Glossary

G-1

absolute threshold the minimum stimulus energy needed to detect a particular stimulus 50 percent of the time. (p. 231)

accommodation (1) in developmental psychology, adapting our current understandings (schemas) to incorporate new information. (2) in sensation and perception, the process by which the eye’s lens changes shape to focus near or far objects on the retina. (p. 187, 240)

achievement motivation a desire for significant accomplishment; for mastery of skills or ideas; for control; and for attaining a high standard. (p. 454)

achievement test a test designed to assess what a person has learned. (p. 392)

acquisition in classical conditioning, the initial stage, when one links a neutral stimulus and an unconditioned stimulus so that the neutral stimulus begins triggering the conditioned response. In operant conditioning, the strengthening of a reinforced response. (p. 284)

action potential a neural impulse; a brief electrical charge that travels down an axon. (p. 54)

active listening empathic listening in which the listener echoes, restates, and clarifies. A feature of Rogers’ client-centered therapy. (p. 661)

acute schizophrenia (also called reactive schizophrenia) a form of schizophrenia that can begin at any age, frequently occurs in response to an emotionally traumatic event, and has extended recovery periods. (p. 641)

adaptation-level phenomenon our tendency to form judgments (of sounds, of lights, of income) relative to a neutral level defined by our prior experience. (p. 483)

addiction compulsive craving of drugs or certain behaviors (such as gambling) despite known adverse consequences. (p. 118)

adolescence the transition period from childhood to adulthood, extending from puberty to independence. (p. 203)

adrenal [ah-DREEN-el] glands a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress. (p. 64)

aerobic exercise sustained exercise that increases heart and lung fitness; may also alleviate depression and anxiety. (p. 508)

affiliation need the need to build relationships and to feel part of a group. (p. 448)

aggression any physical or verbal behavior intended to harm someone physically or emotionally. (pp. 162, 545)

agonist a molecule that increases a neurotransmitter’s action. (p. 59)

AIDS (acquired immune deficiency syndrome) a life-threatening, sexually transmitted infection caused by the human immunodeficiency virus (HIV). AIDS depletes the immune system, leaving the person vulnerable to infections. (p. 436)

alcohol use disorder (popularly known as alcoholism) alcohol use marked by tolerance, withdrawal, and a drive to continue problematic use. (p. 120)

algorithm a methodical, logical rule or procedure that guarantees solving a particular problem. Contrasts with the usually speedier—but also more error-prone—use of heuristics. (p. 357)

all-or-none response a neuron’s reaction of either firing (with a full-strength response) or not firing. (p. 55)

alpha waves the relatively slow brain waves of a relaxed, awake state. (p. 102)

altruism unselfish regard for the welfare of others. (p. 558)

Alzheimer’s disease a neurocognitive disorder marked by neural plaques, often with an onset after age 80, and entailing a progressive decline in memory and other cognitive abilities. (p. 218)

amphetamines drugs that stimulate neural activity, causing speeded-up body functions and associated energy and mood changes. (p. 121)

amygdala [uh-MIG-duh-la] two lima-bean-sized neural clusters in the limbic system; linked to emotion. (p. 71)

androgyny displaying both traditional masculine and feminine psychological characteristics. (p. 169)

anorexia nervosa an eating disorder in which a person (usually an adolescent female) maintains a starvation diet despite being significantly underweight; sometimes accompanied by excessive exercise. (p. 651)

antagonist a molecule that inhibits or blocks a neurotransmitter’s action. (p. 59)

anterograde amnesia an inability to form new memories. (p. 338)

antianxiety drugs drugs used to control anxiety and agitation. (p. 682)

antidepressant drugs drugs used to treat depression, anxiety disorders, obsessive-compulsive disorder, and posttraumatic stress disorder. (Several widely used antidepressant drugs are selective serotonin reuptake inhibitors—SSRIs.) (p. 683)

antipsychotic drugs drugs used to treat schizophrenia and other forms of severe thought disorder. (p. 682)

antisocial personality disorder a personality disorder in which a person (usually a man) exhibits a lack of conscience for wrongdoing, even toward friends and family members; may be aggressive and ruthless or a clever con artist. (p. 649)

anxiety disorders psychological disorders characterized by distressing, persistent anxiety or maladaptive behaviors that reduce anxiety. (p. 620)

aphasia impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding). (p. 376)

applied research scientific study that aims to solve practical problems. (p. 12)

aptitude test a test designed to predict a person’s future performance; aptitude is the capacity to learn. (p. 392)

asexual having no sexual attraction to others. (p. 433)

assimilation interpreting our new experiences in terms of our existing schemas. (p. 187)

association areas areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking. (p. 79)

associative learning learning that certain events occur together. The events may be two stimuli (as in classical conditioning) or a response and its consequences (as in operant conditioning). (pp. 280, 290)

G-2

attachment an emotional tie with another person; shown in young children by their seeking closeness to the caregiver and showing distress on separation. (p. 195)

attention-deficit/hyperactivity disorder (ADHD) a psychological disorder marked by extreme inattention and/or hyperactivity and impulsivity. (p. 615)

attitude feelings, often influenced by our beliefs, that predispose us to respond in a particular way to objects, people, and events. (p. 520)

attribution theory the theory that we explain someone’s behavior by crediting either the situation or the person’s disposition. (p. 518)

audition the sense or act of hearing. (p. 256)

autism spectrum disorder (ASD) a disorder that appears in childhood and is marked by significant deficiencies in communication and social interaction, and by rigidly fixated interests and repetitive behaviors. (p. 192)

automatic processing unconscious encoding of incidental information, such as space, time, and frequency, and of well-learned information, such as word meanings. (p. 321)

autonomic [aw-tuh-NAHM-ik] nervous system (ANS) the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms. (p. 60)

availability heuristic estimating the likelihood of events based on their availability in memory; if instances come readily to mind (perhaps because of their vividness), we presume such events are common. (p. 359)

aversive conditioning a type of counterconditioning that associates an unpleasant state (such as nausea) with an unwanted behavior (such as drinking alcohol). (p. 665)

axon the neuron extension that passes messages through its branches to other neurons or to muscles or glands. (p. 53)

babbling stage beginning at about 4 months, the stage of speech development in which the infant spontaneously utters various sounds at first unrelated to the household language. (p. 372)

barbiturates drugs that depress central nervous system activity, reducing anxiety but impairing memory and judgment. (p. 120)

basal metabolic rate the body’s resting rate of energy expenditure. (p. 427)

basic research pure science that aims to increase the scientific knowledge base. (p. 11)

basic trust according to Erik Erikson, a sense that the world is predictable and trustworthy; said to be formed during infancy by appropriate experiences with responsive caregivers. (p. 199)

behavior feedback effect the tendency of behavior to influence our own and others’ thoughts, feelings, and actions. (p. 474)

behavior genetics the study of the relative power and limits of genetic and environmental influences on behavior. (pp. 7, 134)

behavior therapy therapy that applies learning principles to the elimination of unwanted behaviors. (p. 663)

behaviorism the view that psychology (1) should be an objective science that (2) studies behavior without reference to mental processes. Most research psychologists today agree with (1) but not with (2). (pp. 4, 282)

belief perseverance clinging to one’s initial conceptions after the basis on which they were formed has been discredited. (p. 361)

binge-eating disorder significant binge-eating episodes, followed by distress, disgust, or guilt, but without the compensatory purging or fasting that marks bulimia nervosa. (p. 652)

binocular cues depth cues, such as retinal disparity, that depend on the use of two eyes. (p. 249)

biological perspective concerned with the links between biology and behavior. Includes psychologists working in neuroscience, behavior genetics, and evolutionary psychology. These researchers may call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists. (p. 52)

biomedical therapy prescribed medications or procedures that act directly on the person’s physiology. (pp. 658, 681)

biopsychosocial approach an integrated approach that incorporates biological, psychological, and social-cultural levels of analysis. (p. 9)

bipolar disorder a disorder in which a person alternates between the hopelessness and lethargy of depression and the overexcited state of mania. (Formerly called manic-depressive disorder.) (p. 629)

blind spot the point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there. (p. 241)

blindsight a condition in which a person can respond to a visual stimulus without consciously experiencing it. (p. 94)

bottom-up processing analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information. (p. 230)

brainstem the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions. (p. 69)

Broca’s area controls language expression—an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech. (p. 376)

bulimia nervosa an eating disorder in which a person alternates binge eating (usually of high-calorie foods) with purging (by vomiting or laxative use) or fasting. (p. 651)

bystander effect the tendency for any given bystander to be less likely to give aid if other bystanders are present. (p. 560)

Cannon-Bard theory the theory that an emotion-arousing stimulus simultaneously triggers (1) physiological responses and (2) the subjective experience of emotion. (p. 460)

case study a descriptive technique in which one individual or group is studied in depth in the hope of revealing universal principles. (p. 28)

catharsis emotional release. In psychology, the catharsis hypothesis maintains that “releasing” aggressive energy (through action or fantasy) relieves aggressive urges. (p. 477)

central nervous system (CNS) the brain and spinal cord. (p. 60)

central route persuasion occurs when interested people focus on the arguments and respond with favorable thoughts. (p. 520)

cerebellum [sehr-uh-BELL-um] the “little brain” at the rear of the brainstem; functions include processing sensory input, coordinating movement output and balance, and enabling nonverbal learning and memory. (p. 70)

cerebral [seh-REE-bruhl] cortex the intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center. (p. 74)

G-3

change blindness failing to notice changes in the environment. (p. 98)

chromosomes threadlike structures made of DNA molecules that contain the genes. (p. 134)

chronic schizophrenia (also called process schizophrenia) a form of schizophrenia in which symptoms usually appear by late adolescence or early adulthood. As people age, psychotic episodes last longer and recovery periods shorten. (p. 641)

chunking organizing items into familiar, manageable units; often occurs automatically. (p. 324)

circadian [ser-KAY-dee-an] rhythm the biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle. (p. 100)

classical conditioning a type of learning in which one learns to link two or more stimuli and anticipate events. (p. 282)

client-centered therapy a humanistic therapy, developed by Carl Rogers, in which the therapist uses techniques such as active listening within a genuine, accepting, empathic environment to facilitate clients’ growth. (Also called person-centered therapy.) (p. 661)

clinical psychology a branch of psychology that studies, assesses, and treats people with psychological disorders. (p. 12)

cocaine a powerful and addictive stimulant derived from the coca plant; produces temporarily increased alertness and euphoria. (p. 123)

cochlea [KOHK-lee-uh] a coiled, bony, fluid-filled tube in the inner ear; sound waves traveling through the cochlear fluid trigger nerve impulses. (p. 257)

cochlear implant a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea. (p. 259)

cognition all the mental activities associated with thinking, knowing, remembering, and communicating. (pp. 186, 356)

cognitive-behavioral therapy (CBT) a popular integrative therapy that combines cognitive therapy (changing self-defeating thinking) with behavior therapy (changing behavior). (p. 669)

cognitive dissonance theory the theory that we act to reduce the discomfort (dissonance) we feel when two of our thoughts (cognitions) are inconsistent. For example, when we become aware that our attitudes and our actions clash, we can reduce the resulting dissonance by changing our attitudes. (pp. 523, 529)

cognitive learning the acquisition of mental information, whether by observing events, by watching others, or through language. (pp. 282, 304)

cognitive map a mental representation of the layout of one’s environment. For example, after exploring a maze, rats act as if they have learned a cognitive map of it. (p. 305)

cognitive neuroscience the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language). (pp. 5, 93)

cognitive therapy therapy that teaches people new, more adaptive ways of thinking; based on the assumption that thoughts intervene between events and our emotional reactions. (p. 667)

cohort a group of people sharing a common characteristic, such as from a given time period. (p. 400)

collective unconscious Carl Jung’s concept of a shared, inherited reservoir of memory traces from our species’ history. (p. 577)

collectivism giving priority to the goals of one’s group (often one’s extended family or work group) and defining one’s identity accordingly. (p. 157)

color constancy perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the objects. (p. 251)

community psychology a branch of psychology that studies how people interact with their social environments and how social institutions affect individuals and groups. (p. 12)

companionate love the deep affectionate attachment we feel for those with whom our lives are intertwined. (p. 557)

concept a mental grouping of similar objects, events, ideas, or people. (p. 356)

concrete operational stage in Piaget’s theory, the stage of cognitive development (from about 7 to 11 years of age) during which children gain the mental operations that enable them to think logically about concrete events. (p. 190)

conditioned reinforcer a stimulus that gains its reinforcing power through its association with a primary reinforcer; also known as a secondary reinforcer. (p. 292)

conditioned response (CR) in classical conditioning, a learned response to a previously neutral (but now conditioned) stimulus (CS). (p. 284)

conditioned stimulus (CS) in classical conditioning, an originally irrelevant stimulus that, after association with an unconditioned stimulus (US), comes to trigger a conditioned response (CR). (p. 284)

conduction hearing loss less common form of hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea. (p. 257)

cones retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. The cones detect fine detail and give rise to color sensations. (p. 241)

confirmation bias a tendency to search for information that supports our preconceptions and to ignore or distort contradictory evidence. (p. 357)

conflict a perceived incompatibility of actions, goals, or ideas. (p. 562)

conformity adjusting our behavior or thinking to coincide with a group standard. (p. 526)

confounding variable in an experiment, a factor other than the independent variable that might produce an effect. (p. 37)

consciousness our awareness of ourselves and our environment. (p. 92)

conservation the principle (which Piaget believed to be a part of concrete operational reasoning) that properties such as mass, volume, and number remain the same despite changes in the forms of objects. (p. 189)

content validity the extent to which a test samples the behavior that is of interest. (p. 397)

continuous reinforcement schedule reinforcing the desired response every time it occurs. (p. 293)

control group in an experiment, the group not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment. (p. 35)

convergent thinking narrowing the available problem solutions to determine the single best solution. (p. 366)

G-4

coping alleviating stress using emotional, cognitive, or behavioral methods. (p. 500)

coronary heart disease the clogging of the vessels that nourish the heart muscle; the leading cause of death in many developed countries. (p. 496)

corpus callosum [KOR-pus kah-LOW-sum] the large band of neural fibers connecting the two brain hemispheres and carrying messages between them. (p. 82)

correlation a measure of the extent to which two factors vary together, and thus of how well either factor predicts the other. (p. 32)

correlation coefficient a statistical index of the relationship between two things (from −1.00 to +1.00). (p. 32)

counseling psychology a branch of psychology that assists people with problems in living (often related to school, work, or marriage) and in achieving greater well-being. (p. 12)

counterconditioning behavior therapy procedures that use classical conditioning to evoke new responses to stimuli that are triggering unwanted behaviors; include exposure therapies and aversive conditioning. (p. 663)

creativity the ability to produce new and valuable ideas. (p. 365)

critical period an optimal period early in the life of an organism when exposure to certain stimuli or experiences produces normal development. (p. 196)

critical thinking thinking that does not blindly accept arguments and conclusions. Rather, it examines assumptions, appraises the source, discerns hidden values, evaluates evidence, and assesses conclusions. (p. 24)

cross-sectional study a study in which people of different ages are compared with one another. (p. 218)

crystallized intelligence our accumulated knowledge and verbal skills; tends to increase with age. (p. 400)

culture the enduring behaviors, ideas, attitudes, values, and traditions shared by a group of people and transmitted from one generation to the next. (pp. 7, 155)

debriefing the postexperimental explanation of a study, including its purpose and any deceptions, to its participants. (p. 41)

deep processing encoding semantically, based on the meaning of the words; tends to yield the best retention. (p. 326)

defense mechanisms in psychoanalytic theory, the ego’s protective methods of reducing anxiety by unconsciously distorting reality. (p. 575)

deindividuation the loss of self-awareness and self-restraint occurring in group situations that foster arousal and anonymity. (p. 533)

déjà vu that eerie sense that “I’ve experienced this before.” Cues from the current situation may unconsciously trigger retrieval of an earlier experience. (p. 346)

delta waves the large, slow brain waves associated with deep sleep. (p. 102)

delusion a false belief, often of persecution or grandeur, that may accompany psychotic disorders. (p. 640)

dendrites a neuron’s bushy, branching extensions that receive messages and conduct impulses toward the cell body. (p. 53)

dependent variable in an experiment, the outcome that is measured; the variable that may change when the independent variable is manipulated. (p. 37)

depressants drugs (such as alcohol, barbiturates, and opiates) that reduce neural activity and slow body functions. (p. 119)

depth perception the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance. (p. 249)

developmental psychology a branch of psychology that studies physical, cognitive, and social change throughout the life span. (p. 178)

difference threshold the minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference (or jnd). (p. 232)

discrimination (1) in classical conditioning, the learned ability to distinguish between a conditioned stimulus and stimuli that do not signal an unconditioned stimulus. (2) in social psychology, unjustifiable negative behavior toward a group and its members. (pp. 267, 538)

disorder of sexual development an inherited condition that involves unusual development of sex chromosomes and anatomy. (p. 167)

dissociation a split in consciousness, which allows some thoughts and behaviors to occur simultaneously with others. (p. 265)

dissociative disorders controversial, rare disorders in which conscious awareness becomes separated (dissociated) from previous memories, thoughts, and feelings. (p. 646)

dissociative identity disorder (DID) a rare dissociative disorder in which a person exhibits two or more distinct and alternating personalities. Formerly called multiple personality disorder. (p. 647)

divergent thinking expanding the number of possible problem solutions; creative thinking that diverges in different directions. (p. 366)

DNA (deoxyribonucleic acid) a complex molecule containing the genetic information that makes up the chromosomes. (p. 134)

double-blind procedure an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Commonly used in drug-evaluation studies. (p. 36)

Down syndrome a condition of mild to severe intellectual disability and associated physical disorders caused by an extra copy of chromosome 21. (p. 403)

dream a sequence of images, emotions, and thoughts passing through a sleeping person’s mind. Dreams are notable for their hallucinatory imagery, discontinuities and incongruities, and for the dreamer’s delusional acceptance of the content and later difficulties remembering it. (p. 112)

drive-reduction theory the idea that a physiological need creates an aroused tension state (a drive) that motivates an organism to satisfy the need. (p. 421)

DSM-5 the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition; a widely used system for classifying psychological disorders. (p. 613)

dual processing the principle that information is often simultaneously processed on separate conscious and unconscious tracks. (p. 94)

G-5

echoic memory a momentary sensory memory of auditory stimuli; if attention is elsewhere, sounds and words can still be recalled within 3 or 4 seconds. (p. 323)

eclectic approach an approach to psychotherapy that uses techniques from various forms of therapy. (p. 658)

Ecstasy (MDMA) a synthetic stimulant and mild hallucinogen. Produces euphoria and social intimacy, but with short-term health risks and longer-term harm to serotonin-producing neurons and to mood and cognition. (p. 124)

effortful processing encoding that requires attention and conscious effort. (p. 321)

ego the largely conscious, “executive” part of personality that, according to Freud, mediates among the demands of the id, superego, and reality. The ego operates on the reality principle, satisfying the id’s desires in ways that will realistically bring pleasure rather than pain. (p. 574)

egocentrism in Piaget’s theory, the preoperational child’s difficulty taking another’s point of view. (p. 189)

electroconvulsive therapy (ECT) a biomedical therapy for severely depressed patients in which a brief electric current is sent through the brain of an anesthetized patient. (p. 685)

electroencephalogram (EEG) an amplified recording of the waves of electrical activity sweeping across the brain’s surface. These waves are measured by electrodes placed on the scalp. (p. 67)

embodied cognition in psychological science, the influence of bodily sensations, gestures, and other states on cognitive preferences and judgments. (p. 271)

embryo the developing human organism from about 2 weeks after fertilization through the second month. (p. 181)

emerging adulthood a period from about age 18 to the mid-twenties, when many in Western cultures are no longer adolescents but have not yet achieved full independence as adults. (p. 212)

emotion a response of the whole organism, involving (1) physiological arousal, (2) expressive behaviors, and (3) conscious experience. (p. 460)

emotion-focused coping attempting to alleviate stress by avoiding or ignoring a stressor and attending to emotional needs related to our stress reaction. (p. 500)

emotional intelligence the ability to perceive, understand, manage, and use emotions. (p. 390)

empirically derived test a test (such as the MMPI) developed by testing a pool of items and then selecting those that discriminate between groups. (p. 589)

encoding the processing of information into the memory system—for example, by extracting meaning. (p. 320)

encoding specificity principle the idea that cues and contexts specific to a particular memory will be most effective in helping us recall it. (p. 335)

endocrine [EN-duh-krin] system the body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream. (p. 63)

endorphins [en-DOR-fins] “morphine within”—natural, opiate-like neurotransmitters linked to pain control and to pleasure. (p. 58)

environment every nongenetic influence, from prenatal nutrition to the people and things around us. (p. 134)

epigenetics the study of environmental influences on gene expression that occur without a DNA change. (pp. 143, 612)

equity a condition in which people receive from a relationship in proportion to what they give to it. (p. 557)

erectile disorder inability to develop or maintain an erection due to insufficient bloodflow to the penis. (p. 435)

estrogens sex hormones, such as estradiol, secreted in greater amounts by females than by males and contributing to female sex characteristics. In nonhuman female mammals, estrogen levels peak during ovulation, promoting sexual receptivity. (p. 433)

evidence-based practice clinical decision making that integrates the best available research with clinical expertise and patient characteristics and preferences. (p. 676)

evolutionary psychology the study of the evolution of behavior and the mind, using principles of natural selection. (pp. 7, 144)

experiment a research method in which an investigator manipulates one or more factors (independent variables) to observe the effect on some behavior or mental process (the dependent variable). By random assignment of participants, the experimenter aims to control other relevant factors. (p. 35)

experimental group in an experiment, the group exposed to the treatment, that is, to one version of the independent variable. (p. 35)

explicit memory memory of facts and experiences that one can consciously know and “declare.” (Also called declarative memory.) (pp. 321, 329)

exposure therapies behavioral techniques, such as systematic desensitization and virtual reality exposure therapy, that treat anxieties by exposing people (in imagination or actual situations) to the things they fear and avoid. (p. 664)

external locus of control the perception that chance or outside forces beyond our personal control determine our fate. (p. 503)

extinction the diminishing of a conditioned response; occurs in classical conditioning when an unconditioned stimulus (US) does not follow a conditioned stimulus (CS); occurs in operant conditioning when a response is no longer reinforced. (p. 285)

extrasensory perception (ESP) the controversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition. (p. 272)

extrinsic motivation a desire to perform a behavior to receive promised rewards or avoid threatened punishment. (p. 305)

facial feedback effect the tendency of facial muscle states to trigger corresponding feelings such as fear, anger, or happiness. (p. 474)

family therapy therapy that treats the family as a system. Views an individual’s unwanted behaviors as influenced by, or directed at, other family members. (p. 670)

feature detectors nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement. (p. 245)

feel-good, do-good phenomenon people’s tendency to be helpful when already in a good mood. (p. 479)

female orgasmic disorder distress due to infrequently or never experiencing orgasm. (p. 435)

fetal alcohol syndrome (FAS) physical and cognitive abnormalities in children caused by a pregnant woman’s heavy drinking. In severe cases, signs include a small, out-of-proportion head and abnormal facial features. (p. 182)

fetus the developing human organism from 9 weeks after conception to birth. (p. 181)

G-6

figure-ground the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground). (p. 248)

fixation according to Freud, a lingering focus of pleasure-seeking energies at an earlier psychosexual stage, in which conflicts were unresolved. (p. 575)

fixed-interval schedule in operant conditioning, a reinforcement schedule that reinforces a response only after a specified time has elapsed. (p. 294)

fixed-ratio schedule in operant conditioning, a reinforcement schedule that reinforces a response only after a specified number of responses. (p. 294)

flashbulb memory a clear memory of an emotionally significant moment or event. (p. 331)

flow a completely involved, focused state of consciousness, with diminished awareness of self and time, resulting from optimal engagement of one’s skills. (p. A-1)

fluid intelligence our ability to reason speedily and abstractly; tends to decrease during late adulthood. (p. 400)

fMRI (functional MRI) a technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function as well as structure. (p. 68)

foot-in-the-door phenomenon the tendency for people who have first agreed to a small request to comply later with a larger request. (p. 521)

formal operational stage in Piaget’s theory, the stage of cognitive development (normally beginning about age 12) during which people begin to think logically about abstract concepts. (p. 191)

fovea the central focal point in the retina, around which the eye’s cones cluster. (p. 242)

framing the way an issue is posed; how an issue is framed can significantly affect decisions and judgments. (p. 362)

fraternal twins (dizygotic twins) develop from separate fertilized eggs. They are genetically no closer than ordinary brothers and sisters, but they share a prenatal environment. (p. 136)

free association in psychoanalysis, a method of exploring the unconscious in which the person relaxes and says whatever comes to mind, no matter how trivial or embarrassing. (p. 573)

frequency the number of complete wavelengths that pass a point in a given time (for example, per second). (p. 256)

frequency theory in hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch. (Also called temporal theory.) (p. 260)

frontal lobes portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgments. (p. 75)

frustration-aggression principle the principle that frustration—the blocking of an attempt to achieve some goal—creates anger, which can generate aggression. (p. 547)

functionalism early school of thought promoted by James and influenced by Darwin; explored how mental and behavioral processes function—how they enable the organism to adapt, survive, and flourish. (p. 3)

fundamental attribution error the tendency for observers, when analyzing others’ behavior, to underestimate the impact of the situation and to overestimate the impact of personal disposition. (p. 518)

gate-control theory the theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain. The “gate” is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain. (p. 262)

gender in psychology, the socially influenced characteristics by which people define men and women. (p. 161)

gender identity our sense of being male, female, or a combination of the two. (p. 168)

gender role a set of expected behaviors, attitudes, and traits for males or for females. (p. 167)

gender typing the acquisition of a traditional masculine or feminine role. (p. 168)

general adaptation syndrome (GAS) Selye’s concept of the body’s adaptive response to stress in three phases—alarm, resistance, exhaustion. (p. 491)

general intelligence (g) a general intelligence factor that, according to Spearman and others, underlies specific mental abilities and is therefore measured by every task on an intelligence test. (p. 386)

generalization the tendency, once a response has been conditioned, for stimuli similar to the conditioned stimulus to elicit similar responses. (p. 286)

generalized anxiety disorder an anxiety disorder in which a person is continually tense, apprehensive, and in a state of autonomic nervous system arousal. (p. 620)

genes the biochemical units of heredity that make up the chromosomes; segments of DNA capable of synthesizing proteins. (p. 134)

genome the complete instructions for making an organism, consisting of all the genetic material in that organism’s chromosomes. (p. 135)

gestalt an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes. (p. 247)

glial cells (glia) cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory. (p. 54)

glucose the form of sugar that circulates in the blood and provides the major source of energy for body tissues. When its level is low, we feel hunger. (p. 426)

grammar in a language, a system of rules that enables us to communicate with and understand others. In a given language, semantics is the set of rules for deriving meaning from sounds, and syntax is the set of rules for combining words into grammatically sensible sentences. (p. 371)

GRIT Graduated and Reciprocated Initiatives in Tension-Reduction—a strategy designed to decrease international tensions. (p. 567)

grit in psychology, passion and perseverance in the pursuit of long-term goals. (p. 455)

grouping the perceptual tendency to organize stimuli into coherent groups. (p. 248)

group polarization the enhancement of a group’s prevailing inclinations through discussion within the group. (p. 534)

G-7

group therapy therapy conducted with groups rather than individuals, permitting therapeutic benefits from group interaction. (p. 670)

groupthink the mode of thinking that occurs when the desire for harmony in a decision-making group overrides a realistic appraisal of alternatives. (p. 535)

habituation decreasing responsiveness with repeated stimulation. As infants gain familiarity with repeated exposure to a stimulus, their interest wanes and they look away sooner. (p. 183)

hallucinations false sensory experiences, such as seeing something in the absence of an external visual stimulus. (p. 102)

hallucinogens psychedelic (“mind-manifesting”) drugs, such as LSD, that distort perceptions and evoke sensory images in the absence of sensory input. (p. 124)

health psychology a subfield of psychology that provides psychology’s contribution to behavioral medicine. (p. 492)

heritability the proportion of variation among individuals that we can attribute to genes. The heritability of a trait may vary, depending on the range of populations and environments studied. (pp. 140, 406)

heuristic a simple thinking strategy that often allows us to make judgments and solve problems efficiently; usually speedier but also more error-prone than algorithms. (p. 357)

hierarchy of needs Maslow’s pyramid of human needs, beginning at the base with physiological needs that must first be satisfied before higher-level safety needs and then psychological needs become active. (p. 422)

higher-order conditioning a procedure in which the conditioned stimulus in one conditioning experience is paired with a new neutral stimulus, creating a second (often weaker) conditioned stimulus. For example, an animal that has learned that a tone predicts food might then learn that a light predicts the tone and begin responding to the light alone. (Also called second-order conditioning.) (p. 285)

hindsight bias the tendency to believe, after learning an outcome, that one would have foreseen it. (Also known as the I-knew-it-all-along phenomenon.) (p. 20)

hippocampus a neural center located in the limbic system; helps process explicit memories for storage. (pp. 71, 329)

homeostasis a tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level. (p. 421)

hormones chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues. (p. 63)

hue the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth. (p. 239)

human factors psychology an I/O psychology subfield that explores how people and machines interact and how machines and physical environments can be made safe and easy to use. (p. A-2)

humanistic psychology historically significant perspective that emphasized human growth potential. (p. 5)

humanistic theories view personality with a focus on the potential for healthy personal growth. (p. 583)

hypnosis a social interaction in which one person (the hypnotist) suggests to another (the subject) that certain perceptions, feelings, thoughts, or behaviors will spontaneously occur. (p. 265)

hypothalamus [hi-po-THAL-uh-muss] a neural structure lying below (hypo) the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward. (p. 71)

hypothesis a testable prediction, often implied by a theory. (p. 26)

iconic memory a momentary sensory memory of visual stimuli; a photographic or picture-image memory lasting no more than a few tenths of a second. (p. 323)

id a reservoir of unconscious psychic energy that, according to Freud, strives to satisfy basic sexual and aggressive drives. The id operates on the pleasure principle, demanding immediate gratification. (p. 573)

identical twins (monozygotic twins) develop from a single fertilized egg that splits in two, creating two genetically identical organisms. (p. 134)

identification the process by which, according to Freud, children incorporate their parents’ values into their developing superegos. (p. 575)

identity our sense of self; according to Erikson, the adolescent’s task is to solidify a sense of self by testing and integrating various roles. (p. 209)

implicit memory retention of learned skills or classically conditioned associations independent of conscious recollection. (Also called nondeclarative memory.) (pp. 321, 330)

imprinting the process by which certain animals form strong attachments during early life. (p. 196)

inattentional blindness failing to see visible objects when our attention is directed elsewhere. (p. 97)

incentive a positive or negative environmental stimulus that motivates behavior. (p. 421)

independent variable in an experiment, the factor that is manipulated; the variable whose effect is being studied. (p. 37)

individualism giving priority to one’s own goals over group goals and defining one’s identity in terms of personal attributes rather than group identifications. (p. 157)

industrial-organizational (I/O) psychology the application of psychological concepts and methods to optimizing human behavior in workplaces. (p. A-2)

informational social influence influence resulting from one’s willingness to accept others’ opinions about reality. (p. 527)

informed consent giving potential participants enough information about a study to enable them to choose whether they wish to participate. (p. 41)

ingroup “us”—people with whom we share a common identity. (pp. 543, 565)

ingroup bias the tendency to favor our own group. (p. 542)

inner ear the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs. (p. 257)

insight a sudden realization of a problem’s solution; contrasts with strategy-based solutions. (p. 357)

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insight therapies a variety of therapies that aim to improve psychological functioning by increasing a person’s awareness of underlying motives and defenses. (p. 661)

insomnia recurring problems in falling or staying asleep. (p. 110)

instinct a complex behavior that is rigidly patterned throughout a species and is unlearned. (p. 420)

intellectual disability a condition of limited mental ability, indicated by an intelligence test score of 70 or below and difficulty adapting to the demands of life. (Formerly referred to as mental retardation.) (p. 403)

intelligence the mental potential to learn from experience, solve problems, and use knowledge to adapt to new situations. (p. 386)

intelligence quotient (IQ) defined originally as the ratio of mental age (ma) to chronological age (ca) multiplied by 100 (thus, IQ × ma/ca × 100). On contemporary intelligence tests, the average performance for a given age is assigned a score of 100. (p. 394)

intelligence test a method for assessing an individual’s mental aptitudes and comparing them with those of others, using numerical scores. (p. 392)

intensity the amount of energy in a light wave or sound wave, which influences what we perceive as brightness or loudness. Intensity is determined by the wave’s amplitude (height). (p. 239)

interaction the interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity). (p. 142)

internal locus of control the perception that we control our own fate. (p. 503)

interneurons neurons within the brain and spinal cord; communicate internally and process information between the sensory inputs and motor outputs. (p. 60)

interpretation in psychoanalysis, the analyst’s noting supposed dream meanings, resistances, and other significant behaviors and events in order to promote insight. (p. 659)

intimacy in Erikson’s theory, the ability to form close, loving relationships; a primary developmental task in young adulthood. (p. 210)

intrinsic motivation a desire to perform a behavior effectively for its own sake. (p. 305)

intuition an effortless, immediate, automatic feeling or thought, as contrasted with explicit, conscious reasoning. (pp. 20, 359)

iris a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening. (p. 240)

James-Lange theory the theory that our experience of emotion is our awareness of our physiological responses to emotion-arousing stimuli. (p. 460)

just-world phenomenon the tendency for people to believe the world is just and that people therefore get what they deserve and deserve what they get. (p. 541)

kinesthesia [kin-ehs-THEE-zhuh] the system for sensing the position and movement of individual body parts. (p. 269)

language our spoken, written, or signed words and the ways we combine them to communicate meaning. (p. 370)

latent content according to Freud, the underlying meaning of a dream (as distinct from its manifest content). (p. 113)

latent learning learning that occurs but is not apparent until there is an incentive to demonstrate it. (p. 305)

law of effect Thorndike’s principle that behaviors followed by favorable consequences become more likely, and that behaviors followed by unfavorable consequences become less likely. (p. 290)

learned helplessness the hopelessness and passive resignation an animal or human learns when unable to avoid repeated aversive events. (p. 501)

learning the process of acquiring through experience new information or behaviors. (pp. 280, 290, 300)

lens the transparent structure behind the pupil that changes shape to help focus images on the retina. (p. 240)

lesion [LEE-zhuhn] tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue. (p. 66)

levels of analysis the differing complementary views, from biological to psychological to social-cultural, for analyzing any given phenomenon. (p. 9)

limbic system neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives. (p. 71)

linguistic determinism Whorf’s hypothesis that language determines the way we think. (p. 379)

lobotomy a psychosurgical procedure once used to calm uncontrollably emotional or violent patients. The procedure cut the nerves connecting the frontal lobes to the emotion-controlling centers of the inner brain. (p. 687)

longitudinal study research in which the same people are restudied and retested over a long period. (p. 218)

long-term memory the relatively permanent and limitless storehouse of the memory system. Includes knowledge, skills, and experiences. (p. 320)

long-term potentiation (LTP) an increase in a cell’s firing potential after brief, rapid stimulation. Believed to be a neural basis for learning and memory. (p. 332)

LSD a powerful hallucinogenic drug; also known as acid (lysergic acid diethylamide). (p. 124)

major depressive disorder a disorder in which a person experiences, in the absence of drugs or another medical condition, two or more weeks with five or more symptoms, at least one of which must be either (1) depressed mood or (2) loss of interest or pleasure. (p. 629)

mania a hyperactive, wildly optimistic state in which dangerously poor judgment is common. (p. 629)

manifest content according to Freud, the remembered story line of a dream (as distinct from its latent, or hidden, content). (p. 113)

maturation biological growth processes that enable orderly changes in behavior, relatively uninfluenced by experience. (p. 184)

mean the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores. (p. 43)

median the middle score in a distribution; half the scores are above it and half are below it. (p. 43)

medical model the concept that diseases, in this case psychological disorders, have physical causes that can be diagnosed, treated, and, in most cases, cured, often through treatment in a hospital. (p. 612)

medulla [muh-DUL-uh] the base of the brainstem; controls heartbeat and breathing. (p. 69)

memory the persistence of learning over time through the encoding, storage, and retrieval of information. (p. 318)

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memory consolidation the neural storage of a long-term memory. (p. 330)

menarche [meh-NAR-key] the first menstrual period. (p. 166)

menopause the time of natural cessation of menstruation; also refers to the biological changes a woman experiences as her ability to reproduce declines. (p. 214)

mental age a measure of intelligence test performance devised by Binet; the chronological age that most typically corresponds to a given level of performance. Thus, a child who does as well as an average 8-year-old is said to have a mental age of 8. (p. 393)

mental set a tendency to approach a problem in one particular way, often a way that has been successful in the past. (p. 358)

mere exposure effect the phenomenon that repeated exposure to novel stimuli increases liking of them. (p. 551)

meta-analysis a procedure for statistically combining the results of many different research studies. (p. 675)

methamphetamine a powerfully addictive drug that stimulates the central nervous system, with speeded-up body functions and associated energy and mood changes; over time, appears to reduce baseline dopamine levels. (p. 123)

middle ear the chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window. (p. 257)

Minnesota Multiphasic Personality Inventory (MMPI) the most widely researched and clinically used of all personality tests. Originally developed to identify emotional disorders (still considered its most appropriate use), this test is now used for many other screening purposes. (p. 589)

mirror-image perceptions mutual views often held by conflicting people, as when each side sees itself as ethical and peaceful and views the other side as evil and aggressive. (p. 563)

mirror neurons frontal lobe neurons that some scientists believe fire when performing certain actions or when observing another doing so. The brain’s mirroring of another’s action may enable imitation and empathy. (p. 307)

misinformation effect when misleading information has corrupted one’s memory of an event. (p. 344)

mnemonics [nih-MON-iks] memory aids, especially those techniques that use vivid imagery and organizational devices. (p. 325)

mode the most frequently occurring score(s) in a distribution. (p. 43)

modeling the process of observing and imitating a specific behavior. (p. 306)

molecular behavior genetics the study of how the structure and function of genes interact with our environment to influence behavior. (p. 142)

molecular genetics the subfield of biology that studies the molecular structure and function of genes. (p. 142)

monocular cues depth cues, such as interposition and linear perspective, available to either eye alone. (p. 250)

mood-congruent memory the tendency to recall experiences that are consistent with one’s current good or bad mood. (p. 336)

morpheme in a language, the smallest unit that carries meaning; may be a word or a part of a word (such as a prefix). (p. 370)

motivation a need or desire that energizes and directs behavior. (p. 420)

motor cortex an area at the rear of the frontal lobes that controls voluntary movements. (p. 75)

motor (efferent) neurons neurons that carry outgoing information from the brain and spinal cord to the muscles and glands. (p. 60)

MRI (magnetic resonance imaging) a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. MRI scans show brain anatomy. (p. 67)

mutation a random error in gene replication that leads to a change. (p. 145)

myelin [MY-uh-lin] sheath a fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speed as neural impulses hop from one node to the next. (p. 53)

narcissism excessive self-love and self-absorption. (pp. 453, 604)

narcolepsy a sleep disorder characterized by uncontrollable sleep attacks. The sufferer may lapse directly into REM sleep, often at inopportune times. (p. 110)

naturalistic observation a descriptive technique of observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation. (p. 28)

natural selection the principle that, among the range of inherited trait variations, those contributing to reproduction and survival will most likely be passed on to succeeding generations. (pp. 6, 144)

nature–nurture issue the longstanding controversy over the relative contributions that genes and experience make to the development of psychological traits and behaviors. Today’s science sees traits and behaviors arising from the interaction of nature and nurture. (p. 6)

near-death experience an altered state of consciousness reported after a close brush with death (such as through cardiac arrest); often similar to drug-induced hallucinations. (p. 124)

negative reinforcement increasing behaviors by stopping or reducing negative stimuli. A negative reinforcer is any stimulus that, when removed after a response, strengthens the response. (Note: Negative reinforcement is not punishment.) (p. 292)

nerves bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sense organs. (p. 60)

nervous system the body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems. (p. 60)

neurocognitive disorders (NCDs) acquired (not lifelong) disorders marked by cognitive deficits; often related to Alzheimer’s disease, brain injury or disease, or substance abuse. In older adults neurocognitive disorders were formerly called dementia. (p. 218)

neurogenesis the formation of new neurons. (p. 82)

neuron a nerve cell; the basic building block of the nervous system. (p. 53)

neurotransmitters chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse. (p. 56)

neutral stimulus (NS) in classical conditioning, a stimulus that elicits no response before conditioning. (p. 283)

nicotine a stimulating and highly addictive psychoactive drug in tobacco. (p. 121)

G-10

night terrors a sleep disorder characterized by high arousal and an appearance of being terrified; unlike nightmares, night terrors occur during NREM-3 sleep, within two or three hours of falling asleep, and are seldom remembered. (p. 111)

nociceptors sensory receptors that enable the perception of pain in response to potentially harmful stimuli. (p. 262)

norm an understood rule for accepted and expected behavior. Norms prescribe “proper” behavior. (p. 156)

normal curve (normal distribution) a symmetrical, bell-shaped curve that describes the distribution of many types of data; most scores fall near the mean (about 68 percent fall within one standard deviation of it) and fewer and fewer near the extremes. (pp. 45, 396)

normative social influence influence resulting from a person’s desire to gain approval or avoid disapproval. (p. 527)

object permanence the awareness that things continue to exist even when not perceived. (p. 188)

observational learning learning by observing others. (p. 306)

obsessive-compulsive disorder (OCD) a disorder characterized by unwanted repetitive thoughts (obsessions), actions (compulsions), or both. (p. 622)

occipital [ahk-SIP-uh-tuhl] lobes portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual fields. (p. 75)

Oedipus [ED-uh-puss] complex according to Freud, a boy’s sexual desires toward his mother and feelings of jealousy and hatred for the rival father. (p. 574)

one-word stage the stage in speech development, from about age 1 to 2, during which a child speaks mostly in single words. (p. 372)

operant behavior behavior that operates on the environment, producing consequences. (pp. 281, 290)

operant chamber in operant conditioning research, a chamber (also known as a Skinner box) containing a bar or key that an animal can manipulate to obtain a food or water reinforcer; attached devices record the animal’s rate of bar pressing or key pecking. (p. 290)

operant conditioning a type of learning in which behavior is strengthened if followed by a reinforcer or diminished if followed by a punisher. (p. 290)

operational definition a carefully worded statement of the exact procedures (operations) used in a research study. For example, human intelligence may be operationally defined as what an intelligence test measures. (p. 26)

opiates opium and its derivatives, such as morphine and heroin; depress neural activity, temporarily lessening pain and anxiety. (p. 120)

opponent-process theory the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green. (p. 244)

optic nerve the nerve that carries neural impulses from the eye to the brain. (p. 241)

organizational psychology an I/O psychology subfield that examines organizational influences on worker satisfaction and productivity and facilitates organizational change. (p. A-2)

ostracism deliberate social exclusion of individuals or groups. (p. 450)

other-race effect the tendency to recall faces of one’s own race more accurately than faces of other races. Also called the cross-race effect and the own-race bias. (p. 544)

outgroup “them”—those perceived as different or apart from our ingroup. (pp. 543, 564)

overconfidence the tendency to be more confident than correct—to overestimate the accuracy of our beliefs and judgments. (p. 361)

panic disorder an anxiety disorder marked by unpredictable, minutes-long episodes of intense dread in which a person experiences terror and accompanying chest pain, choking, or other frightening sensations. Often followed by worry over a possible next attack. (p. 620)

parallel processing the processing of many aspects of a problem simultaneously; the brain’s natural mode of information processing for many functions. (pp. 96, 246, 320)

paraphilias sexual arousal from fantasies, behaviors, or urges involving nonhuman objects, the suffering of self or others, and/or non-consenting persons. (p. 436)

parapsychology the study of paranormal phenomena, including ESP and psychokinesis. (p. 272)

parasympathetic nervous system the division of the autonomic nervous system that calms the body, conserving its energy. (p. 61)

parietal [puh-RYE-uh-tuhl] lobes portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position. (p. 75)

partial (intermittent) reinforcement schedule reinforcing a response only part of the time; results in slower acquisition of a response but much greater resistance to extinction than does continuous reinforcement. (p. 293)

passionate love an aroused state of intense positive absorption in another, usually present at the beginning of a love relationship. (p. 556)

perception the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events. (p. 230)

perceptual adaptation in vision, the ability to adjust to an artificially displaced or even inverted visual field. (p. 254)

perceptual constancy perceiving objects as unchanging (having consistent color, brightness, shape, and size) even as illumination and retinal images change. (p. 251)

perceptual set a mental predisposition to perceive one thing and not another. (p. 235)

peripheral nervous system (PNS) the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body. (p. 60)

peripheral route persuasion occurs when people are influenced by incidental cues, such as a speaker’s attractiveness. (p. 520)

personality an individual’s characteristic pattern of thinking, feeling, and acting. (p. 572)

personality disorders inflexible and enduring behavior patterns that impair social functioning. (p. 649)

personality inventory a questionnaire (often with true-false or agree-disagree items) on which people respond to items designed to gauge a wide range of feelings and behaviors; used to assess selected personality traits. (p. 589)

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personnel psychology an I/O psychology subfield that focuses on employee recruitment, selection, placement, training, appraisal, and development. (p. A-2)

PET (positron emission tomography) scan a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task. (p. 67)

phi phenomenon an illusion of movement created when two or more adjacent lights blink on and off in quick succession. (p. 251)

phobia an anxiety disorder marked by a persistent, irrational fear and avoidance of a specific object, activity, or situation. (p. 621)

phoneme in a language, the smallest distinctive sound unit. (p. 370)

pitch a tone’s experienced highness or lowness; depends on frequency. (p. 256)

pituitary gland the endocrine system’s most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands. (p. 64)

placebo [pluh-SEE-bo; Latin for “I shall please”] effect experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition, which the recipient assumes is an active agent. (p. 36)

place theory in hearing, the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated. (p. 259)

plasticity the brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience. (p. 81)

polygraph a machine, commonly used in attempts to detect lies, that measures several of the physiological responses (such as perspiration and cardiovascular and breathing changes) accompanying emotion. (p. 467)

population all those in a group being studied, from which samples may be drawn. (Note: Except for national studies, this does not refer to a country’s whole population.) (p. 32)

positive psychology the scientific study of human flourishing, with the goals of discovering and promoting strengths and virtues that help individuals and communities to thrive. (pp. 9, 479)

positive reinforcement increasing behaviors by presenting positive reinforcers. A positive reinforcer is any stimulus that, when presented after a response, strengthens the response. (p. 292)

posthypnotic suggestion a suggestion, made during a hypnosis session, to be carried out after the subject is no longer hypnotized; used by some clinicians to help control undesired symptoms and behaviors. (p. 265)

posttraumatic growth positive psychological changes as a result of struggling with extremely challenging circumstances and life crises. (p. 691)

posttraumatic stress disorder (PTSD) a disorder characterized by haunting memories, nightmares, social withdrawal, jumpy anxiety, numbness of feeling, and/or insomnia that lingers for four weeks or more after a traumatic experience. (p. 623)

predictive validity the success with which a test predicts the behavior it is designed to predict; it is assessed by computing the correlation between test scores and the criterion behavior. (Also called criterion-related validity.) (p. 397)

prejudice an unjustifiable (and usually negative) attitude toward a group and its members. Prejudice generally involves stereotyped beliefs, negative feelings, and a predisposition to discriminatory action. (p. 537)

preoperational stage in Piaget’s theory, the stage (from about 2 to about 6 or 7 years of age) during which a child learns to use language but does not yet comprehend the mental operations of concrete logic. (p. 189)

primary reinforcer an innately reinforcing stimulus, such as one that satisfies a biological need. (p. 292)

primary sex characteristics the body structures (ovaries, testes, and external genitalia) that make sexual reproduction possible. (p. 165)

priming the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response. (pp. 231, 334)

proactive interference the forward-acting disruptive effect of prior learning on the recall of new information. (p. 341)

problem-focused coping attempting to alleviate stress directly—by changing the stressor or the way we interact with that stressor. (p. 500)

projective test a personality test, such as the Rorschach, that provides ambiguous stimuli designed to trigger projection of one’s inner dynamics. (p. 578)

prosocial behavior positive, constructive, helpful behavior. The opposite of antisocial behavior. (p. 310)

prototype a mental image or best example of a category. Matching new items to a prototype provides a quick and easy method for sorting items into categories (as when comparing feathered creatures to a prototypical bird, such as a robin). (p. 356)

psychiatry a branch of medicine dealing with psychological disorders; practiced by physicians who sometimes provide medical (for example, drug) treatments as well as psychological therapy. (p. 12)

psychoactive drug a chemical substance that alters perceptions and moods. (p. 117)

psychoanalysis Sigmund Freud’s theory of personality that attributes thoughts and actions to unconscious motives and conflicts. (2) Freud’s therapeutic technique used in treating psychological disorders. Freud believed that the patient’s free associations, resistances, dreams, and transferences—and the therapist’s interpretations of them—released previously repressed feelings, allowing the patient to gain self-insight. (pp. 572, 658)

psychodynamic theories view personality with a focus on the unconscious and the importance of childhood experiences. (p. 572)

psychodynamic therapy therapy deriving from the psychoanalytic tradition; views individuals as responding to unconscious forces and childhood experiences, and seeks to enhance self-insight. (p. 660)

psychological disorder a syndrome marked by a clinically significant disturbance in an individual’s cognition, emotion regulation, or behavior. (p. 610)

psychology the science of behavior and mental processes. (p. 5)

psychoneuroimmunology the study of how psychological, neural, and endocrine processes together affect the immune system and resulting health. (p. 492)

psychopharmacology the study of the effects of drugs on mind and behavior. (p. 682)

psychophysics the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them. (p. 230)

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psychosexual stages the childhood stages of development (oral, anal, phallic, latency, genital) during which, according to Freud, the id’s pleasure-seeking energies focus on distinct erogenous zones. (p. 574)

psychosurgery surgery that removes or destroys brain tissue in an effort to change behavior. (p. 687)

psychotherapy treatment involving psychological techniques; consists of interactions between a trained therapist and someone seeking to overcome psychological difficulties or achieve personal growth. (pp. 658, 673)

puberty the period of sexual maturation, during which a person becomes capable of reproducing. (pp. 165, 204)

punishment an event that tends to decrease the behavior that it follows. (p. 295)

pupil the adjustable opening in the center of the eye through which light enters. (p. 240)

random assignment assigning participants to experimental and control groups by chance, thus minimizing preexisting differences between the different groups. (p. 35)

random sample a sample that fairly represents a population because each member has an equal chance of inclusion. (p. 30)

range the difference between the highest and lowest scores in a distribution. (p. 45)

recall a measure of memory in which the person must retrieve information learned earlier, as on a fill-in-the-blank test. (p. 319)

reciprocal determinism the interacting influences of behavior, internal cognition, and environment. (p. 595)

reciprocity norm an expectation that people will help, not hurt, those who have helped them. (p. 561)

recognition a measure of memory in which the person need only identify items previously learned, as on a multiple-choice test. (p. 319)

reconsolidation a process in which previously stored memories, when retrieved, are potentially altered before being stored again. (p. 343)

reflex a simple, automatic response to a sensory stimulus, such as the knee-jerk response. (p. 63)

refractory period (1) a period of inactivity after a neuron has fired. (2) a resting period after orgasm, during which a man cannot achieve another orgasm. (pp. 55, 435)

regression toward the mean the tendency for extreme or unusual scores or events to fall back (regress) toward the average. (p. 33)

reinforcement in operant conditioning, any event that strengthens the behavior it follows. (p. 291)

reinforcement schedule a pattern that defines how often a desired response will be reinforced. (p. 293)

relational aggression an act of aggression (physical or verbal) intended to harm a person’s relationship or social standing. (p. 162)

relative deprivation the perception that one is worse off relative to those with whom one compares oneself. (p. 484)

relearning a measure of memory that assesses the amount of time saved when learning material again. (p. 319)

reliability the extent to which a test yields consistent results, as assessed by the consistency of scores on two halves of the test, on alternative forms of the test, or on retesting. (p. 397)

REM rebound the tendency for REM sleep to increase following REM sleep deprivation (created by repeated awakenings during REM sleep). (p. 116)

REM sleep rapid eye movement sleep; a recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active. (p. 101)

repetitive transcranial magnetic stimulation (rTMS) the application of repeated pulses of magnetic energy to the brain; used to stimulate or suppress brain activity. (p. 686)

replication repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding extends to other participants and circumstances. (p. 26)

repression in psychoanalytic theory, the basic defense mechanism that banishes from consciousness anxiety-arousing thoughts, feelings, and memories. (pp. 343, 575)

resilience the personal strength that helps most people cope with stress and recover from adversity and even trauma. (p. 690)

resistance in psychoanalysis, the blocking from consciousness of anxiety-laden material. (p. 659)

respondent behavior behavior that occurs as an automatic response to some stimulus. (pp. 281, 290)

reticular formation a nerve network that travels through the brainstem into the thalamus and plays an important role in controlling arousal. (p. 70)

retina the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information. (p. 240)

retinal disparity a binocular cue for perceiving depth: By comparing images from the retinas in the two eyes, the brain computes distance—the greater the disparity (difference) between the two images, the closer the object. (p. 249)

retrieval the process of getting information out of memory storage. (pp. 320, 329)

retroactive interference the backward-acting disruptive effect of new learning on the recall of old information. (p. 341)

retrograde amnesia an inability to retrieve information from one’s past. (p. 338)

reuptake a neurotransmitter’s reabsorption by the sending neuron. (p. 56)

rods retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don’t respond. (p. 241)

role a set of expectations (norms) about a social position, defining how those in the position ought to behave. (pp. 167, 523)

Rorschach inkblot test the most widely used projective test, a set of 10 inkblots, designed by Hermann Rorschach; seeks to identify people’s inner feelings by analyzing their interpretations of the blots. (p. 578)

rumination compulsive fretting; overthinking about our problems and their causes. (p. 635)

savant syndrome a condition in which a person otherwise limited in mental ability has an exceptional specific skill, such as in computation or drawing. (p. 387)

G-13

scapegoat theory the theory that prejudice offers an outlet for anger by providing someone to blame. (p. 542)

scatterplot a graphed cluster of dots, each of which represents the values of two variables. The slope of the points suggests the direction of the relationship between the two variables. The amount of scatter suggests the strength of the correlation (little scatter indicates high correlation). (p. 32)

schema a concept or framework that organizes and interprets information. (p. 187)

schizophrenia a psychological disorder characterized by delusions, hallucinations, disorganized speech, and/or diminished, inappropriate emotional expression. (p. 640)

secondary sex characteristics nonreproductive sexual traits, such as female breasts and hips, male voice quality, and body hair. (p. 165)

selective attention the focusing of conscious awareness on a particular stimulus. (p. 96)

self in contemporary psychology, assumed to be the center of personality, the organizer of our thoughts, feelings, and actions. (p. 598)

self-actualization according to Maslow, one of the ultimate psychological needs that arises after basic physical and psychological needs are met and self-esteem is achieved; the motivation to fulfill one’s potential. (p. 583)

self-concept all our thoughts and feelings about ourselves, in answer to the question, “Who am I?” (pp. 200, 584)

self-control the ability to control impulses and delay short-term gratification for greater long-term rewards. (p. 503)

self-disclosure the act of revealing intimate aspects of oneself to others. (p. 557)

self-efficacy one’s sense of competence and effectiveness. (p. 599)

self-esteem one’s feelings of high or low self-worth. (p. 599)

self-fulfilling prophecy a belief that leads to its own fulfillment. (p. 563)

self-serving bias a readiness to perceive oneself favorably. (p. 601)

sensation the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment. (p. 230)

sensorimotor stage in Piaget’s theory, the stage (from birth to nearly 2 years of age) during which infants know the world mostly in terms of their sensory impressions and motor activities. (p. 188)

sensorineural hearing loss the most common form of hearing loss, also called nerve deafness; caused by damage to the cochlea’s receptor cells or to the auditory nerves. (p. 257)

sensory adaptation diminished sensitivity as a consequence of constant stimulation. (p. 234)

sensory (afferent) neurons neurons that carry incoming information from the sensory receptors to the brain and spinal cord. (p. 60)

sensory interaction the principle that one sense may influence another, as when the smell of food influences its taste. (p. 270)

sensory memory the immediate, very brief recording of sensory information in the memory system. (p. 320)

serial position effect our tendency to recall best the last (a recency effect) and first (a primacy effect) items in a list. (p. 336)

set point the point at which your “weight thermostat” is supposedly set. When your body falls below this weight, increased hunger and a lowered metabolic rate may combine to restore the lost weight. (p. 427)

sex in psychology, the biologically influenced characteristics by which people define males and females. (p. 161)

sexual dysfunction a problem that consistently impairs sexual arousal or functioning. (p. 435)

sexual orientation an enduring sexual attraction toward members of one’s own sex (homosexual orientation), the other sex (heterosexual orientation), or both sexes (bisexual orientation). (p. 440)

sexual response cycle the four stages of sexual responding described by Masters and Johnson—excitement, plateau, orgasm, and resolution. (p. 435)

shallow processing encoding on a basic level based on the structure or appearance of words. (p. 326)

shaping an operant conditioning procedure in which reinforcers guide behavior toward closer and closer approximations of the desired behavior. (p. 291)

short-term memory activated memory that holds a few items briefly, such as the seven digits of a phone number while calling, before the information is stored or forgotten. (p. 320)

signal detection theory a theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single absolute threshold and that detection depends partly on a person’s experience, expectations, motivation, and alertness. (p. 231)

sleep periodic, natural loss of consciousness—as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation. (Adapted from Dement, 1999.) (p. 100)

sleep apnea a sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings. (p. 111)

social clock the culturally preferred timing of social events such as marriage, parenthood, and retirement. (p. 220)

social-cognitive perspective views behavior as influenced by the interaction between people’s traits (including their thinking) and their social context. (p. 594)

social exchange theory the theory that our social behavior is an exchange process, the aim of which is to maximize benefits and minimize costs. (p. 561)

social facilitation improved performance on simple or well-learned tasks in the presence of others. (p. 532)

social identity the “we” aspect of our self-concept; the part of our answer to “Who am I?” that comes from our group memberships. (p. 209)

social leadership group-oriented leadership that builds teamwork, mediates conflict, and offers support. (p. A-12)

social learning theory the theory that we learn social behavior by observing and imitating and by being rewarded or punished. (p. 168)

social loafing the tendency for people in a group to exert less effort when pooling their efforts toward attaining a common goal than when individually accountable. (p. 533)

social psychology the scientific study of how we think about, influence, and relate to one another. (p. 418)

social-responsibility norm an expectation that people will help those needing their help. (p. 560)

social script culturally modeled guide for how to act in various situations. (pp. 150, 548)

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social trap a situation in which the conflicting parties, by each pursuing their self-interest rather than the good of the group, become caught in mutually destructive behavior. (p. 562)

somatic nervous system the division of the peripheral nervous system that controls the body’s skeletal muscles. Also called the skeletal nervous system. (p. 60)

somatosensory cortex area at the front of the parietal lobes that registers and processes body touch and movement sensations. (p. 78)

source amnesia attributing to the wrong source an event we have experienced, heard about, read about, or imagined. (Also called source misattribution.) Source amnesia, along with the misinformation effect, is at the heart of many false memories. (p. 346)

spacing effect the tendency for distributed study or practice to yield better long-term retention than is achieved through massed study or practice. (p. 325)

spermarche [sper-MAR-key] first ejaculation. (p. 166)

split brain a condition resulting from surgery that isolates the brain’s two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them. (p. 83)

spontaneous recovery the reappearance, after a pause, of an extinguished conditioned response. (p. 285)

spotlight effect overestimating others’ noticing and evaluating our appearance, performance, and blunders (as if we presume a spotlight shines on us). (p. 598)

SQ3R a study method incorporating five steps: Survey, Question, Read, Retrieve, Review. (p. 14)

standard deviation a computed measure of how much scores vary around the mean score. (p. 45)

standardization defining uniform testing procedures and meaningful scores by comparison with the performance of a pretested group. (p. 396)

Stanford-Binet the widely used American revision (by Terman at Stanford University) of Binet’s original intelligence test. (p. 394)

statistical significance a statistical statement of how likely it is that an obtained result occurred by chance. (p. 47)

stereotype a generalized (sometimes accurate but often overgeneralized) belief about a group of people. (p. 538)

stereotype threat a self-confirming concern that one will be evaluated based on a negative stereotype. (p. 414)

stimulants drugs (such as caffeine, nicotine, and the more powerful amphetamines, cocaine, Ecstasy, and methamphetamine) that excite neural activity and speed up body functions. (p. 120)

stimulus any event or situation that evokes a response. (pp. 281, 290)

storage the process of retaining encoded information over time. (pp. 320, 329)

stranger anxiety the fear of strangers that infants commonly display, beginning by about 8 months of age. (p. 195)

stress the process by which we perceive and respond to certain events, called stressors, that we appraise as threatening or challenging. (p. 488)

structuralism early school of thought promoted by Wundt and Titchener; used introspection to reveal the structure of the human mind. (p. 3)

structured interviews interview process that asks the same job-relevant questions of all applicants, each of whom is rated on established scales. (p. A-6)

subjective well-being self-perceived happiness or satisfaction with life. Used along with measures of objective well-being (for example, physical and economic indicators) to evaluate people’s quality of life. (p. 479)

subliminal below one’s absolute threshold for conscious awareness. (p. 231)

substance use disorder continued substance craving and use despite significant life disruption and/or physical risk. (p. 117)

superego the part of personality that, according to Freud, represents internalized ideals and provides standards for judgment (the conscience) and for future aspirations. (p. 574)

superordinate goals shared goals that override differences among people and require their cooperation. (p. 565)

suprachiasmatic nucleus (SCN) a pair of cell clusters in the hypothalamus that controls circadian rhythm. In response to light, the SCN causes the pineal gland to adjust melatonin production, thus modifying our feelings of sleepiness. (p. 104)

survey a descriptive technique for obtaining the self-reported attitudes or behaviors of a particular group, usually by questioning a representative, random sample of the group. (p. 30)

sympathetic nervous system the division of the autonomic nervous system that arouses the body, mobilizing its energy. (p. 61)

synapse [SIN-aps] the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft. (p. 56)

systematic desensitization a type of exposure therapy that associates a pleasant relaxed state with gradually increasing anxiety-triggering stimuli. Commonly used to treat phobias. (p. 664)

task leadership goal-oriented leadership that sets standards, organizes work, and focuses attention on goals. (p. A-11)

telegraphic speech early speech stage in which a child speaks like a telegram—“go car”—using mostly nouns and verbs. (p. 372)

temperament a person’s characteristic emotional reactivity and intensity. (p. 140)

temporal lobes portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving information primarily from the opposite ear. (p. 75)

tend and befriend under stress, people (especially women) often provide support to others (tend) and bond with and seek support from others (befriend). (p. 492)

teratogens (literally, “monster maker”) agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause harm. (p. 182)

terror-management theory a theory of death-related anxiety; explores people’s emotional and behavioral responses to reminders of their impending death. (p. 581)

testing effect enhanced memory after retrieving, rather than simply rereading, information. Also sometimes referred to as a retrieval practice effect or test-enhanced learning. (pp. 13, 326)

testosterone the most important of the male sex hormones. Both males and females have it, but the additional testosterone in males stimulates the growth of the male sex organs during the fetal period, and the development of the male sex characteristics during puberty. (pp. 165, 433)

thalamus [THAL-uh-muss] the brain’s sensory control center, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla. (p. 70)

G-15

THC the major active ingredient in marijuana; triggers a variety of effects, including mild hallucinations. (p. 125)

Thematic Apperception Test (TAT) a projective test in which people express their inner feelings and interests through the stories they make up about ambiguous scenes. (p. 578)

theory an explanation using an integrated set of principles that organizes observations and predicts behaviors or events. (p. 26)

theory of mind people’s ideas about their own and others’ mental states—about their feelings, perceptions, and thoughts, and the behaviors these might predict. (p. 190)

therapeutic alliance a bond of trust and mutual understanding between a therapist and client, who work together constructively to overcome the client’s problem. (p. 679)

threshold the level of stimulation required to trigger a neural impulse. (p. 55)

token economy an operant conditioning procedure in which people earn a token of some sort for exhibiting a desired behavior and can later exchange their tokens for various privileges or treats. (p. 666)

tolerance the diminishing effect with regular use of the same dose of a drug, requiring the user to take larger and larger doses before experiencing the drug’s effect. (p. 118)

top-down processing information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations. (p. 230)

trait a characteristic pattern of behavior or a disposition to feel and act, as assessed by self-report inventories and peer reports. (p. 586)

transduction conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brain can interpret. (p. 230)

transference in psychoanalysis, the patient’s transfer to the analyst of emotions linked with other relationships (such as love or hatred for a parent). (p. 659)

transgender an umbrella term describing people whose gender identity or expression differs from that associated with their birth sex. (p. 169)

two-factor theory the Schachter-Singer theory that to experience emotion one must (1) be physically aroused and (2) cognitively label the arousal. (p. 461)

two-word stage beginning about age 2, the stage in speech development during which a child speaks mostly in two-word statements. (p. 372)

Type A Friedman and Rosenman’s term for competitive, hard-driving, impatient, verbally aggressive, and anger-prone people. (p. 497)

Type B Friedman and Rosenman’s term for easygoing, relaxed people. (p. 497)

unconditional positive regard a caring, accepting, nonjudgmental attitude, which Carl Rogers believed would help clients develop self-awareness and self-acceptance. (pp. 584, 662)

unconditioned response (UR) in classical conditioning, an unlearned, naturally occurring response (such as salivation) to an unconditioned stimulus (US) (such as food in the mouth). (p. 283)

unconditioned stimulus (US) in classical conditioning, a stimulus that unconditionally—naturally and automatically—triggers an unconditioned response (UR). (p. 283)

unconscious according to Freud, a reservoir of mostly unacceptable thoughts, wishes, feelings, and memories. According to contemporary psychologists, information processing of which we are unaware. (p. 573)

validity the extent to which a test measures or predicts what it is supposed to. (See also content validity and predictive validity.) (p. 397)

variable-interval schedule in operant conditioning, a reinforcement schedule that reinforces a response at unpredictable time intervals. (p. 294)

variable-ratio schedule in operant conditioning, a reinforcement schedule that reinforces a response after an unpredictable number of responses. (p. 294)

vestibular sense the sense of body movement and position, including the sense of balance. (p. 269)

virtual reality exposure therapy an anxiety treatment that progressively exposes people to electronic simulations of their greatest fears, such as airplane flying, spiders, or public speaking. (p. 664)

visual cliff a laboratory device for testing depth perception in infants and young animals. (p. 249)

wavelength the distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission. (p. 239)

Weber’s law the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount). (p. 233)

Wechsler Adult Intelligence Scale (WAIS) the WAIS and its companion versions for children are the most widely used intelligence tests; contain verbal and performance (nonverbal) subtests. (p. 395)

Wernicke’s area controls language reception—a brain area involved in language comprehension and expression; usually in the left temporal lobe. (p. 376)

withdrawal the discomfort and distress that follow discontinuing an addictive drug or behavior. (p. 118)

working memory a newer understanding of short-term memory that focuses on conscious, active processing of incoming auditory and visual-spatial information, and of information retrieved from long-term memory. (p. 321)

X chromosome the sex chromosome found in both men and women. Females have two X chromosomes; males have one. An X chromosome from each parent produces a female child. (p. 165)

Y chromosome the sex chromosome found only in males. When paired with an X chromosome from the mother, it produces a male child. (p. 165)

Yerkes-Dodson law the principle that performance increases with arousal only up to a point, beyond which performance decreases. (p. 422)

Young-Helmholtz trichromatic (three-color) theory the theory that the retina contains three different color receptors—one most sensitive to red, one to green, one to blue—which, when stimulated in combination, can produce the perception of any color. (p. 243)

zygote the fertilized egg; it enters a 2-week period of rapid cell division and develops into an embryo. (p. 181)