.

positive reinforcer (reward): any stimulus that, when applied following a response, increases the probability of the response . See) negative reinforcer.

positive symptoms: schizophrenia) behavioral excesses such as hallucinations and bizarre behavior. Contrasted with negative symptoms and presumed to be caused by irregularities in neural transmission.

positron emission tomography (PET scan): computer-based scanning procedure that measures regional changes in blood flow to map the neural activities of the living brain.

post-traumatic stress disorder: an anxiety disorder in which a stressful event that is outside the range of usual human experience, such as military combat or a natural disaster, brings in its aftermath such symptoms as a re-experiencing of the trauma and avoidance of stimuli associated with it, a feeling of estrangement, a tendency to be easily startled, nightmares, recurrent dreams, and disturbed sleep.

posterior attentional system: neural structures in the back of the brain that mediate our ability to selectively attend to a particular location.

posthypnotic amnesia: a particular form of posthypnotic suggestion in which the hypnotized person forgets what has happened during the hypnosis until signaled to remember.

posthypnotic suggestion: a suggestion made to a hypnotized person that he or she will perform in a prescribed way (commonly to a prearranged signal) when no longer hypnotized. The activity, the posthypnotic response, is usually carried out without the subject's awareness of its origin. See) hypnosis.

pragmatic rules: rules used in deductive reasoning that are less abstract than logical rules, but still applicable to many different domains of life. An example is the permission rule.

precognition: perception of a future event that could not be anticipated through any known inferential process (for example, predicting that a particular number will come up on the next throw of dice). See) clairvoyance, extrasensory perception, parapsychology, psi, psychokinesis, telepathy.

preconscious: Freud's topograhic model) the part of the mind containing thoughts and memories that are not part of conscious awareness at the moment, but which can be brought to awareness when needed. See) unconscious.

preferential looking method: A method of examining infants' perceptual preferences by presenting them two stimuli simultaneously and noting the amount of time the infants gaze at each object.

prejudice: (<= pre-judgment) negative feelings toward a group. Usually implies negative feelings not based on adequate or valid data about the group. See) attitude, discrimination, stereotype.

preoperational stage: Piaget's second stage of cognitive development (ages 2-7 years). The child can think in terms of symbols but does not yet comprehend certain rules or operations, such as the principle of conservation. See) conservation.

prepared conditioning: proposal that humans are biologically predisposed, or prepared, by evolutionary selection to associate fear with objects or situations that were dangerous in earlier times. Explains why people develop phobias (conditioned fears) of snakes and heights but not of lambs or guns. See) classical conditioning.

presynaptic cell membrane:

post-synaptic cell membrane:

primacy effect: (a) In memory experiments, the tendency for initial words in a list to be recalled more readily than later words. (b) In studies of impression formation, the tendency for initial information to carry more weight than information received later.

primary abilities: abilities, discovered by factor analysis, that underlie intelligence test performance.

primary auditory area: brain region located at the top of the temporal lobe of each cerebral hemisphere where auditory signals carried by the acoustic nerve are analyzed. Because nerve fibers from each side of the head cross over at the brain stem before reaching the auditory area, signals from each ear reach both temporal lobes. Thus, damage to one lobe does not produce deafness in one ear.

primary motor area: projection area in the brain lying in front of the central fissure. Electrical stimulation commonly results in movement, or motor, responses. See) primary somatosensory area.

primary sex characteristics: structural or physiological characteristics that make possible sexual union and reproduction. See) secondary sex characteristics.

primary somatosensory area (body-sense area): area in the parietal lobe of the brain that registers sensory experiences, such as heat, cold, touch, and pain . See) primary motor area.

primary visual area: projection area lying in the occipital lobe. In humans, damage to this area produces blindness in portions of the visual field corresponding to the amount and location of the damage.

priming: increased accessibility or retrievability of information stored in memory produced by the prior presentation of relevant cues.

proactive interaction: interaction between individuals and their environments that arises because different individuals choose to enter different situations and to shape those situations differently after entering them. See) evocative_interactionevocative interaction, reactive interaction.

proactive interference: interference of earlier learning with the learning and recall of new material. See) retroactive interference.

probe: studies of memory) an item from a list to be remembered that is presented as a cue to the subject; for example, the subject could be asked to give the next item in the list.

problem-focused coping: reducing anxiety or stress by dealing in some way with the anxiety-producing situation. Escaping the situation or finding a way to alter it are examples. See) emotion-focused coping.

problem-solving strategies: various strategies that can be employed in solving a problem. Of special interest are a class of strategies that involve breaking the solution to a problem into a series of subgoals. The subgoals are to be accomplished as intermediate steps toward ultimately reaching the final goal.

product-moment coefficient:

product-moment correlation: See coefficient of correlation.

progesterone: female hormone secreted by the ruptured follicle.

program: (a) a plan for the solution of a problem; often used interchangeably with 'routine' to specify the precise sequence of instructions enabling a computer to solve a problem. (b) in teaching, a set of materials arranged so as to maximize the learning process.

projection: defense mechanism by which people protect themselves from awareness of their own undesirable traits by attributing those traits excessively to others. See) defense mechanisms.

projective test: personality test in which subjects reveal ('project') themselves through imaginative productions. The projective test gives much freer possibilities of response than the fixed-alternative personality inventory. Examples of projective tests are the Rorschach Test and the Thematic Apperception Test.

prolactin: pituitary hormone prompting the secretion of milk.

proposition: sentence or component of a sentence that asserts something (the predicate) about somebody or something (the subject). All sentences can be broken into propositions.

prosopagnosia: loss in the ability to recognize faces that results from brain damage.

prototype: part of a concept that contains the properties that describe the best examples of the concept. See) core.

psi: processes of information and/or energy exchange not currently explicable in terms of known physical mechanisms. See) clairvoyance, extrasensory perception, parapsychology, precognition, psychokinesis, telepathy.

psychiatric nurse: nurse specially trained to deal with patients suffering from mental disorders.

psychiatric social worker: social worker trained to work with patients and their families on problems of mental health and illness, usually in close relationship with psychiatrists and clinical psychologists. See) clinical psychologist, psychiatrist.

psychiatrist: medical doctor specializing in the treatment and prevention of mental disorders both mild and severe. See) clinical psychologist, psychoanalyst.

psychiatry: branch of medicine concerned with mental health and mental illness. See) psychiatrist, psychoanalyst.

psychoactive drugs: drugs that affect behavior and thought processes. See) depressants, hallucinogens, stimulants.

psychoanalysis (psychoanalytic_theory): (a) the method developed by Freud and extended by his followers for treating mental disorders. (b) The theory of personality which grew out of experiences with the psychoanalytic method of treatment. The theory emphasizes the role of unconscious processes in personality development and in motivation.

psychoanalyst: a psychotherapist, usually trained as a psychiatrist, who uses methods related to those originally proposed by Freud for treating neuroses and other mental disorders. See) clinical psychologist.

psychoanalytic perspective: an approach to psychology that tries to explain certain kinds of behaviors in terms of unconscious beliefs, fears, and desires. See) psychoanalysis.

psychoanalytic psychotherapy: a method of treating mental disorders based on the theories of Freud but briefer and less intense than psychoanalysis. Less emphasis on exploration of childhood experiences and more attention to the client's current interpersonal problems. See) psychoanalysis.

psychoimmunology: area of research in behavioral medicine that studies how the body's immune system is affected by psychological variables.

psychokinesis (PK): mental influence over physical events without the intervention of any known physical force (for example, willing that a particular number will come up on the throw of dice). See) clairvoyance, extrasensory perception, parapsychology, precognition, psi, telepathy.

psycholinguistics: study of the psychological aspects of language and its acquisition.

psychological dependence: habitual use of a drug to relieve anxiety even though no physical dependence (addiction) has developed.

psychological determinism: doctrine that all thoughts, emotions, and actions have causes.

psychological motive: motive that is primarily learned rather than based on biological needs.

psychology: social science that studies behavior and mental processes.

psychometric function: curve plotting the percentage of times the subject reports detecting a stimulus against a measure of the physical energy of the stimulus.

psychopathic personality: See antisocial personality.

psychopharmacology: study of the effects of drugs on behavior.

psychophysical methods: procedures used to determine thresholds of sensory modalities.

psychophysics: name used by Fechner for the science of the relationship between mental processes and the physical world. Now usually restricted to the study of the sensory consequences of controlled physical stimulation.

psychosexual development (psychosexual stages): Freud's psychoanalytic theory) idea that development takes place through stages (oral, anal, phallic, latent, genital), each stage characterized by a zone of pleasurable stimulation and appropriate objects of sexual attachment, culminating in adult sexuality. See) anal stage, genital stage, latency, oral stage, psychosocial stages.

psychosis (Pl. psychoses): severe mental disorder in which thinking and emotion are so impaired that the individual is seriously out of contact with reality. No longer a major diagnostic category in DSM-IV. See) psychotic behavior.

psychosocial stages: modification by Erikson of the psychoanalytic theory of psychosexual development, giving more attention to the social and environmental problems associated with the various stages of development and adding some adult stages beyond genital maturing. See) psychosexual development.

psychosomatic disorder (psychophysiological disorder): physical illness that has psychological causes.

psychotherapy: treatment of personality malajdustment or mental disorders by psychological means, usually, but not exclusively, through personal consultation. See) biological therapy.

psychotic behavior: behavior indicating gross impairment in reality contact as evidenced by delusions and/or hallucinations. May result from damage to the brain or from a mental disorder such as schizophrenia or a bipolar disorder. See) psychosis.

puberty: period during which the reproductive organs become functionally mature. The development of the secondary sex characteristics (particularly the growth and pigmentation of underarm and pubic hair) marks the onset of puberty and the capacity for reproduction, the culmination. See) adolescent growth spurt, secondary sex characteristics.

punishment: procedure used to decrease the strength of a response by presenting an aversive stimulus whenever the response occurs. Note that such a stimulus when applied would be a punisher; when removed, it would act as a negative reinforcer, reinforcing whatever led to its removal.

pupil: the eye) a circular opening in the iris (the colored part of the eye) that expands and contracts, varying according to the intensity of light present. See) cornea, lens, retina.

pure alexia: loss of the ability to recognize words that results from brain damage (in the left occipital lobe).

Q sort: assessment technique by which a rater provides a systematic description of an individual's personality by sorting a set of personality statements (for example, 'Has a wide range of interests') into groups, ranging from those that are least descriptive to those that are most descriptive of the individual.

rapid eye movements (REMS): eye movements that usually occur during dreaming and that can be measured by attaching small electrodes laterally to and above the subject's eye. These register changes in electrical activity associated with movements of the eyeball in its socket.

rapport: (a) a comfortable relationship between the subject and the tester, ensuring cooperation in replying to test questions. (b) a comfortable relationship relationship between therapist and patient. (c) a special relationship of hypnotic subject to hypnotist.

rating scale: device by which raters can record their judgments of others (or of themselves) on the traits defined by the scale.

ratio schedules: operant conditioning) reinforcement schedules where reinforcement depends on the number of responses the organism makes. On a fixed ratio (FR) schedule, the number of responses required is fixed at a particular value (for example, five responses for a reinforcement). On a variable ratio (VR) schedule, reinforcement occurs only after a certain number of responses, but that number varies unpredictably (for example, sometimes one response, other times ten, but with an average of five). See) interval schedules.

rationalization: defense mechanism in which self-esteem is maintained by assigning plausible and acceptable reasons for conduct entered on impulsively or for less than acceptable reasons. See) defense mechanisms.

reaction formation: defense mechanism in which a person denies a motive (which may be disapproved of) through giving strong expressions to its opposite. See) defense mechanisms.

reaction time: time between the presentation of a stimulus and the occurrence of a response. See) latency.

reactive interaction: interaction between individuals and their environments that arises because different individuals interpret, experience, and react to situations in different ways. See) evocative interaction, proactive interaction.

reality principle: Freud's psychoanalytic theory) strategy followed by the ego, holding back the impulses of the id until they can be satisfied in socially approved ways. See) pleasure principle.

receiver-operating-characteristic curve (ROC curve): function relating the probability of hits and false alarms for a fixed signal level in a detection task. Factors influencing response bias may cause hits and false alarms to vary, but their variation is constrained to the ROC curve. See) signal detection task.

recency effect: memory experiments) tendency for the last words in a list to be recalled more readily than other list words.

receptive field: vision) a region of the retina that is associated with a specific cortical neuron; when a stimulus appears anywhere in the field, the associated neuron fires. See) feature detector.

receptor cell (receptor): specialized cell sensitive to particular kinds of stimuli and connected to nerves composed of afferent neurons (such as the retina of the eye). loosely) organ containing these sensitive portions (such as the eye or the ear).

recessive gene: member of a gene pair that determines the characteristic trait or appearance of the individual only in the other member of the pair is recessive. If the other member of the pair is dominant, the effect of the recessive gene is masked. See) dominant gene.

recoding: process for improving short-term memory by grouping items into a familiar unit or chunk.

recognition: to recognize something is to associate it correctly with a category, such as 'chair,' or with a specific name, such as 'John Jones.' It is a high-level process that requires learning and remembering.

red-green color blindness: most common form of color blindness, a variety of dichromatism.

reduced stimulation study (sensory deprivation study): experiment whereby sensory stimulation is markedly reduced.

reductionism: psychology) an explanation that tries to explain (or reduce) psychological notions to biological ones.

reference group: group to which an individual refers for comparing, judging, and deciding on his or her opinions and behaviors. We are said to 'identify' with such groups. See) identification.

refractory phase: period of temporary inactivity in a neuron after it has fired once.

registration: describes receptive processing in which information is processed but not perceived. See) perception.

regression: return to more primitive or infantile modes of response.

rehearsal: conscious repetition of information in short-term memory, usually involving speech. The process facilitates the short-term recall of information and its transfer to long-term memory. See) dual-memory theory.

reincarnation: rebirth (after death); that a peole have lived prior lives.

reinforcement: classical conditioning) experimental procedure of following the conditioned stimulus by the unconditioned stimulus. operant conditioning) the analogous procedure of following the occurrence of the operant response by the reinforcing stimulus. or) process that increases the strength of conditioning as a result of these arrangements. See) negative reinforcement, partial reinforcement, positive reinforcement.

reinforcement schedule: defined procedure for reinforcing a given response only some proportion of the time it occurs. See) interval schedules, partial reinforcement, ratio schedules.

reinforcing stimulus (reinforcer): classical conditioning) the unconditioned stimulus; operant conditioning) the stimulus that reinforces the operant (typically, a reward). See) negative reinforcer, positive reinforcer.

relative size: perception) a monocular cue for depth. If an image contains an array of objects of similar shape, the smaller objects are perceived as being farther away. See) distance cues, linear perspective, relative height, superposition.

relaxation training: training in various techniques for relaxing muscle tension. The procedure is based on Jacobson's progressive relaxation method, in which the person learns how to relax muscle groups one at a time, the assumption being that muscular relaxation is effective in bringing about emotional relaxation.

releaser: ethology) a stimulus that sets off a cycle of instinctive behavior. See) instinct.

reliability: self-consistency of a test as a measuring instrument. Reliability is measured by a coefficient of correlation between scores on two halves of a test, alternate forms of the test, or retests with the same test; a high correlation signifies high consistency of scores for the population tested. See) validity.

repression: (a) defense mechanism in which an impulse or memory that is distressing or might provoke feelings of guilt is excluded from conscious awareness. See) suppression. (b) A theory of forgetting.

Rescorla-Wagner model: of classical conditioning) assumes that the amount of conditioning between a conditioned stimulus and an unconditioned stimulus on any trial depends on the predictability of the unconditioned stimulus; the less predictable the unconDitioned stimulus, the greater the amount of conditioning.

resistance: psychoanalysis) blocking of free association; a psychological barrier against bringing unconscious impulses to the level of awareness; part of the process of maintaining repression. See) interpretation.

respondent behavior (elicited behavior): corresponding to reflex action, in that it is largely under the control of and predictable from the stimulus. See) operant behavior.

response: (a) behavioral result of stimulation in the form of a movement or glandular secretion. (b) any activity of the organism, including central responses (such as an image or fantasy) regardless of whether the stimulus is identified and whether identifiable movements occur. (c) products of the activity.

resting potential: electrical potential across the nerve cell membrane when it is in its resting state (not responding to other neurons); the inside of the cell membrane is slightly more negative than the outside. See) action potential.

reticular formation: system of ill-defined nerve paths and connections within the brain stem, lying outside the well-defined nerve pathways, and important as an arousal mechanism.

retina: the eye) portion sensitive to light, containing the rods and the cones.

retinal image: projected onto the retina by an object in the visual field.

retinal size: size of the retinal image of an object; decreases in direct proportion to the object's distance. See) object size.

retrieval: locating information in memory.

retrieval cue: can help retrieve information from memory.

retroactive interference: something subsequently learned that interferes with the recall of something learned earlier. See) proactive interference.

retrograde amnesia: loss of memory for events and experiences occurring in a period of time prior to the amnesia-causing trauma. See) anterograde amnesia.

reuptake: process by which a neurotransmitter is 'taken up' again (reabsorbed) by the synaptic terminals from which it had been released.

reward: synonym for positive reinforcement.

right hemisphere (minor hemisphere): right cerebral hemisphere. Controls the left side of the body and, for most people, spatial and patterned activities . See) cerebral hemispheres, corpus callosum, left hemisphere, split-brain subject.

rod: element of the retina of the eye mediating achromatic sensation only; particularly important in peripheral vision and night vision. See) cone.

Role Construct Repertory Test (Rep Test): measuring instrument devised by George Kelly for eliciting personal constructs.

role-playing: method for teaching attitudes and behaviors important to interpersonal relations by having the subject assume a part in a spontaneous play, whether in psychotherapy or in leadership training.

Rorschach Test: type of projective test whereby ink blots to be interpreted.

Saccade: quick movement of the eyes between eye fixations.

Schacter-Singer theory: of emotions stating that environmental stimuli lead to general physiological arousal; the individual's cognitive appraisal of the arousal then leads to the subjective experience of a specific emotion.

sadism: pathological motive that leads to inflicting pain on another person. See) masochism.

safety signal hypothesis: that the reason organisms prefer predictable to unpredictable aversive events is because predictability provides a safe period.

sample: selection of scores from the population (a total set of scores). If selection is random, an unbiased sample results; if selection is nonrandom, the sample is biased and unrepresentative.

satiety sensors: detectors located in different parts of the digestive or thirst systems that signal that the needed nutrients or fluids are on their way and that feeding or drinking can stop.

saturation: color) dimension that describes purity of hue or lack of gray; a color of low saturation appears to have a great deal of gray mixed with it.

scaling: converting raw data into types of scores more readily interpreted, such as ranks, centiles, standard scores.

scapegoat: form of displaced aggression in which an innocent but helpless victim is blamed or punished as the source of the scapegoater's frustration. See) scapegoat theory of prejudice.

scapegoat theory of prejudice: that some hostility toward minority groups arises because prejudiced individuals repress their own unacceptable impulses and then express hostile attitudes toward others who are perceived to possess those same impulses. The hostility often takes the form of blaming the group for both personal and societal problems.

schedule of reinforcement: frequency and/or timing with which reinforcement occurs. See) ratio schedules, interval schedules.

schema: cognitive structures stored in memory that are abstract representations of events, objects, and relationships in the real world; a key ingredient of cognitive theories of psychological phenomena. See) cognitive map, schematic processing.

schematic processing: cognitive process of searching for the schema in memory that is most consistent with the incoming information.

schizoid: having some characteristics that resemble schizophrenia but are less severe. Occurs with higher frequency in families of schizophrenics and thus tends to support a genetic basis for schizophrenia.

schizophrenia: group of mental disorders characterized by major disturbances in thought, perception, emotion, and behavior. Thinking is illogical and usually includes delusional beliefs; distorted perceptions may take the form of hallucinations; emotions are flat or inappropriate; bizarre behavior includes unusual postures, stereotyped movements, and 'crazy talk.' The individual withdraws from other people and from reality. Inherited brain or biochemical abnormalities are implicated.

school psychologist: professional psychologist employed by a school or school system, with responsibility for testing, guidance, research, and so on. See) educational psychologist.

second order conditioning: conditioning in which the unconditioned stimulus (UCS) is not biologically significant (such as food, water, or shock) but gains power as a UCS by being consistently paired with a biologically significant UCS. See) classical conditioning.

secondary sex characteristics: physical features distinguishing the mature male from the mature female, apart from the reproductive organs. (eg, a male's deeper voice and beard). See) primary sex characteristics.

selective adaptation: perception) loss of sensitivity to motion that occurs when we view motion. The adaptation is selective because we lose sensitivity to the motion viewed, and to similar motions, but not to motion that differs significantly in direction or speed. Presumably the result of fatigued neurons in the cerebral cortex.

selective attention: perceptual processes whereby certain input are selected for recognition, to the exclusion of others.

selective breeding: method of studying genetic influences by mating animals that display certain traits and selecting for breeding from among their offspring those that express the trait. If the trait is primarily determined by heredity, continued selection for a number of generations will produce a strain that breeds true for that trait.

self-actualization: fundamental tendency toward maximal realization of potentials; a basic concept in humanistic theories of personality such as those developed by Maslow and Rogers.

self-concept: composite of ideas, feelings, and attitudes about oneself. For some theorists, this is synonymous with the self.

self-consciousness: state of heightened self-awareness; the disposition to be self-attentive.

self-perception: awareness of oneself; differs from self-consciousness because it may take the form of objective self-appraisal. See) self-consciousness.

self-perception theory: that attitudes and beliefs are influenced by observations of one's own behavior; sometimes we judge how we feel by observing how we act.

self-regulation: behavior therapy) monitoring one's own behavior and using techniques such as self-reinforcement or controlling stimulus conditions to modify maladaptive behavior. See) behavior therapy.

self-schema (self-concept): generalization or theory about oneself derived from past experience. Self-schemata are assumed to influence the way we selectively attend to, process, and recall personally relevant information . See) schema.

semantic memory: stores general knowledge, such as the meanings of words. Knowledge is encoded in relation to other knowledge rather than in relation to the memorizer. See) episodic memory.

semicircular canals: inner ear) three curved tubular canals, in three planes, which form part of the labyrinth and are concerned with equilibrium and motion. See) equilibratory senses.

sensation: conscious experience associated with a very simple stimulus like the onset of a tone or light. At one time, the distinction between sensation and perception had great theoretical importance with perception viewed as a combination of sensations. Today, the dividing line between sensation and perception is much less clear, and it seems best to view such experiences as lying along a continuum.

sense receptors:.

sensitization: simple form of learning in which an organism learns to strengthen its reaction to a weak stimulus if a threatening or painful stimulus follows.

sensorimotor stage: Piaget's first stage of cognitive development (birth-2 years) during which the infant discovers relationships between sensations and motor behavior. See) object permanance.

sensory adaptation: reduction in sensitivity that occurs with prolonged stimulation and the increase in sensitivity that occurs with lack of stimulation; most noted in vision, smell, taste, and temperature sensitivity. See) dark and light adaptation.

sensory modalities: the individual senses.

sensory neuron (afferent neuron): neuron or nerve cell that conveys messages to the brain or spinal cord from the sense receptors and informs the organism about events in the environment or within the body . See) motor neuron, receptor.

sensory processes: subprocesses of the perceptual system that are closely associated with the sense organs and provide selectively filtered information about the stimuli that impinge on us; higher-level processes use this information to form a mental representation. See) filter, perception.

sensory-neural loss: hearing deficit in which threshold elevation (loss of sensitivity) is greater at high rather than low frequencies. See) conduction loss.

septal area: portion of the brain deep in the central part, between the lateral ventricles, that appears to yield a state akin to pleasure when stimulated electrically.

serial memory search: comparing a test stimulus in sequence to each item in short-term memory.

serial processing: theoretical interpretation of information processing in which several sources of information are processed in a serial order; only one source being attended to at a time. See) parallel processing.

serotonin: neurotransmitter in both the peripheral and central nervous systems. It is an inhibitory transmitter whose actions have been implicated in various processes including sleep, the perception of pain, and mood disorders (depression and manic-depression). See) neurotransmitter.

serotonin reuptake inhibitors: class of antidepressant drugs that work by increasing levels of the neurotransmitter serotonin in the synapse.

set point: weight at which an individual body functions best.

sex role: set of attitudes and behaviors that a society considers appropriate for the individual of a certain sex. See) sex typing.

sex typing: acquisition of attitudes and behaviors that a society considers appropriate for the individual because of sex. Distinguished from gender identity, which is the degree to which one regards oneself as male or female. See) sex role.

sex-linked trait: trait determined by a gene transmitted on the same chromosomes that determine sex, such as red-green color blindness. See) X, Y chromosome.

shape constancy: tendency to see a familiar object as of the same shape regardless of the viewing angle. See) perceptual constancy.

shaping of behavior: modifying operant behavior by reinforcing only those variations in response that deviate in the direction desired by the experimenter.

short-term memory (STM): component of the memory system with limited capacity that maintains information for only a brief time. See) long-term memory.

sibling: a brother or sister.

signal detection task: procedure whereby the subject must judge on each trial whether a weak signal was embedded in a noise background.  See) receiver-operating-characteristic curve.

signal detection theory: of the sensory and decision processes involved in psychophysical judgments, with special reference to the problem of detecting weak signals in noise. See) signal detection task.

simple cell: Visual Cortex) responds to a bar of light or straight edge of a particular orientation and location in the visual field. See) complex cell.

simple phobia: excessive fear of a specific object, animal, or situation in the absence of real danger. See) phobia, phobic disorder.

sine wave: cyclical wave that when plotted corresponds to the plot of the trigonometric sine function. The sound waves of pure tones yield this function when plotted.

situational attribution: attributing a person's actions to factors in the situation or environment, as opposed to internal attitudes and motives. See) dispositional atttribution.

size constancy: tendency to see a familiar object as of its actual size regardless of its distance. See) perceptual constancy.

size-distance invariance principle: that the perceived size of an object is equal to the product of the retinal size of the object and the perceived distance of the object.

smooth muscle: found in the digestive organs, blood vessels, and other internal organs. Controlled via the autonomic nervous system. See) cardiac and striate muscle.

social facilitation: phenomenon by which an organism performs responses more rapidly when other members of its species are present.

social norms: unwritten rules of a group or community that governs members' behavior, attitudes, and beliefs.

social phobia: extreme insecurity in social situations accompanied by an exaggerated fear of embarrassing oneself. See) phobia, phobic disorder.

social psychologist: studies social interaction and the ways that individuals influence one another.

social-learning theory (social behavior theory): application of learning theory to personal and social behavior .

socialization: training provided by a social environment that shapes individual characteristics and behavior.

sociology: science dealing with group life and social organization in literate societies. See) behavioral sciences.

sociopathic personality: see antisocial personality.

somatic nervous system: division of the peripheral nervous system consisting of nerves that connect the brain and spinal cord with the sense receptors, muscles, and body surface. See) autonomic nervous system.

spatial frequency: perception) distance between successive dark bars in a grating consisting of alternating dark and light bars. Spatial frequency is a determinant of visual resolution. See) contrast sensitivity.

spatial localization: perceptual process of determining where in the visual field an object is. See) pattern recognition.

spatial resolution: ability to see spatial patterns. Visual actuity and the contrast threshold are measures of spatial resolution.

speaker's intention: goal in uttering a particular sentence, which is distinct from the actual content of the sentence.

specific hunger: hunger for a specific food incentive, such as a craving for sweets. See) hunger drive.

specific nerve energies: Johannes Muller's proposal that the brain codes qualitative differences between sensory modalities by the specific neural pathways involved.

spindle: EEG) characteristic of Stage 2 sleep, consisting of short bursts of rhythmical responses of 13-16 Hz; slightly higher than alpha.

split-brain subject: person with a severed the corpus callosum which separates the functions of the two cerebral hemispheres; generally due to a medical operation.  See) cerebral hemispheres.

spontaneous recovery: classical conditioning - Pavlov) reappearance of a conditioned response within a new context after an organism undergoes execution of the conditioned response in the original context.

spontaneous remission: recovery from an illness or improvement without treatment.

sports psychology: study of human behavior in sport. The goal of much of the work is to help athletes develop psychological skills that maximize performance and enhance the sport experience. Examples) hypnosis and biofeedback have been used to control an athlete's anxiety level during competition; mental imagery has been employed to help perfect the synchrony and flow of certain body movements.

spreading activation: a model of retrieval from long-term memory in which activation subdivides among paths emanating from an activated mental representation.

spurious association: plausible but nonexistent relation between two stimuli. Human learners frequently report such relations when trying to learn less-than-perfect relations.

stabilized retinal image: image of an object on the retina when special techniques are used to counteract the minute movements of the eyeball that occur in normal vision. When an image is thus stabilized it quickly disappears, suggesting that the changes in stimulation of retinal cells provided by the eye movements are necessary for vision.

stages of development: developmental periods, usually following a progressive sequence, that appear to represent qualitative changes in either the structure or the function of the organism (such as Freud's psychosexual stages or Piaget's cognitive stages).

standard deviation (root mean square deviation): square root of the mean of the squares of the amount by which each case departs from the mean of all the cases.

state-dependent learning: Learning that occurs during a particular biological state (such as when drugged) so that it is most effective when the person is put in the same state again.

statistical significance: reliability of an obtained statistical measure as a statement about reality.

statistics: sampling data from a population of individuals and mathematically drawing inferences about the population from the sample. See) statistical significance.

stereoscopic vision: binocular perception of depth and distance of an object owing to the overlapping fields of the two eyes; equivalent effect when slightly unlike pictures are presented individually to each eye in a stereoscope. See) distance cues.

stereotype: schema of the personality traits or physical attributes of a class or group of people; usually an overgeneralization, leading to mistaken assumptions that every member of the group possesses the particular characteristic.

steroids: chemical substances, of which some are prominent in the secretions of the adrenal cortex and may be related to some forms of mental illness. See) adrenal gland.

stimulants: psychoactive drugs that increase arousal. Examples) amphetamines, cocaine, and caffeine

stimulation-produced analgesia: analgesic effect produced by the stimulation of a region of the midbrain. See) gate control theory of pain.

stimulus-response psychology (S-R psychology): view that all behavior is in response to stimuli and that the appropriate tasks of psychological science are those identifying stimuli, the responses correlated with them, and the processes intervening between stimulus and response.

strabismus: vision) lack of binocular depth perception caused by a person's eyes not pointing in the same direction early in life. See) astigmatism.

stress: state occuring when events, perceived as endangering physical or psychological well-being, are encountered.

stress responses: reactions to stress-causing events, which may include bodily changes that prepare for emergency (fight-or-flight response) as well as such psychological reactions as anxiety, anger and aggression, apathy and depression, and cognitive impairment.

stressors: events perceived as endangering one's physical or psychological well-being.

striate muscle: striped muscle; the characteristic muscles controlling the skeleton, as in the arms and legs; activated by the somatic, as opposed to the autonomic, nervous system. See) cardiac and smooth muscle.

stroboscopic motion: illusion of motion resulting from the successive presentation of discrete stimulus patterns arranged in a progression corresponding to movement, such as motion pictures. See) phi phenomenon.

subtractive mixture: color) mixture occurring when transparent colored filters are placed one in front of the other and when pigments are mixed; results differ from additive mixture obtained by mixing projected lights.

superego: Freud's tripartite division of the personality) represents the internalization of the values and morals of society; the conscience that controls the expression of the id's impulses through moral scruples. See) ego.

superposition: perception) monocular cue for depth. If an object has contours that cut through those of another, obstructing the other object's view, the overlapping object is perceived as being nearer. See) distance cues, linear perceptive, relative height, relative size.

suppression: process of self-control in which impulses, tendencies to action, and wishes to perform disapproved acts are in awareness but not overtly revealed. See) repression.

survey method: obtaining information by questioning a large sample of people.

symbol: anything that stands for or refers to something other than itself.

sympathetic system: division of the autonomic nervous system serving to accelerate the heart rate, constrict blood vessels, and raise blood pressure; together with the parasympathetic nervous system constitutes the autonomic nervous system; active in emotional excitement and to some extent antagonistic to the parasympathetic system; characterized by a chain of ganglia on either side of the spinal cord, with nerve fibers originating in the thoracic and lumbar portions of the spinal cord.

synapse: the close functional connection between the axon of one neuron and the dendrites or cell body of another neuron. See) excitatory synapse, inhibitory synapse.

synaptic gap: space between the presynaptic cell membrane and the post-synaptic cell membrane; the space across a synapse.

synaptic terminals: small swellings at the end of axon branches that enclose synaptic vesicles containing neurotransmitters. See) synapse.

synaptic vesicles: small spherical or irregularly shaped structures within a synaptic terminal that contain neurotransmitters; when stimulated, they discharge the neurotransmitters. See) synapse.

syntactic analysis: Language) structural analysis that divides a sentence into noun phrases and verb phrases and divides phrases into units like nouns, adjectives, and verbs.

systematic desensitization: behavior therapy technique in which hierarchies of anxiety-producing situations are imagined (or sometimes confronted in reality) while the person is in a state of deep relaxation in order to gradually dissociate the situations from the anxiety response. See) anxiety hierarchy, behavior therapy, counterconditioning.

systematic reinforcement: Behavior Therapy) method for modifying behavior by reinforcing desirable responses (with praise or tangible rewards) and ignoring undesirable ones.

T-cell (thymus-dependent cell): type of lymphocyte that recognizes and destroys foreign antigens and thus plays an important role in the body's immune response.

Thematic Apperception Test (TAT): a type of projective test that utilizes pictures that elicit stories.

tabula rasa: [L. => blank slate]. referring to the view that human beings are born without any innate knowledge or ideas; all knowledge is acquired through learning and experience. Proposed by the 17th to 18th-century British empiricists (Locke, Hume, Berkeley, Hartley).

tachistoscope (T-scope): instrument for the brief exposure of words, symbols, pictures, or other visually presented material; sometimes called a .

taste buds: receptors for taste located in clusters on the tongue and around the mouth.

telegraphic speech: Child Speach Development) stage in which the child preserves only the most meaningful and perceptually salient elements of adult speech are preserved, tending to omit prepositions, articles, prefixes, suffixes, and auxiliary words.

telepathy: thought transference without a known mediation channel for sensory communication.  See) clairvoyance, extrasensory perception, parapsychology, precognition, psi, psychokinesis.

temperament: characteristic mood, sensitivity to stimulation, and energy level, usually conceptualized as a genetic predisposition because of striking differences in reactivity to stimulation, general mood, and activity level observed in newborns.

temperature regulation: process by which an organism keeps its body temperature relatively constant.

temporal lobe { Figure }: portion of the cerebral hemisphere, at the side below the lateral fissure and in front of the occipital lobe. See) frontal lobe, parietal lobe.

temporal theory of pitch (frequency theory): that the frequency of neural impulses traveling up the auditory nerve correspond to the frequency of a tone. See) place theory of pitch.

test battery:

test profile: chart plotting scores from a number of tests given to the same individual (or group of individuals) in parallel rows on a common scale, with the scores connected by lines, so that high and low scores can be readily perceived.

test-retest reliability (temporal stability): consistency test results when the same person is tested over successive occasions. See) reliability.

testosterone: kind of androgen that is responsible during puberty for the sudden growth of facial, underarm, or pubic hair; it also causes a deepening of the voice, the development of muscles that lead to a more masculine form, and the growth of the external genitals.

texture gradient: Depth Perception) one cue for perceiving depth directly. When viewing a surface in perspective, the elements that make up the surface appear to be packed closer and closer together, giving an impression of depth. See) distance cues.

thalamus: two groups of nerve cell nuclei located just above the brain stem and inside the cerebral hemispheres. Considered a part of the central core of the brain. One area acts as a sensory relay station, the other plays a role in sleep and waking; this portion is considered part of the limbic system. See) hypothalamus.

theory: set of assumptions advanced to explain existing data and predict new events; usually applicable to a wide array of phenomena.

theta rhythm: See electroencephalogram.

thinking: ability to imagine or represent objects or events in memory and to operate on these representations.

three primaries law: Color Vision) basic law that three wavelengths of light can be combined to match almost any color of light, if one light is drawn from the long-wave end of the spectrum, another from the middle, and the third light from the short end.

threshold: transitional point at which an increasing stimulus or an increasing difference not previously perceived becomes perceptible (or at which a decreasing stimulus or previously perceived difference becomes imperceptible). The value obtained depends in part on the methods used in determining it. See) absolute threshold, difference threshold.

thyroid gland: endocrine gland located in the neck, whose hormone thyroxin is important in determining metabolic rate.

timbre: Audition) quality distinguishing a tone of the same pitch sounded by different instruments, due to overtonesovertones and other so-called "impurities".

tip-of-the-tongue phenomenon: experience of failing to recall a word or a name when quite certain that it is known.

tolerance: Drug Dependence) the need to take more and more of a drug to achieve the same effect.

tonic pain: steady, long-lasting pain experienced after an injury; usually produced by swelling and tissue damage. In contrast to phasic pain.

top-down processes: processes driven by prior knowledge and expectations, rather than by the input; involved in perception, learning, memory, and comprehension. See) bottom-up processes.

topographic model: Freud's model of the human mind, containing the conscious, preconscious, and the unconscious. See) conscious, preconscious, unconscious.

trace conditioning: Classical Conditioning) procedure in which the conditioned stimulus terminates before the onset of the unconditioned stimulus. See) delayed conditioning.

tranquilizer: drug that reduces anxiety and agitation. See antianxiety drug.

transducer: psychophysiology) device such as an electrode or gauge that converts physiological indicators into other forms of energy that can be recorded and measured.

transduction: The translation of a physical energy into electrical signals by specialized receptor cells.

transference: Psychoanalysis) a patient unconsciously making the therapist the object of emotional response, transferring to the therapist responses appropriate to other persons important in the patient's life history.

transsexual: one who is physically one sex but psychologically the other. Transsexuals sometimes resort to surgery and hormonal treatment to change their physical appearance. They do not, however, consider themselves to be homosexual. See) homosexual.

trichromatic theory (Young-Helmholtz theory): Color Vision) postulates three basic color receptors (cones), a red receptor, a green receptor, and a blue receptor; explains color blindness by the absence of one or more receptor types. See) opponent-color theory, two-stage color theory.

trichromatism: Color Vision) based on the classification of color vision according to three color systems: black-white, blue-yellow, and red-green; the normal eye sees all three; the colorblind eye is defective in one or two of the three systems. See) dichromatism, monochromatism.

tricyclic antidepressant: class of antidepressants that relieve the symptoms of depression by preventing the reuptake of the neurotransmitters serotonin and norepinephrine, thereby prolonging their action. Imipramine (brand names, Tofranil and Elavil) is one drug commonly prescribed.

two-point threshold: minimum distance by which two thin rods touching the skin must be separated before they are felt as two points rather than one; kind of pressure threshold.

two-stage color theory: Color Vision) that in a first stage light is received by three types of cones (in agreement with trichromatic theory) and in the second stage the outputs are interconnected to form red-green, yellow-blue and white-black channels (in agreement with opponent-color theory). This theory accounts for much of what is known about color vision, and serves as a prototype for the analysis of other sensory systems.

type A behavior (type A personality): rushed, competitive, aggressive, and overcommitted to achieving, and higher risk for heart disease; one of two (type A and type B) contrasting behavior patterns found in studies of coronary heart disease.

type B behavior (type A personality): relaxed, feeling little pressure and at lower risk for heart disease; one of two (type A and type B) contrasting behavior patterns found in studies of coronary heart disease.

unconditioned response (UCR): Classical Conditioning) response given originally to the unconditioned stimulus used as the basis for establishing a conditioned response to a previously neutral stimulus.

unconditioned stimulus (UCS): Classical Conditioning) a stimulus that automatically elicits a response, typically via a reflex, without prior conditioning. See) conditioned response, conditioned stimulus, unconditioned response.

unconscious: Freud's Topographic Model) part of the mind containing repressed thoughts and memories of which the individual is unaware. See) conscious, preconscious

unconscious inference: Hermann von Helmholtz) process by which the perceiver progresses from experiencing sensations evoked by an object to recognizing the properties of the object. We make this inference automatically and unconsciously, and eventually we do not even notice the sensations on which it is based. Helmholtz argued that this is the basis of many perceptual phenomena, including distance and object perception.

unconscious motive: motive of which the subject is unaware or aware of in distorted form. Many motives have both conscious and unconscious aspects. There is no sharp dividing line between conscious and unconscious.

unconscious processes: memories, impulses, and desires that are not available to consciousness. Sigmund Freud's psychoanalytic theories) painful memories and wishes are sometimes repressed, that is, diverted to the unconscious where they continue to influence our actions even though we are not aware of them.

validity: predictive significance of a test for its intended purposes. Validity can be measured by a coefficient of correlation between scores on the test and the scores that the test seeks to predict, in other words, scores on some criterion. See) criterion, reliability.

validity coefficient: correlation between a test score and some criterion to which the test is supposed to predict. See) criterion, validity.

variable: one of the conditions measured in an experiment, which can be controlled or uncontrolled. See) dependent variable, independent variable.

variance: square of a standard deviation.

ventromedial hypothalamus (VMH): area of the hypothalamus important to the regulation of food intake. Electrical stimulation of this area will make an experimental animal stop eating; destruction of brain tissue here produces voracious eating, eventually leading to obesity. See) lateral hypothalamus.

vestibular apparatus: organ containing receptors for body movement and kinesthesis.

vestibular sacs (otoliths): Inner Ear) two sacs in the labyrinth, called the saccule and utricle, which contain the otoliths (ear stones). Pressure of the otoliths on the hair cells in the gelatinous material of the utricle and saccule gives us the sense of body tilt or linear acceleration. See) equilibratory senses.

vicarious learning (observational learning): by observing the behavior of others and noting the consequences of that behavior.

visual acuity: ability to detect visual detail.

visual area: Brain) projection area lying in the occipital lobe; damage to this area produces blindness in portions of the visual field of humans corresponding to the amount and location of the damage.

visual buffer: Short-term Memory) hypothesized component of the encoding process that briefly stores information in a visual code (a visual representation of verbal and nonverbal items). See) acoustic buffer, central executive.

visual cliff: experimental apparatus used to test the depth perception of animals and human infants; a glass over a patterned surface, one half of which is just below the glass and the other half, several feet below.

visual cortex:

visual field: total visual array acting on the eye when it is directed toward a fixation point.

visual-evoked potentials: method of studying perception using electrodes placed on the back of the head over the visual cortex. The electrodes record electrical responses related to how well the observer can discriminate a presented stimulus.

visual resolution:

volumetric receptors: hypothesized receptors that regulate water intake by responding to the volume of blood and body fluids. Renin, a substance secreted by the kidneys into the bloodstream, may be one volumetric receptor; it constricts the blood vessels and stimulates the release of the hormone, angiotensin, which acts on cells in the hypothalamus to produce thirst. See) osmoreceptors.

voluntary processes: activities selected by choice and controlled or monitored according to intention or plan. See) control processes.

vulnerability-stress model (diathesis-stress model): interactive model of physical or mental disorders that proposes that an individual will develop a disorder only when having both some constitutional vulnerability (predisposition) and stressful circumstances. Same as .

weak methods: general problem-solving strategies that do not depend on specific knowledge of a problem. Examples are difference reduction, means-ends analysis, and working backwards.

Weber's law (& Weber's constant): the difference threshold is a fixed proportion of the stimulus magnitude at which it is measured. The proportion is constant over a wide range of stimulus magnitudes, and is called Weber's constant. The value of Weber's constant depends on the sensory modality; the smaller the constant, the more sensitive the modality.

Wernicke's area: portion of the left cerebral hemisphere involved in language understanding. Individuals with damage in this area can hear words, but cannot comprehend the meanings of the words.

withdrawal symptoms: unpleasant physiological and psychological reactions that occur when a person suddenly stops taking an addictive drug; these range from nausea, anxiety, mild tremors, and difficulty sleeping at low levels of dependence to vomiting, cramps, hallucinations, agitation, and severe tremors or seizures at higher levels. See) drug dependence.

working backwards: problem-solving strategy in which one works backwards from the goal towards the current state. See) difference reduction, means-ends analysis.

working through: Psychoanalytic Therapy) process of reeducation by having one face the same conflicts over and over in the consultation room, until one can independently face and master the conflicts of ordinary life.

X chromosome: chromosome that, combined with another X chromosome, determines the female gender or combined with a Y chromosome, the male; chromosome that transmits sex-linked traits.

XYY syndrome: abnormal condition in which a male has an extra Y chromosome; reputedly associated with unusual aggressiveness, although the evidence is not conclusive. See) Y chromosome.

Y chromosome: The chromosome that, combined with an X chromosome, determines maleness. See) chromosome, sex-linked trait, X chromosome.

zygote: fertilized ovum or egg. See) dizygotic twins, monozygotic twins.

Glossary, Seeing, Hearing and Smelling the World:   Howard Hughes Medical Institute

Glossary of Terms:   Brains on the Web: Comparative Neuroanatomy and Intelligence -