Psychology Space

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November 10, 2005

Phychology Terminology

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Absolute Threshold – The minimum value of a stimulus that can be detected.

Accommodation – Changes in the thickness of the lens of the eye that focus images of near or distant objects on the retina. Also, the process by which existing schemata are modified or changed by new experiences.

Acquisition – In classical conditioning, the time during which a CR first appears and increases in frequency.

Action Potential – A brief electrochemical event that is carried by an axon from the soma of the neuron to its terminal buttons; causes the release of a transmitter substance.

Activational Effect – The effect of a hormone on a physiological system that has already developed. If the effect involves the brain, it can influence behavior. An example is facilitation of sexual arousal and performance.

Actor-Observer Effect – The tendency to attribute one’s own behavior to situational factors but others’ behavior to dispositional factors.

Adaptive Significance – The effectiveness of behavior in aiding organisms in adjusting to changing environmental conditions.

Aerobic Exercises – Physical activity that expends considerable energy, increases blood flow and respiration and thereby stimulates and strengthens the heart and lungs and increase the body’s efficient use of oxygen.

Agoraphobia – A mental disorder characterized by fear of and avoidance of being alone in public places; this disorder is often accompanied by panic attacks.

Agrammatism – A language disturbance; difficulty in the production and comprehension of grammatical features, such as proper use of function words, word endings, and word order. Often seen in cases of Broca’s aphasia.

Alcoholism – An addiction to ethanol, which is the psychoactive agent in alcohol.

Algorithm – A procedure that consists of a series of steps that will solve a specific type of problem.

Alleles – Alternative forms of the same gene.

Alpha Activity – Rhythmical, medium-frequency activity of the electroencephalogram, usually indicating a state of quiet relaxation.

Altruism – The unselfish concern of one individual for the welfare of another.

Alzheimer’s disease – A fatal degenerative disease in which neurons of the brain progressively die, causing loss of memory and other cognitive processes.

Amygdala – A part of the limbic system of the brain located deep in the temporal lobe; damage causes changes in emotional and aggressive behavior.

Anal Stage – The second of Freud’s psychosexual stages, during which the primary erogenous zone is the anal region. During this time, children take pleasure in retaining or expelling feces.

Anatomical Coding – A means of representing information by the nervous system; different features are coded by the activity of different neurons.

Androgen Insensitivity Syndrome – An inherited condition caused by a lack of functioning androgen receptors. Because androgens cannot exert their effects, a person with XY sex chromosomes develops as a female, with female external genitalia.

Androgens – The primary class of sex hormones in males. The most important androgen is testosterone.

Animism – The belief that all animals and all moving objects possess spirits providing their motive force.

Anorexia Nervosa – An eating disorder characterized by attempts to lose weight, sometimes to the point of starvation.

Anterior/Posterior – Toward the front/back.

Anterograde Amnesia – A disorder caused by brain damage that disrupts a person’s ability to form new long-term memories of events that occur after the time of the brain damage.

Antianxiety Drug – A “tranquilizer,” which reduces anxiety. The most common include chlordiazepoxide (Librium) and diazepam (Valium).

Antianxiety Drugs – Drugs used to treat anxiety-related disorders.

Antibodies – Proteins in the immune system that recognize antigens and help kill invading microorganisms.

Anticipatory Anxiety – A fear of having a panic attack; may lead to the development of agoraphobia.

Antidepressant Drugs – Drugs used to treat depression.

Antigen – The unique proteins found on the surface of bacteria; these proteins are what enable the immune system to recognize the bacteria as foreign substances.

Antimanic Drugs – Drugs used to treat bipolar disorder and mania.

Antipsychotic Drugs – Drugs used to treat psychotic disorders such as schizophrenia.

Antisocial Personality Disorder – A disorder characterized by a failure to conform to standards of decency; repeated lying and stealing; a failure to sustain lasting, loving relationships; low tolerance of boredom; and a complete lack of guilt.

Anxiety – A sense of apprehension or doom that is accompanied by many physiological reactions, such as accelerated heart rate, sweaty palms, and tightness in the stomach.

Appeasement Gesture – A stereotyped gesture made by a submissive animal in response to a threat gesture by a dominant animal; tends to inhibit an attack.

Archetypes – Universal thought forms and patterns that Jung believed resided in the collective unconscious.

Artificial Intelligence – A field of study in which computer programs are designed to simulate human cognitive abilities with the expectation that the endeavor will help the investigator understand the mechanisms that underlie these abilities.

Artificial Selection – A procedure in which animals are deliberately mated to produce offspring that possess particularly desirable characteristics.

Assimilation – The process by which new information about the world is modified to fit existing schemata.

Attachment – A social and emotional bond between infant and caregiver that spans both time and space.

Attitude – An evaluation of persons, places, and things.

Attribution – The process by which people infer the causes of other people’s behavior.

Auditory Hair Cell – The sensory neuron of the auditory system; located on the basilar membrane.

Autoimmune Diseases – Diseases such as rheumatoid arthritis, diabetes, lupus, and multiple sclerosis, in which the immune system attacks and destroys some of the body’s own tissue.

Automatic Processing – The formation of memories of events and experiences with little or no attention or effort.

Autonomic Nervous System (ANS) – The portion of the peripheral nervous system that controls the functions of the glands and internal organs.

Availability Heuristic – A general rule for decision making through which a person judges the likelihood or importance of an event by the ease with which examples of that event come to mind.

Aversion Therapy – A form of treatment in which the client is trained to respond negatively to a neutral stimulus that has been paired with an aversive stimulus.

Avoidance Response – An operant response acquired through negative reinforcement that prevents an aversive stimulus from occurring.

Avoidant Attachment – A kind of attachment in which infants avoid or ignore their mothers and often do not cuddle when held.

Axon – A long, thin part of a neuron attached to the soma; divides into a few or many branches, ending in terminal buttons.

B Lymphocytes – Cells that develop in bone marrow and release immunoglobulins to defend the body against antigens.

Backward Masking – The ability of a stimulus to interfere with the perception of a stimulus presented just before it.

Balint’s Syndrome – A syndrome caused by bilateral damage to the parieto-occipital region of the brain; includes difficulty in perceiving the location of objects and reaching for them under visual guidance.

Barbiturate – A drug that causes sedation; one of several derivatives of barbituric acid.

Base-Rate Fallacy – The failure to consider the likelihood that a person, place, or thing is a member of a particular category.

Basic Orientations – Horney’s sets of personality characteristics that correspond to the strategies of moving toward others, moving against others, and moving away from others.

Basic Rest-Activity Cycle (BRAC) – A 90-minute cycle (in humans) of waxing and waning alertness controlled by a biological clock in the pons; during sleep, it controls cycles of REM sleep and slow-wave sleep.

Basic-Level Concept – A concept that makes important distinctions between different categories.

Basilar Membrane – A membrane that divides the cochlea of the inner ear into two compartments. The receptive organ for audition resides here.

Behavior Analysis – A branch of psychology that studies the effect of the environment on behavior; primarily, the effects of the consequences of behaviors on the behaviors themselves.

Behavior Genetics – The branch of psychology that studies the role of genetics in behavior.

Behavior Modification – Behavior therapy based on the principles of operant conditioning.

Behavioral Pharmacology – The study of how drugs influence behavior; combines the principles of operant conditioning with the principles of drug action.

Behaviorism – A movement in psychology that asserts that the only proper subject matter for scientific study in psychology is observable behavior.

Belief In a Just World – The belief that people get what they deserve in life; a fundamental attribution error.

Benzodiazepine – A class of drugs having anxiolytic (“tranquilizing”) effects; examples are Librium and Valium.

Beta Activity – The irregular, high-frequency activity of the electroencephalogram, usually indicating a state of alertness or arousal.

Binet-Simon Scale – An intelligence test developed by Binet and Simon in 1905; the precursor of the Stanford-Binet Scale.

Biological Evolution – Changes in the genetic or physical characteristics of a population or group of organisms over time.

Bipedalism – The ability to move about the environment on two feet.

Bipolar Cell – A neuron in the retina that receives information from photoreceptors and passes it on to the ganglion cells, from which axons proceed through the optic nerves to the brain.

Bipolar Disorder – Alternating states of depression and mania separated by periods of relatively normal affect.

Bottom-Up Processing – A perception based on successive analyses of the details of the stimuli that are present.

Brain Lesion – Damage to a particular region of the brain.

Brain Stem – The “stem” of the brain, including the medulla, pons, and midbrain.

Brightness – A perceptual dimension of color, most closely related to the intensity or degree of radiant energy emitted by a visual stimulus.

Brightness Constancy – The tendency to perceive objects as having constant brightness even when they are observed under varying levels of illumination.

Broca’s Aphasia – Severe difficulty in articulating words, especially function words, caused by damage that includes Broca’s area, a region of the frontal cortex on the left (speech-dominant) side of the brain.

Bulimia Nervosa – A loss of control over food intake characterized by gorging binges followed by self-induced vomiting or use of laxatives; also accompanied by feelings of guilt and depression.

Bystander Intervention – The intervention of a person in a situation that appears to require his or her aid.

Case Study – Observation of the behavior of individuals having special characteristics, such as psychological or neurological disorders.

Cataplexy – A neurological disorder in which the person collapses, becoming temporarily paralyzed but not unconscious; usually triggered by anger or excitement; apparently related to the paralysis that normally accompanies REM sleep.

Catatonic Schizophrenia – A form of schizophrenia characterized primarily by various motor disturbances, including catatonic postures and waxy flexibility.

Causal Event – An event that causes another event to occur.

Central Nervous System – The brain and the spinal cord.

Central Traits – Personality attributes that seem to be the most typical of a particular individual.

Cerebellum – A pair of hemispheres resembling the cerebral hemispheres but much smaller and lying beneath and in back of them; controls posture and movements, especially rapid ones.

Cerebral Cortex – The outer layer of the cerebral hemispheres of the brain, approximately 3 mm thick.

Cerebral Hemisphere – The largest part of the brain; covered by the cerebral cortex and contains parts of the brain that evolved most recently.

Cerebrospinal Fluid (CSF) – The liquid in which the brain and spinal cord float; provides a shock-absorbing cushion.

Chemosense – One of the two sense modalities (gustation and olfaction) that detect the presence of particular molecules present in the environment.

Child-Directed Speech – The speech of an adult directed toward a child; differs in important features from adult-directed speech and tends to facilitate learning of language by children.

Chromatopsia – The inability to discriminate among different hues; caused by damage to the visual association cortex.

Chromosomal Aberration – The rearrangement of genes within cells or a change in the total number of chromosomes.

Chromosomes – Rodlike structures in the nuclei of living cells that contain genes.

Chunking – A process by which information is simplified by rules that make it easier to remember. For example, the string of letters TWAABCFBI is easier to remember if a person learns the rule that organizes it into smaller “chunks”: TWA, ABC, and FBI.

Cilium – A hairlike appendage of a cell; involved in movement or in transducing sensory information. Cilia are found on the receptors in the auditory and vestibular system.

Cingulotomy – Surgical destruction of the cingulum bundle, which connects the prefrontal cortex with the limbic system; helps to reduce intense anxiety and the symptoms of obsessive-compulsive disorder.

Circadian Rhythm – A daily rhythmical change in behavior or physiological process.

Classical Conditioning – The process by which a response normally elicited by one stimulus (the UCS) comes to be controlled by another stimulus (the CS) as well.

Client-Centered Therapy – A form of therapy in which the client is allowed to decide what to talk about without strong direction and judgment from the therapist.

Clinical Psychology – The branch of psychology devoted to the investigation and treatment of abnormal behavior and mental disorders.

Cochlea – The snail-shaped chamber set in bone in the inner ear, where audition takes place.

Cognitive Appraisal – One’s perception of a stressful situation.

Cognitive Dissonance Theory – The theory that changes in attitudes can be motivated by an unpleasant state of tension caused by a disparity between a person’s beliefs or attitudes and behavior, especially beliefs or attitudes that are related to the person’s self-esteem.

Cognitive Psychology – The branch of psychology that studies complex behaviors and mental processes such as perception, attention, learning and memory, verbal behavior, concept formation, and problem solving.

Cognitive Reappraisal – Any coping strategy in which one alters one’s perception of the threat posed by a stressor to reduce stress.

Cognitive Restructuring – The process of replacing the client’s maladaptive thoughts with more constructive ways of thinking.

Cognitive Structures – According to Piaget, mental representations or rules, such as schemata or concepts, that are used for understanding and dealing with the world and for thinking about and solving problems.

Cognitive-Behavior Therapy – A treatment method that focuses on altering the client’s thoughts, beliefs, and perceptions.

Collective Unconscious – According to Jung, the part of the unconscious that contains memories and ideas inherited from our ancestors over the course of evolution.

Color Mixing – The perception of two or more lights of different wavelengths seen together as light of an intermediate wavelength.

Community Psychology – A form of treatment and education whose goal is to address psychological problems through an assessment of the sociocultural context in which they develop.

Companionate Love – Love that is characterized by a deep, enduring affection and caring for another person, accompanied by a strong desire to maintain the relationship.

Comparative Psychology – A branch of psychology that studies the behaviors of a variety of organisms in an attempt to understand the adaptive and functional significance of the behaviors and their relation to evolution.

Competition – A striving or vying with others who share the same ecological niche for food, mates, and territory.

Compliance – Engaging in a particular behavior at another person’s request.

Componential Intelligence – According to Sternberg, the mental mechanisms people use to plan and execute tasks; includes metacomponents, performance components, and knowledge acquisition components.

Compulsion – An irresistible impulse to repeat some action over and over even though it serves no useful purpose.

Concept – A category of objects or situations that share some common attributes.

Concordance Research – Research that studies the degree of similarity in traits expressed between twins. Twins are said to be concordant for a trait if either both or neither twin expresses it and discordant if only one twin expresses it.

Conditional Response – In classical conditioning, the response elicited by the CS.

Conditional Stimulus – In classical conditioning, a stimulus which, because of its repeated association with the UCS, eventually elicits a CR.

Conditioned (or Secondary) Reinforcer (or Punisher) – A stimulus that acquires its reinforcing (or punishing) properties through association with a primary reinforcer (or punisher). Sometimes referred to as a secondary reinforcer (or punisher).

Conditioned Emotional Response – A classically conditioned response produced by an unconditional stimulus that elicits an emotional response-in most cases, including behavioral and physiological components.

Conditioned Flavor-Aversion Learning – A type of learning in which a substance is avoided because its flavor has been associated with illness.

Conditions of Worth – Conditions that others place on us for receiving their positive regard.

Conduction Aphasia – An inability to remember words that are heard, although they usually can be understood and responded to appropriately. This disability is caused by damage to Wernicke’s and Broca’s areas.

Cone – One of the photoreceptors in the retina; responsible for acute daytime vision and for color perception.

Confidentiality – Privacy of subjects and nondisclosure of their participation in a research project.

Confirmation Bias – A tendency to seek evidence that might confirm a hypothesis rather than evidence that might disconfirm it; a logical error.

Conformity – The adoption of attitudes and behaviors shared by a particular group of people.

Confounding of Variables – An inadvertent alteration of more than one variable during an experiment. The results of an experiment involving confounded variables permit no valid conclusions about cause and effect.

Conjugate Movement – The cooperative movement of the eyes, which ensures that the image of an object falls on identical portions of both retinas.

Conscience – The internalization of the rules and restrictions of society; it determines which behaviors are permissible and punishes wrongdoing with feelings of guilt.

Consensual Behavior – Behavior that is shared by many people; behavior that is similar from one person to the next. To the extent that people engage in the same behavior, their behavior is consensual.

Conservation – Understanding that specific properties of objects (height, weight, volume, length) remain the same despite apparent changes in the shape or arrangement of those objects.

Consistency – The extent to which a person’s behavior is consistent across time.

Consolidation – The process by which information in short-term memory is transfered to long-term memory, presumably because of physical changes that occur in neurons in the brain.

Content Word – A noun, verb, adjective, or adverb that conveys meaning. See also function word.

Contextual Intelligence – According to Sternberg, intelligence that reflects behaviors that were subject to natural selection: adaptation-fitting into the environment by developing useful skills and behaviors; selection-finding a niche in the environment; and shaping-changing the environment.

Contralateral – Residing in the side of the body opposite the reference point.

Control Group – A comparison group used in an experiment, the members of which are exposed to the naturally occurring or zero value of the independent variable.

Conventional Level – Kohlberg’s second level of moral development, in which people realize that society has instituted moral rules to maintain order and to serve the best interests of its citizenry.

Convergence – The result of conjugate eye movements whereby the fixation point for each eye is identical; feedback from these movements provides information about the distance of objects from the viewer.

Conversion – A defense mechanism that involves converting an intrapsychic conflict into a physical form, such as blindness, deafness, paralysis, or numbness.

Conversion Disorder – A somatoform disorder involving the actual loss of bodily function, such as blindness, paralysis, and numbness, due to excessive anxiety.

Coping Response – A response that permits an animal to escape, avoid, or minimize the stressful (harmful or painful) effects of an aversive stimulus.

Coping Strategy – A plan of action that a person follows to reduce the perceived level of stress, either in anticipation of a stressor or in response to its occurrence.

Cornea – The transparent tissue covering the front of the eye.

Corpus Callosum – A large bundle of axons (“white matter”) that connects the cortex of the two cerebral hemispheres.

Correctional Mechanism – In a regulatory process, the mechanism that is capable of restoring the system variable to the set point.

Correlation Coefficient – A measurement of the degree to which two variables are related.

Correlational Study – The observation of two or more variables in the behavior or other characteristics of people or other animals.

Counterbalancing – A systematic variation of conditions in an experiment, such as the order of presentation of stimuli, so that different subjects encounter them in different orders; prevents confounding of independent variables with time-dependent processes such as habituation or fatigue.

Countertransference – The process by which the therapist projects his or her emotions onto the client.

Covert Sensitization – A method used by behavior therapists in which a client imagines the aversive consequences of his or her inappropriate behavior.

Cranial Nerve – A bundle of nerve fibers attached to the base of the brain, conveying sensory information from the face and head and carrying messages to muscles and glands.

Criterion – An independent measure of a variable being assessed. For example, college grades are the criterion measure for scores on the Scholastic Aptitude Test.

Critical Period – A specific time in development during which certain experiences must occur for normal development to occur.

Cross-Cultural Psychology – The branch of psychology that studies the effects of culture on behavior.

CT Scanner – A device that uses a special X-ray machine and a computer to produce images of the brain that appear as slices taken parallel to the top of the skull.

Cultural Evolution – The adaptive change of a culture to recurrent environmental pressures.

Culture – The sum of socially-transmitted knowledge, customs, and behavior patterns common to a particular group of people.

Culture-Bound Syndromes – Highly unusual mental disorders, similar in nature to nonpsychotic mental disorders, that appear to be specific to only one or a few cultures.

Cumulative Recorder – A mechanical device connected to an operant chamber for the purpose of recording operant responses as they occur in time.

Dark Adaptation – The process by which the eye becomes capable of distinguishing dimly illuminated objects after going from a bright region to a dark one.

Debriefing – Full disclosure to research participants of the true nature and purpose of a research project after its completion.

Deductive Reasoning – Inferring specific instances from general principles or rules.

Deep Processing – The analysis of the complex characteristics of a stimulus, such as its meaning or its relationship to other stimuli.

Deep Structure – The essential meaning of a sentence, without regard to the grammatical features (surface structure) of the sentence that are needed to express it in words. See also surface structure.

Defense Mechanisms – Mental systems that become active whenever unconscious instinctual drives of the id come into conflict with internalized prohibitions of the superego.

Deferred Imitation – A child’s ability to imitate the actions he or she has observed others perform. Piaget believed deferred imitation to result from the child’s increasing ability to form mental representations of behavior performed by others.

Deindividuation – The replacement of one’s personal identity by identification with the group’s values and goals.

Deinstitutionalization – The process of returning previously hospitalized patients to their communities for treatment of psychological problems and mental disorders.

Delta Activity – The rhythmical activity of the electroencephalogram, having a frequency of less than 3.5 Hz, indicating deep (slow-wave) sleep.

Delusions of Control – The false belief that one’s thoughts and actions are being controlled by other people or forces.

Delusions of Grandeur – The false belief that one is famous, powerful, or important.

Delusions of Persecution – The false belief that other people are plotting against one; symptom of schizophrenia.

Dendrite – A treelike part of a neuron on which the terminal buttons of other neurons form synapses.

Dependent Variable – The event whose value is measured in an experiment. Manipulation of independent variables demonstrates whether they affect the value of dependent variables.

Descriptive Statistics – Mathematical procedures for organizing collections of data, such as determining the mean, the median, the range, the variance, and the correlation coefficient.

Detector – In a regulatory process, a mechanism that signals when the system variable deviates from its set point.

Deuteranopia – A form of hereditary anomalous color vision; caused by defective “green” cones in the retina.

Developmental Approach – An approach to the study of intelligence that studies the way infants and children learn to perceive, manipulate, and think about the world.

Developmental Psychology – The branch of psychology that studies the changes in behavioral, perceptual, and cognitive capacities of organisms as a function of age and experience.

Deviation IQ – A procedure for computing the intelligence quotient; compares a child’s score with those received by other children of the same chronological age.

Diagnostic and Statistical Manual IV (DSM-IV) – A widely used manual for classifying psychological disorders.

Diathesis-Stress Model – A causal account of mental disorders based on the idea that mental disorders develop when a person possesses a predisposition for a disorder, acquired through genetics and early learning experiences, and faces stressors that exceed his or her abilities to cope with them.

Dichotic Listening – A task that requires a person to attend to one of two different messages being presented simultaneously, one to each ear, through headphones.

Diffusion of Responsibility – An explanation of the failure of bystander intervention stating that when several bystanders are present, no one person assumes responsibility for helping.

Direct Dyslexia – A language disorder caused by brain damage in which people can read words aloud without understanding them.

Discrimination – In classical conditioning, the appearance of a CR when one stimulus is presented (the CS+) but not another (the CS-). In operant conditioning, responding only when a specific discriminative stimulus is present but not when similar stimuli are present. In social psychology, the differential treatment of people based on their membership in a particular group.

Discriminative Stimulus – In operant conditioning, the stimulus that sets the occasion for responding because, in the past, a behavior has produced certain consequences in the presence of that stimulus.

Disorganized Schizophrenia – A type of schizophrenia characterized primarily by disturbances of thought and a flattened or silly affect.

Display Rule – A culturally determined rule that prescribes the expression of emotions in particular situations.

Dispositional Factors – Individual personality characteristics that affect a person’s behavior.

Dissociative Disorders – A class of disorders in which anxiety is reduced by a sudden disruption in consciousness, which in turn produces changes in one’s sense of identity.

Distinctive Feature – A physical characteristic of an object that helps distinguish it from other objects.

Distinctiveness – The extent to which a person engages in a particular behavior in one situation but not in others.

DNA – Deoxyribonucleic acid, the structure of chromosomes. DNA structure resembles that of a twisted ladder. Strands of sugar and phosphates are connected by rungs made from adenine and thymine and guanine and cytosine.

Doctrine of Specific Nerve Energies – Johannes Müller’s observation that different nerve fibers convey specific information from one part of the body to the brain or from the brain to one part of the body.

Dominant Allele – The form of the gene that controls the expression of a trait. When a gene pair contains two dominant alleles or when it contains both a dominant and recessive allele, the trait regulated by the dominant gene will be expressed.

Dopamine Hypothesis – The hypothesis that the positive symptoms of schizophrenia are caused by overactivity of synapses in the brain that use dopamine.

Double-Bind – The conflict caused for a child when he or she is given inconsistent messages or cues from a parent.

Double-Blind Study – An experiment in which neither the subjects nor the experimenter knows the value of the independent variable.

Down Syndrome – A genetic disorder caused by a chromosomal aberration resulting in an extra 21st chromosome. People with Down syndrome are generally short with broad skulls and round faces, and suffer impairments in physical, psychomotor, and cognitive development.

Drive – A condition, often caused by physiological changes or homeostatic disequilibrium, that energizes an organism’s behavior.

Drive Reduction Hypothesis – The hypothesis that a drive (resulting from physiological need or deprivation) produces an unpleasant state that causes an organism to engage in motivated behaviors. Reduction of drive is assumed to be reinforcing.

Dualism – The philosophical belief that humans consist of physical bodies and nonmaterial minds or souls.

Echoic Memory – A form of sensory memory for sounds that have just been perceived.

Eclectic Approach – A form of therapy in which the therapist uses whatever method he or she feels will work best for a particular client at a particular time.

Effortful Processing – Practicing or rehearsing information through either shallow or deep processing.

Ego – The self. The ego also serves as the general manager of personality, making decisions regarding the pleasures that will be pursued at the id’s request and the moral dictates of the superego that will be followed.

Egocentrism – Self-centeredness; preoperational children can see the world only from their own perspective.

Ego-Ideal – The internalization of what a person would like to be; his or her goals and ambitions.

Elaboration Likelihood Model – A model that explains the effectiveness of persuasion. The central route requires a person to think critically about an argument and the peripheral route entails the association of the argument with a positive stimulus.

Elaborative Rehearsal – The processing of information on a meaningful level, such as forming associations, attending to the meaning of the material, thinking about it, and so on.

Electrocardiogram (EKG) – The measurement and graphical presentation of the electrical activity of the heart, recorded by means of electrodes attached to the skin.

Electroconvulsive Therapy (ECT) – Treatment of severe depression that involves passing small amounts of electric current through the brain to produce seizure activity.

Electroencephalogram (EEG) – The measurement and graphical presentation of the electrical activity of the brain, recorded by means of electrodes attached to the scalp.

Electromyogram (EMG) – The measurement and graphical presentation of the electrical activity of muscles, recorded by means of electrodes attached to the skin above them.

Electro-Oculogram (EOG) – The measurement and graphical presentation of the electrical activity caused by movements of the eye, recorded by means of electrodes attached to the skin adjacent to the eye.

Elevation – A monocular cue of depth perception; objects nearer the horizon are seen as farther from the viewer.

Embryo Stage – The second stage of prenatal development beginning 2 weeks and ending about 8 weeks after conception, during which the heart begins to beat, the brain starts to function, and most of the major body structures begin to form.

Emotion A relatively brief display of a feeling made in response to environmental events having motivational significance or to memories of such events.

Emotional Stability – The tendency to be relaxed and at peace with oneself.

Emotion-Focused Coping – Any coping behavior that is directed toward changing one’s own emotional reaction to a stressor.

Empiricism – The philosophical view that all knowledge is obtained through the senses.

Encephalization – Increases in brain size.

Encoding Specificity – The principle that how we encode information determines our ability to retrieve it later.

Encoding – The process by which sensory information is converted into a form that can be used by the brain’s memory system.

Endocrine Gland – A gland that secretes a hormone.

Enzymes – Proteins that regulate the structure of bodily cells and the processes occurring within those cells.

Episodic Memory – A type of long-term memory that serves as a record of our life’s experiences.

Escape Response – An operant response acquired through negative reinforcement that terminates an aversive stimulus.

Estrous Cycle – The ovulatory cycle in mammals other than primates; the sequence of physical and hormonal changes that accompany the ripening and disintegration of ova.

Ethnocentrism – The idea that one’s own cultural, national, racial, or religious group is superior to or more deserving than others.

Evolutionary Psychology – The branch of psychology that studies the ways in which an organism’s evolutionary history contributes to the development of behavioral patterns and cognitive strategies related to reproduction and survival during its lifetime.

Exemplar – A memory of particular examples of objects or situations that are used as the basis of classifying objects or situations into concepts.

Expectancy – The belief that a certain consequence will follow a certain action.

Experiential Intelligence – According to Sternberg, the ability to deal effectively with novel situations and to automatically solve problems that have been encountered previously.

Experiment – A study in which the experimenter changes the value of an independent variable and observes whether the manipulation affects the value of a dependent variable. Only experiments can confirm the existence of cause-and-effect relations among variables.

Experimental Ablation – The removal or destruction of a portion of the brain of an experimental animal for the purpose of studying the functions of that region.

Experimental Group – A group of subjects in an experiment, the members of which are exposed to a particular value of the independent variable, which has been manipulated by the experimenter.

Experimental Neuropsychology – The branch of psychology that attempts to understand human brain functions by studying patients whose brains have been damaged through accident or disease.

Explicit Memory – Memory that can be described verbally and of which a person is therefore aware.

Expressed Emotion – Expressions of criticism, hostility, and emotional overinvolvement by family members toward a person with schizophrenia.

Extinction – The elimination of a response that occurs when the CS is repeatedly presented without being followed by the US (classical conditioning) or when the response is not followed by the reinforcer (operant conditioning).

Extraversion – The tendency to seek the company of other people, to be lively, and to engage in conversation and other social behaviors with them.

Eye Tracker – A device that measures the location of a person’s gaze while he or she observes a visual display.

Factor Analysis – A statistical procedure that identifies common factors among groups of tests.

False Consensus – The tendency of a person to perceive his or her own views as representative of a general consensus.

Fetal Alcohol Syndrome – A disorder that adversely affects an offspring’s brain development that is caused by the mother’s alcohol intake during pregnancy.

Fetal Stage – The third and final stage of prenatal development, which lasts for about 7 months, beginning with the appearance of bone tissue and ending with birth.

Fetish – Unusual sexual attachment to objects such as articles of clothing, learned through classical conditioning.

Fight-or-Flight Response – Physiological reactions that help ready us to fight or to flee a dangerous situation.

Figure – A visual stimulus that is perceived as a self-contained object.

Five-Factor Model – A theory stating that personality is composed of five primary dimensions: neuroticism, extraversion, openness, agreeableness, and conscientiousness. This theory was developed using factor analyses of ratings of the words people use to describe personality characteristics.

Fixation – A brief interval between saccadic eye movements during which the eye does not move; visual information is gathered during this time. In Freud’s view, an unconscious obsession with an erogenous zone resulting from failure to resolve the crisis associated with the corresponding stage of psychosexual development.

Fixed-Interval Schedule – A schedule of reinforcement in which the first response that is made after a fixed interval of time since the previous reinforcement (or the start of the session) is reinforced.

Fixed-Ratio Schedule – A schedule of reinforcement in which reinforcement occurs only after a fixed number of responses have been made since the previous reinforcement (or the start of the session).

Flashbulb Memory – A lucid memory for an event or experience that occurred during a particularly emotional experience.

Form Constancy The tendency to perceive objects as having a constant form, even when they are rotated or their distance from the observer changes.

Formal Concept – A category of objects or situations defined by listing their common essential characteristics, as dictionary definitions do.

Fovea – A small pit near the center of the retina containing densely packed cones; responsible for the most acute and detailed vision.

Free Association – A psychoanalytic procedure in which the client is encouraged to speak freely, without censoring possibly embarrassing or socially unacceptable thoughts or ideas.

Free Nerve Ending – An unencapsulated (naked) dendrite of somatosensory neurons.

Frontal Lobe – The front portion of the cerebral cortex, including Broca’s speech area and the motor cortex; damage impairs movement, planning, and flexibility in behavioral strategies.

Function Word – A preposition, article, or other word that conveys little of the meaning of a sentence but is important in specifying its grammatical structure. See also content word.

Functionalism – The strategy of understanding a species’ structural or behavioral features by attempting to establish their usefulness with respect to survival and reproductive success.

Fundamental Attribution Error – The tendency to overestimate the significance of dispositional factors and underestimate the significance of situational factors in explaining other people’s behavior.

Fundamental Frequency – The lowest, and usually most intense, frequency of a complex sound; most often perceived as the sound’s basic pitch.

g factor – According to Spearman, a factor of intelligence that is common to all intellectual tasks; includes apprehension of experience, eduction of relations, and eduction of correlates.

Ganglion Cell – A neuron in the retina that receives information from photoreceptors by means of bipolar cells, and from which axons proceed through the optic nerves to the brain.

Gender Identity – One’s private sense of being male or female.

Gender Role – Cultural expectations about the ways in which men and women should think and behave.

Gender Stereotypes – Beliefs about differences in the behaviors, abilities, and personality traits of males and females.

General Adaptation Syndrome (GAS) – The model proposed by Selye to describe the body’s adaptation to chronic exposure to severe stressors. The body passes through an orderly sequence of three physiological stages: alarm, resistance, and exhaustion.

Generalization – In classical conditioning, CRs elicited by stimuli that resemble the CS used in training. In operant conditioning, the occurrence of responding when a stimulus similar (but not identical) to the discriminative stimulus is present.

Genes – Small units of chromosomes that direct the synthesis of proteins and enzymes.

Genetic Counseling – A form of counseling in which people receive information regarding their family history of genetic disorders and the liklihood that they or their children may have a genetic disorder.

Genetics – The study of the genetic makeup of organisms and how it influences their physical and behavioral characteristics.

Genital Stage – The final of Freud’s psychosexual stages, during which the adolescent develops adult sexual desires.

Genotype – An organism’s genetic makeup.

Gestalt Psychology – A movement is psychology that emphasized that cognitive processes could be understood by studying their organization, not their elements.

Gestalt Therapy – A form of therapy emphasizing the unity of mind and body by teaching the client to “get in touch” with unconscious bodily sensations and emotional feelings.

Glial Cell – A cell of the central nervous system that provides support for neurons and supplies them with some essential chemicals.

Glucocorticoid – A chemical, such as cortisol, that influences the metabolism of glucose, the main energy source of the body.

Glucostatic Hypothesis – The hypothesis that hunger is caused by a low level or availability of glucose, a condition that is monitored by specialized sensory neurons.

Glycogen – An insoluble carbohydrate that can be synthesized from glucose or converted to it; used to store nutrients.

Good Continuation – A Gestalt law of organization; given two or more interpretations of elements that form the outline of the figure, the simplest interpretation will be preferred.

Gray Matter – The portions of the central nervous system that are abundant in cell bodies of neurons rather than axons.

Ground – A visual stimulus that is perceived as a formless background against which objects are seen.

Group – A collection of individuals who generally have common interests and goals.

Group Polarization – The tendency for the initial decision of a group to become exaggerated during the discussion preceding a decision.

Group Psychotherapy – Therapy in which two or more clients meet simultaneously with a therapist, discussing problems within a supportive and understanding environment.

Groupthink – The tendency to avoid dissent in the attempt to achieve group consensus in the course of decision making.

Gustation – The sense of taste.

Habituation – The simplest form of learning; learning not to respond to an unimportant event that occurs repeatedly.

Hallucinations – Perceptual experiences that occur in the absence of external stimulation of the corresponding sensory organ.

Haze – A monocular cue of depth perception; objects that are less distinct in their outline and texture are seen as farther from the viewer.

Health Psychology – The branch of psychology involved in the promotion and maintenance of sound health practices.

Heredity – The sum of the traits and tendencies inherited from a person’s parents and other biological ancestors.

Heritability – The amount of variability in a given trait in a given population at a given time due to genetic factors.

Hertz (Hz) – The primary measure of the frequency of vibration of sound waves; cycles per second.

Heuristics – A general rule that guides decision making.

Hippocampus – A structure in the limbic system, located deep in the temporal lobe, which plays an important role in memory.

Homeostasis – The process by which important physiological characteristics (such as body temperature and blood pressure) are regulated so that they remain at their optimum level.

Hormone – A chemical substance secreted by an endocrine gland that has physiological effects on target cells in other organs.

Hue – A perceptual dimension of color, most closely related to the wavelength of a pure light. The effect of a particular hue is caused by the mixture of lights of various wavelengths.

Humanistic Psychology – An approach to the study of human behavior that emphasizes human experience, choice and creativity, self-realization, and positive growth.

Humanistic Therapy – A form of therapy focusing on the person’s unique potential for personal growth and self-actualization.

Huntington’s Chorea – A genetic disorder caused by a dominant lethal gene in which a person experiences slow but progressive mental and physical deterioration.

Hypochondriasis – A somatoform disorder involving persistent and excessive worry about developing a serious illness. People with this disorder often misinterpret the appearance of normal physical aches and pains.

Hypothalamus – A region of the brain located just above the pituitary gland; controls the autonomic nervous system and many behaviors related to regulation and survival, such as eating, drinking, fighting, shivering, and sweating.

Hypothesis – A statement, usually designed to be tested by an experiment, that tentatively expresses a cause-and-effect relationship between variables.

Iconic Memory – A form of sensory memory that holds a brief visual image of a scene that has just been perceived.

Id – The unconscious reservoir of libido; the psychic energy that fuels instincts and psychic processes.

Illusion of Out-Group Homogeneity – A belief that members of groups to which one does not belong are very similar to one another.

Illusory Correlation – An apparent correlation between two distinctive elements that does not actually exist.

Immune System – A network of organs and cells that protects the body from invading bacteria, viruses, and other foreign substances.

Immunoglobulins – The antibodies that are released by B lymphocytes.

Implicit Memory – Memory that cannot be described verbally and of which a person is therefore not aware.

Implosion Therapy – A form of therapy that attempts to rid people of fears by arousing them intensely until their responses diminish through habituation and learn that nothing bad happens.

Impression Formation – The way in which we form impressions of others and attribute specific characteristics and traits to them.

Incest – The mating of close relatives who share many of the same genes.

Inclusive Fitness – The reproductive success of those who share common genes.

Incongruence – In Rogers’s view, discrepancy between a client’s real and ideal selves.

Independent Variable – The variable that is manipulated in an experiment as a means of determining cause-and-effect relations. Manipulation of an independent variable demonstrates whether it affects the value of the dependent variable.

Indigenous Healing – Non-Western, culture-bound approaches to the treatment of psychological and medical problems.

Inductive Reasoning – Inferring general principles or rules from specific facts.

Inferential Statistics – Mathematical procedures for determining whether relations or differences between samples are statistically significant.

Inflection – A change in the form of a word (usually by adding a suffix) to denote a grammatical feature such as tense or number.

Information Processing – An approach used by cognitive psychologists to explain the workings of the brain; information received through the senses is processed by systems of neurons in the brain.

Informed Consent – Agreement to participate as a subject in an experiment after being informed about the nature of the research and any possible adverse effects.

Intelligence – A person’s ability to learn and remember information, to recognize concepts and their relations, and to apply the information to their own behavior in an adaptive way.

Intelligence Quotient (IQ) – A simplified single measure of general intelligence; by definition, the ratio of a person’s mental age to his or her chronological age, multiplied by 100; often derived by other formulas.

Intermittent Reinforcement – The occasional reinforcement of a particular behavior; produces responding that is more resistant to extinction.

Interneuron – A neuron located entirely within the central nervous system.

Interpersonal Attraction – People’s tendency to approach each other and to evaluate each other positively.

Interposition – A monocular cue of depth perception; an object that partially occludes another object is perceived as closer.

Interrater Reliability – The degree to which two or more independent observers agree in their ratings of another organism’s behavior.

Intraspecific aggression – The attack by one animal upon another member of its species.

Introspection Literally, “looking within,” in an attempt to describe one’s own memories, perceptions, cognitive processes, or motivations.

Introversion – The tendency to avoid the company of other people, especially large groups of people; shyness.

Ion – A positively or negatively charged particle; produced when many substances dissolve in water.

Ion Channel – A special protein molecule located in the membrane of a cell; controls the entry or exit of particular ions.

Ion Transporter – A special protein molecule located in the membrane of a cell; actively transports ions into or out of the cell.

Iris – The pigmented muscle of the eye that controls the size of the pupil.

Isolation Aphasia – A language disturbance that includes an inability to comprehend speech or to produce meaningful speech without affecting the ability to repeat speech and to learn new sequences of words; caused by damage that isolates the brain’s speech mechanisms from other parts of the brain.

James-Lange Theory – A theory of emotion that suggests that behaviors and physiological responses are directly elicited by situations and that feelings of emotions are produced by feedback from these behaviors and responses.

Just-Noticeable Difference (jnd) – The smallest difference between two similar stimuli that can be distinguished. Also called difference threshold.

Kin Selection – A type of selection that favors altruistic acts aimed at individuals who share some of the altruist’s genes, such as parents, siblings, grandparents, grandchildren, and under certain conditions, distant relatives.

Language Universal – A characteristic feature found in all natural languages.

Latency Period – The period between the phallic stage and the genital stage during which there are no unconscious sexual urges or intrapsychic conflicts.

Latent Content – The hidden message of a dream, produced by the unconscious.

Law of Closure – A Gestalt law of organization; elements missing from the outline of a figure are “filled in” by the visual system.

Law of Common Fate – A Gestalt law of organization; elements that move together give rise to the perception of a particular figure.

Law of Effect – Thorndike’s observation that stimuli that occur as a consequence of a response can increase or decrease the likelihood of making that response again.

Law of Proximity – A Gestalt law of organization; elements located closest to each other are perceived as belonging to the same figure.

Law of Similarity – A Gestalt law of organization; similar elements are perceived as belonging to the same figure.

Learned Helplessness – A response to exposure to an inescapable aversive stimulus, characterized by reduced ability to learn a solvable avoidance task; thought to play a role in the development of some psychological disturbances.

Learning – An adaptive process in which the tendency to perform a particular behavior is changed by experience.

Lens – The transparent organ situated behind the iris of the eye; helps focus an image on the retina.

Libido – An insistent, instinctual force that is unresponsive to the demands of reality; the primary source of motivation.

Liking – A feeling of personal regard, intimacy, and esteem toward another person.

Limbic Cortex – The cerebral cortex located around the edge of the cerebral hemispheres where they join with the brain stem; part of the limbic system.

Limbic System – A set of interconnected structures of the brain important in emotional and species-typical behavior; includes the amygdala, hippocampus, and limbic cortex.

Linear Perspective – A monocular cue of depth perception; the arrangement or drawing of objects on a flat surface such that parallel lines receding from the viewer are seen to converge at a point on the horizon.

Linguistic Relativity – The hypothesis that the language a person speaks is related to his or her thoughts and perceptions.

Lithium Carbonate – A simple salt effective in treating bipolar disorder.

Locus of Control – An individual’s beliefs that the consequences of his or her actions are controlled by internal person variables or by external environmental variables.

Long-Term Memory – Memory in which information is represented on a permanent or near-permanent basis.

Loving – A combination of liking and a deep sense of attachment to, intimacy with, and caring for another person.

Maintenance Rehearsal – The rote repetition of information; repeating a given item over and over again.

Major Depression – Persistent and severe feelings of sadness and worthlessness accompanied by changes in appetite, sleeping, and behavior.

Mania – Excessive emotional arousal and wild, exuberant, unrealistic activity.

Manifest Content – The apparent story line of a dream.

Marxist guilt – the feeling of remorse, sin, or wrongdoing that relates to one’s acquisition or management of wealth; particularly when this capital-formation has occurred at the expense of others. It typically refers to the feeling of “sin” that some “haves” may feel when they compare themselves to the “have-nots”.

Masking – Attempting to hide the expression of an emotion.

Matching – A systematic selection of subjects in groups in an experiment or (more often) a correlational study to ensure that the mean values of important subject variables of the groups are similar.

Materialism – A philosophical belief that reality can be known only through an understanding of the physical world of which the mind is a part.

Maturation – Any relatively stable change in thought, behavior, or physical growth that is due to the aging process and not to experience.

Mean – A measure of central tendency; the sum of a group of values divided by their number; the arithmetical average.

Means-Ends Analysis – A general heuristic method of problem solving that involves looking for differences between the current state and the goal state and seeking ways to reduce the differences.

Measure of Central Tendency – A statistical measure used to characterize the value of items in a sample of numbers.

Measure of Variability – A statistical measure used to characterize the dispersion in values of items in a sample of numbers.

Median – A measure of central tendency; the midpoint of a group of values arranged numerically.

Medulla – The part of the brain stem closest to the spinal cord; controls vital functions such as heart rate and blood pressure.

Meiosis – The form of cell division by which new sperm and ova are formed. The chromosomes within the cell are randomly rearranged so that new sperm and ova contain 23 individual chromosomes, or half of that found in other cells of the body.

Memory – The cognitive processes of encoding, storing, and retrieving information.

Meninges – The three-layered set of membranes that enclose the brain and spinal cord.

Mental Age – A measure of a person’s intellectual development; the level of intellectual development that could be expected for an average child of a particular age.

Mental Model – A mental construction based on physical reality that is used to solve problems of logical deduction.

Mental Retardation – Mental development that is substantially below normal; often caused by some form of brain damage or abnormal brain development.

Mental Space (M-Space) – A hypothetical construct in Case’s model of cognitive development similar to working memory, whose primary function is to process information from the external world.

Mere Exposure Effect – The formation of a positive attitude toward a person, place, or thing based solely on repeated exposure to that person, place, or thing.

Meta-Analysis – A statistical procedure by which the results of many studies are combined to estimate the magnitude of a particular effect.

Method of Loci – A mnemonic system in which items to be remembered are mentally associated with specific physical locations or landmarks.

Midbrain – The part of the brain stem just anterior to the pons; involved in control of fighting and sexual behavior and in decreased sensitivity to pain during these behaviors.

Minnesota Multiphasic Personality Inventory (MMPI) – An objective test originally designed to distinguish individuals with different psychological problems from normal individuals. It has since become popular as a means of attempting to identify personality characteristics of people in many everyday settings.

Mnemonic System – A special technique or strategy consciously employed in an attempt to improve memory.

Model – A relatively simple system that works on known principles and is able to do at least some of the things that a more complex system can do.

Modulation – An attempt to exaggerate or minimize the expression of an emotion.

Monogamy – The mating of one female and one male.

Mood Disorder – A disorder characterized by significant shifts or disturbances in mood that affect normal perception, thought, and behavior. Mood disorders may be characterized by deep, foreboding depression, or a combination of the depression and euphoria.

Moral Realism – The first stage of Piaget’s model of moral development, which includes egocentrism and blind adherence to rules.

Morality of Cooperation – The second stage of Piaget’s model of moral development, which involves the recognition of rules as social conventions.

Motion Parallax – A cue of depth perception. As we pass by a scene, objects closer to us pass in front of objects farther away.

Motivation – A general term for a group of phenomena that affect the nature, strength, or persistence of an individual’s behavior.

Motor Association Cortex – Those regions of cerebral cortex that control the primary motor cortex; involved in planning and executing behaviors.

Motor Neuron – A neuron whose terminal buttons form synapses with muscle fibers. When an action potential travels down its axon, the associated muscle fibers will twitch.

Multiple Personality Disorder – A rarely seen dissociative disorder in which two or more distinct personalities exist within the same person; each personality dominates in turn.

Muscle Spindle – A muscle fiber that functions as a stretch receptor, arranged parallel to the muscle fibers responsible for contraction of the muscle, thus detecting muscle length.

Mutations – Accidental alterations in the DNA code within a single gene. Mutations can either be spontaneous and occur naturally or be the result of environmental factors such as exposure to high-energy radiation.

Myelin Sheath – The insulating material that encases most large axons.

Narrative – A mnemonic system in which items to be remembered are linked together by a story.

Natural Concept – A category of objects or situations based on people’s perceptions and interactions with things in the world; based on exemplars.

Natural Selection – The tendency of organisms to reproduce differentially, which is caused by behavioral differences among them. Within any given population, some animals (the survivors) will produce more offspring than other animals.

Naturalistic Observation – The observation of the behavior of people or other animals in their natural environments.

Negative Afterimage – The image seen after a portion of the retina is exposed to an intense visual stimulus; a negative afterimage consists of colors complementary to those of the physical stimulus.

Negative Feedback – A process whereby the effect produced by an action serves to diminish or terminate that action. Regulatory systems are characterized by negative feedback loops.

Negative Reinforcement – A consequence that increases the frequency of a response that is regularly and reliably followed by the termination of an aversive stimulus.

Negative Symptoms – Symptoms of schizophrenia that may include the absence of normal behavior, flattened emotion, poverty of speech, lack of initiative and persistence, and social withdrawal.

Nerve – A bundle of nerve fibers that transmit information between the central nervous system and the body’s sense organs, muscles, and glands.

Neural Network – A model of the nervous system based on interconnected networks of elements that have some of the properties of neurons.

Neuromodulator – A substance secreted in the brain that modulates the activity of neurons that contain the appropriate receptor molecules.

Neuron – A nerve cell; consists of a cell body with dendrites and an axon whose branches end in terminal buttons that synapse with muscle fibers, gland cells, or other neurons.

Neuroticism – The tendency to be anxious, worried, and full of guilt.

Neuroticism, Extraversion, and Openness Personality Inventory (NEO-PI) The instrument used to measure the elements described in the five-factor model of personality (neuroticism, extraversion, openness, agreeableness, and conscientiousness).

Nominal Fallacy – The false belief that one has explained the causes of a phenomenon by identifying and naming it; for example, believing that one has explained lazy behavior by attributing it to “laziness.”

Norm – Data concerning comparison groups that permit the score of an individual to be assessed relative to his or her peers.

Object Permanence – The idea that objects do not disappear when they are out of sight.

Objective Personality Tests – Tests for measuring personality that can be scored objectively, such as a multiple-choice or tue/false test.

Observational Learning – Learning through observing the kinds of consequences others (called models) experience as a result of their behavior.

Obsession – An involuntary recurring thought, idea, or image.

Obsessive-Compulsive Disorder – Recurrent, unwanted thoughts or ideas and compelling urges to engage in repetitive ritual-like behavior.

Occipital Lobe – The rearmost portion of the cerebral cortex; contains the primary visual cortex.

Olfaction – The sense of smell.

Olfactory Mucosa – The mucous membrane lining the top of the nasal sinuses; contains the cilia of the olfactory receptors.

Operant Chamber – An apparatus in which an animal’s behavior can be easily observed, manipulated, and automatically recorded. Sometimes called a “Skinner Box.”

Operant Conditioning – A form of learning in which behavior is affected by its consequences. Favorable consequences strengthen the behavior and unfavorable consequences weaken the behavior.

Operational Definition – The definition of a variable in terms of the operations the experimenter performs to measure or manipulate it.

Opioid – A neuromodulator whose action is mimicked by a natural or synthetic opiate, such as opium, morphine, or heroin.

Opponent Process – The representation of colors by the rate of firing of two types of neurons: red/green and yellow/blue.

Optic Disk – A circular structure located at the exit point from the retina of the axons of the ganglion cells that form the optic nerve.

Optimal Level of Skill Performance – According to Fischer’s Skill Model, the brain’s maximal capacity for information processing.

Optimum-Level Hypothesis – The hypothesis that organisms will perform behavior that restores the level of arousal to an optimum level.

Oral Stage – The first of Freud’s psychosexual stage, during which the mouth is the major source of physical pleasure. Early in this stage, the mouth is used for sucking; later in the stage it is used for biting and chewing.

Orbitofrontal Cortex – A region of the prefrontal cortex that plays an important role in recognition of situations that produce emotional responses.

Organizational Effect – An effect of a hormone that usually occurs during prenatal development and produces permanent changes that alter the subsequent development of the organism.

Orienting Response – Any response by which an organism directs appropriate sensory organs (eyes, ears, nose) toward the source of a novel stimulus.

Ossicle – One of the three bones of the middle ear (the hammer, anvil, and stirrup) that transmit acoustical vibrations from the eardrum to the membrane behind the oval window of the cochlea.

Oval Window – An opening in the bone surrounding the cochlea. The stirrup presses against a membrane behind the oval window and transmits sound vibrations into the fluid within the cochlea.

Overextension – The use of a word to denote a larger class of items than is appropriate, for example, referring to the moon as a ball.

Overtone – The frequencies of complex tones that occur at multiples of the fundamental frequency.

Pacinian Corpuscle – A specialized, encapsulated somatosensory nerve ending, which detects mechanical stimuli, especially vibrations.

Panic – A feeling of fear mixed with hopelessness or helplessness.

Panic Disorder – Unpredictable attacks of acute anxiety that are accompanied by high levels of physiological arousal and that last from a few seconds to a few hours.

Papilla – A small bump on the tongue that contains a group of taste buds.

Parallel Processor – A computing device that can perform several operations simultaneously.

Paranoid Schizophrenia – A form of schizophrenia in which the person suffers from delusions of persecution, grandeur, or control.

Parasympathetic Branch – The portion of the autonomic nervous system that activates functions that occur during a relaxed state.

Parental Investment – The resources including time, physical effort, and risks to life that a parent spends in procreation and in the feeding, nurturing, and protecting of the resulting offspring

Parietal Lobe – The region of the cerebral cortex behind the frontal lobe and above the temporal lobe; contains the somatosensory cortex; is involved in spatial perception and memory.

Passionate Love – An emotional, intense desire for sexual union with another person. Sometimes called “romantic love.”

Peg word Method – A mnemonic system in which items to be remembered are associated with a set of mental pegs that one already has in memory, such as key words of a rhyme.

Perception – A rapid, automatic, unconscious process by which we recognize what is represented by the information provided by our sense organs.

Period of Concrete Operations – The third period in Piaget’s theory of cognitive development, during which children come to understand the conservation principle and other concepts, such as categorization.

Period of Formal Operations – The fourth period in Piaget’s theory of cognitive development, during which individuals first become capable of more formal kinds of abstract thinking and hypothetical reasoning.

Peripheral Nervous System – The cranial and spinal nerves; that part of the nervous system peripheral to the brain and spinal cord.

Perseverance – The tendency to continue to perform a behavior even when it is not being reinforced.

Person Variables – Individual differences in cognition, which, according to Mischel, include competencies, encoding strategies and personal constructs, expectancies, subjective values, and self-regulatory systems and plans.

Personality – A particular pattern of behavior and thinking prevailing across time and situations that differentiates one person from another.

Personality Psychology – The branch of psychology that attempts to categorize and understand the causes of individual differences in patterns of behavior.

Personality Trait – An enduring personal characteristic that reveals itself in a particular pattern of behavior in a variety of situations.

Personality Types – Different categories into which personality characteristics can be assigned based on factors such as developmental experiences or physical characteristics.

Phallic Stage – The third of Freud’s psychosexual stage, during which the primary erogenous zone is the genital area. During this time, children become attached to the opposite-sex parent.

Phantom Limb – Sensations that appear to originate in a limb that has been amputated.

Pharmacotherapy – The treatment of psychological problems with chemical agents.

Phenotype – The outward expression of an organism’s genotype; an organism’s physical appearance and behavior.

Phenylketonuria – A genetic disorder caused by a pair of homozygous recessive genes and characterized by the inability to break down phenylalanine, an amino acid found in many high protein foods. The resulting high blood levels of phenylalanine cause mental retardation.

Phi Phenomenon – The perception of movement caused by the turning on of two or more lights, one at a time, in sequence; often used on theater marquees; responsible for the apparent movement of images in movies and television.

Phobia – Unreasonable fear of specific objects or situations, such as insects, animals, or enclosed spaces, learned through classical conditioning.

Phobic Disorder – An unrealistic, excessive fear of a specific class of stimuli that interferes with normal activities. The object of the anxiety is readily identifiable: It may be a snake, an insect, the out-of-doors, or closed spaces.

Phoneme – The minimum unit of sound that conveys meaning in a particular language, such as /p/.

Phonetic Reading – Reading by decoding the phonetic significance of letter strings; “sound reading.”

Phonological Dyslexia – A reading disorder in which people can read familiar words but have difficulty reading unfamiliar words or pronounceable nonwords because they cannot sound out words.

Phonological Short-Term Memory – Short-term memory for verbal information.

Photopigment – A complex molecule found in photoreceptors; when struck by light, it bleaches and stimulates the membrane of the photoreceptor in which it resides.

Photoreceptor – A receptive cell for vision in the retina; a rod or a cone.

Physiological Psychology – The branch of psychology that studies the physiological basis of behavior.

Pituitary Gland – An endocrine gland attached to the hypothalamus at the base of the brain.

Placebo – An inert substance that cannot be distinguished from a real medication by the patient or subject; used as the control substance in a single-blind or double-blind experiment.

Pleasure Principle – The rule that the id obeys: Obtain immediate gratification, whatever form it may take.

Polyandry – The mating of one female with more than one male.

Polygraph – An instrument that records changes in physiological processes such as brain activity, heart rate, and breathing.

Polygynandry – The mating of several females with several males.

Polygyny – The mating of one male with more than one female.

Pons – The part of the brain stem just anterior to the medulla; involved in control of sleep.

Positive Reinforcement – A consequence that increases the frequency of a response that is regularly and reliably followed by an appetitive stimulus.

Positive Symptoms – Symptoms of schizophrenia that may include thought disorder, hallucinations, or delusions.

Postconventional Level – Kohlberg’s third and final level of moral development, in which people come to understand that moral rules include principles that apply across all situations and societies.

Posthypnotic Amnesia – A failure to remember what occurred during hypnosis; induced by suggestions made during hypnosis.

Posthypnotic Suggestibility – The tendency of a person to perform a behavior suggested by the hypnotist some time after the person has left the hypnotic state.

Postsynaptic Neuron – A neuron with which the terminal buttons of another neuron form synapses and that is excited or inhibited by that neuron.

Posttraumatic Stress Disorder – An anxiety disorder in which the individual has feelings of social withdrawal accompanied by untypically low levels of emotion caused by prolonged exposure to a stressor, such as a catastrophe.

Preconventional Level – Kohlberg’s first level of moral development, which bases moral behavior on external sanctions, such as authority and punishment.

Prefrontal Cortex – The anterior part of the frontal lobe; contains the motor association cortex.

Prejudice – An attitude or evaluation, usually negative, toward a group of people defined by their racial, ethnic, or religious heritage or by their gender, occupation, sexual orientation, level of education, place of residence, or membership in a particular group.

Prenatal Period – The nine months between conception and birth. This period is divided into three developmental stages: the zygote, the embryo, and the fetal stages.

Preoperational Period – The second of Piaget’s periods, which represents a 4- to 5-year transitional period between first being able to think symbolically and then being able to think logically. During this stage, children become increasingly capable of speaking meaningful sentences.

Preoptic Area – A region at the base of the brain just in front of the hypothalamus; contains neurons that appear to control the occurrence of slow-wave sleep.

Presynaptic Neuron – A neuron whose terminal buttons form synapses with and excite or inhibit another neuron.

Preventive Psychology – Any attempt to forestall the development of psychological problems by altering the sociocultural variables predictive of psychological distress.

Primacy Effect – The tendency to remember initial information. In the memorization of a list of words, the primacy effect is evidenced by better recall of the words early in the list.

Primary Auditory Cortex – The region of the cerebral cortex that receives information directly from the auditory system; located in the temporal lobes.

Primary Motor Cortex – The region of the cerebral cortex that directly controls the movements of the body; located in the back part of the frontal lobes.

Primary Punisher – A biologically significant aversive stimuli, such as pain.

Primary Reinforcer – A biologically significant appetitive stimulus, such as food or water.

Primary Somatosensory cortex – The region of the cerebral cortex that receives information directly from the somatosensory system (touch, pressure, vibration, pain, and temperature); located in the front part of the parietal lobes.

Primary Visual Cortex – The region of the cerebral cortex that receives information directly from the visual system; located in the occipital lobes.

Proactive Interference – Interference in recall that occurs when previously learned information disrupts our ability to remember newer information.

Problem-Focused Coping – Any coping behavior that is directed at reducing or eliminating a stressor.

Process Schizophrenia – According to Bleuler, a form of schizophrenia characterized by a gradual onset and a poor prognosis.

Progressive Relaxation Technique – A relaxation technique involving three steps: (1) recognizing the body’s signals that indicate the presence of stress; (2) using those signals as a cue to begin relaxing; and (3) relaxing groups of muscles, beginning with those in the head and neck and then those in the arms and legs.

Projection – A defense mechanism in which one’s unacceptable behaviors or thoughts are attributed to someone else.

Projective Personality Tests – Unstructured personality measures in which a person is shown a series of ambiguous stimuli, such as pictures, inkblots, or incomplete drawings. The person is asked to describe what he or she “sees” in each stimulus or to create stories that reflect the theme of the drawing or picture.

Prosody – The use of changes in intonation and emphasis to convey meaning in speech besides that specified by the particular words; an important means of communication of emotion.

Prosopagnosia – A form of visual agnosia characterized by difficulty in the recognition of people’s faces; caused by damage to the visual association cortex.

Protanopia – A form of hereditary anomalous color vision; caused by defective “red” cones in the retina.

Prototype – A hypothetical idealized pattern that resides in the nervous system and is used to perceive objects or shapes by a process of comparison; recognition can occur even when an exact match is not found.

Protoword – A unique string of phonemes that an infant invents and uses as a word.

Proximate Causes – Immediate environmental events and conditions that affect behavior.

Psychoactive Substance Use Disorders – Disorders are characterized by addiction to drugs or by abuse of drugs.

Psychoanalysis – A form of therapy aimed at providing the client insight into his or her unconscious motivations and impulses.

Psychodynamic – A term used to describe the Freudian notion that the mind is in a state of conflict among instincts, reasons, and conscience.

Psychogenic Amnesia – A dissociative disorder characterized by the inability to remember important events or personal information.

Psychogenic Fugue – Amnesia with no apparent organic cause accompanied by a flight away from home.

Psycholinguistics – The branch of psychology devoted to the study of verbal behavior.

Psychology – The scientific study of the causes of behavior; also, the application of the findings of psychological research to the solution of problems.

Psychoneuroimmunology – Study of the interactions between the immune system and behavior as mediated by the nervous system.

Psychophysics – A branch of psychology that measures the quantitative relation between physical stimuli and perceptual experience.

Psychophysiology – The measurement of physiological responses, such as blood pressure and heart rate, to infer changes in internal states, such as emotions.

Psychosurgery – Surgical destruction of brain tissue in the absence of any evidence of disease or damage in an attempt to treat mental disturbances.

Psychoticism – The tendency to be aggressive, egocentric, and antisocial.

Puberty – The period during which the reproductive systems mature, marking the beginning of the transition from childhood to adulthood.

Punishment – A consequence that decreases the frequency of a response that is regularly and reliably followed by an aversive stimulus.

Pure Word Deafness – The ability to hear, to speak, and (usually) to write, without being able to comprehend the meaning of speech; caused by bilateral temporal lobe damage.

Pursuit Movement – The movement that the eyes make to maintain an image upon the fovea.

No Entries for the letter Q

Random Assignment – An assignment of subjects to the various groups of an experiment by random means, thereby ensuring comparable groups.

Range – The difference between the highest score and the lowest score of a sample.

Rapid Eye Movement (REM) Sleep – A period of sleep during which dreaming, rapid eye movements, and muscular paralysis occur and the EEG shows beta activity.

Rational-Emotive Therapy – Therapy based on the belief that psychological problems are caused not by upsetting events but by how people think about them.

Rationalization – A defense mechanism that justifies an unacceptable action with a more acceptable, but false, excuse.

Reaction Formation – A defense mechanism that involves behaving in a way that is the opposite of how one really feels because the true feelings produce anxiety.

Reactive Schizophrenia – According to Bleuler, a form of schizophrenia characterized by rapid onset and brief duration; he assumed the cause was stressful life situations.

Reality Principle – The tendency to satisfy the id’s demands realistically, which almost always involves compromising the demands of the id and superego.

Receiver Operating Characteristic Curve (ROC curve) – A graph of hits and false alarms of subjects under different motivational conditions; indicates people’s ability to detect a particular stimulus.

Recency Effect – The tendency to recall later information. In the memorization of a list of words, the recency effect is evidenced by better recall of the last words in the list.

Receptive Field – That portion of the visual field in which the presentation of visual stimuli will produce an alteration in the firing rate of a particular neuron.

Receptor Cell – A neuron that directly responds to a physical stimulus, such as light, vibrations, or aromatic molecules.

Receptor Molecule – A special protein molecule located in the membrane of the postsynaptic neuron that responds to molecules of the transmitter substance. Receptors such as those that respond to opiates are sometimes found elsewhere on the surface of neurons.

Recessive Allele – The form of the gene that does not influence the expression of a trait unless it is paired with another recessive allele.

Reciprocal Altruism – Altruism in which people behave altruistically toward one another because they are confident that such acts will be reciprocated toward either them or their kin.

Reciprocal Determinism – The idea that behavior, environment, and person variables, such as perception, interact to determine personality.

Reciprocity – The tendency to return, in kind, favors that others have done for us.

Reflex – An automatic response to a stimulus, such as the blink reflex to the sudden approach of an object toward the eyes.

Regulatory Behavior – A behavior that tends to bring physiological conditions back to normal, thus restoring the condition of homeostasis.

Reliability – The repeatability of a measurement; the likelihood that if the measurement was made again it would yield the same value.

REM Sleep Behavior Disorder – A neurological disorder characterized by absence of the paralysis that normally occurs during REM sleep; the patient acts out his or her dreams.

Replication – Repetition of an experiment or observational study to see whether previous results will be obtained.

Representativeness Heuristic – A general rule for decision making through which people classify a person, place, or thing into the category to which it appears to be the most similar.

Repression – The mental force responsible for actively keeping memories, most of which are potentially threatening or anxiety-provoking, from being consciously discovered.

Reproductive Strategies – Different systems of mating and rearing offspring. These include monogamy, polygny, polyandry, and polygamy.

Reproductive Success – The number of viable offspring an individual produces relative to the number of viable offspring produced by other members of the same species.

Resistance – A development during therapy in which the client becomes defensive, unconsciously attempting to halt further insight by censoring his or her true feelings.

Resistant Attachment – A kind of attachment in which infants show mixed reactions to their mothers. They may approach their mothers upon their return but, at the same time, continue to cry or even push their mothers away.

Response Cost – A consequence that decreases the frequency of response that is regularly and reliably followed by the termination of an appetitive stimulus.

Retina – The tissue at the back inside surface of the eye that contains the photoreceptors and associated neurons.

Retinal Disparity – The fact that points on objects located at different distances from the observer will fall on slightly different locations on the two retinas; provides the basis for stereopsis, one of the forms of depth perception.

Retrieval Cues – Contextual variables, including physical objects, suggestions, or other verbal stimuli, that improve the ability to recall information from memory.

Retrieval – The active processes of locating and using stored information.

Retroactive Interference – Interference in recall that occurs when recently learned information disrupts our ability to remember older information.

Retrograde Amnesia – The loss of the ability to retrieve memories of one’s past, particularly memories episodic or autobiographical events.

Retrospective Study – A research technique that requires subjects to report what happened in the past.

Reuptake – The process by which a terminal button retrieves the molecules of transmitter substance that it has just released; terminates the effect of the transmitter substance on the receptors of the postsynaptic neuron.

Rhodopsin – The photopigment contained by rods.

Rod – A photoreceptor that is very sensitive to light but cannot detect changes in hue.

Rorschach Inkblot Test – A projective test in which a person is shown a series of symmetrical inkblots and asked to describe what he or she thinks they represent.

Round Window – An opening in the bone surrounding the cochlea. Movements of the membrane behind this opening permit vibrations to be transmitted through the oval window into the cochlea.

s factor – According to Spearman, a factor of intelligence that is specific to a particular task.

Saccadic Movement – The rapid movement of the eyes that is used in scanning a visual scene, as opposed to the smooth pursuit movements used to follow a moving object.

Sample – A selection of items from a larger population-for example; a group of subjects selected to participate in an experiment.

Saturation – A perceptual dimension of color, most closely associated with purity of a color.

Scatterplot – A graph of items that have two values; one value is plotted against the horizontal axis and the other against the vertical axis.

Schema – A mental framework or body of knowledge that organizes and synthesizes information about a person, place, or thing. The plural form of this term is “schemata.”

Schizophrenia – A serious mental disorder characterized by thought disturbances, hallucinations, anxiety, emotional withdrawal, and delusions.

Scientific Method – A set of rules that govern the collection and analysis of data gained through observational studies or experiments.

Sclera – The tough outer layer of the eye; the “white” of the eye.

Script – The characteristics (events, rules, and so on) that are typical of a particular situation; assists the comprehension of verbal discourse.

Seasonal Affective Disorder – A mood disorder characterized by depression, lethargy, sleep disturbances, and craving for carbohydrates. This disorder generally occurs during the winter, when the amount of daylight, relative to the other seasons, is low. This disorder can be treated with exposure to bright lights.

Secure Attachment – A kind of attachment in which infants use their mothers as a base for exploring a new environment. They will venture out from their mothers to explore a Strange Situation but return periodically.

Selective Attention – The process that controls our awareness of, and readiness to respond to, particular categories of stimuli or stimuli in a particular location.

Self – A person’s distinct individuality.

Self-Actualization – The realization of one’s true intellectual and emotional potential.

Self-Attribution – Attributions made about the causes of our behavior based on our self-observations of the way we act in different situations.

Self-Concept – Self-identity. One’s knowledge, feelings, and ideas about oneself.

Self-Control – Behavior that produces the larger, longer-term reward when people are faced with the choice between it and the smaller, short-term reward.

Self-Efficacy – The expectation of success; the belief in one’s own competencies.

Self-Fulfilling Prophecy – A stereotype that causes a person to act in a manner consistent with that stereotype.

Self-Perception Theory – The theory that we come to understand our attitudes and emotions by observing our own behavior and the circumstances under which it occurs.

Self-Schema – A mental framework that represents and synthesizes information about oneself; a cognitive structure that organizes the knowledge, feelings, and ideas that constitute the self-concept.

Self-Serving Bias – The tendency to attribute our accomplishments and successes to internal causes and our failures and mistakes to external causes.

Semantic Memory – A type of long-term memory that contains data, facts, and other information, including vocabulary.

Semantic Priming – A facilitating effect on the recognition of words having meanings related to a word that was presented previously.

Semantics – The meanings and the study of the meanings represented by words.

Semicircular Canal – One of a set of three receptor organs in the inner ear that respond to rotational movements of the head.

Sensation – The detection of the elementary properties of a stimulus.

Sensorimotor Period – The first period in Piaget’s theory of cognitive development, from birth to 2 years. Marked by an orderly progression of increasingly complex cognitive development: reflexes, permanence, appreciation of causality, imitation, and symbolic thinking.

Sensory Association Cortex – Those regions of cerebral cortex that receive information from the primary sensory areas.

Sensory Memory – Memory in which representations of the physical features of a stimulus are stored for very brief durations.

Sensory Neuron – A neuron that detects changes in the external or internal environment and sends information about these changes to the central nervous system.

Separation Anxiety – A set of fearful responses, such as crying, arousal, and clinging to the caregiver, that infants exhibit when the caregiver attempts to leave the infant.

Serum Cholesterol – A fatlike chemical found in the blood. One form (LDL) promotes the formation of atherosclerotic plaques. Another form (HDL) may protect against coronary heart disease.

Set Point – The optimum value of the system variable in a regulatory mechanism. The set point for human body temperature, recorded orally, is approximately 98.6°F.

Sex Chromosomes – The chromosomes that contain the instructional code for the development of male or female sex characteristics.

Sexual Selection – Selection for traits specific to gender, such as body size or particular patterns of behavior.

Shading – A monocular cue of depth perception; determines whether portions of the surface of an object are perceived as concave or convex.

Shadowing – The act of continuously repeating verbal material as soon as it is heard.

Shallow Processing – The analysis of the superficial characteristics of a stimulus, such as its size or shape.

Shaping – The reinforcement of behavior that successively approximates the desired response until that response is fully acquired.

Short-Term Memory – An immediate memory for stimuli that have just been perceived. It is limited in terms of both capacity (7 ± 2 chunks of information) and duration. Sometimes called “working memory.”

Signal Detection Theory – A mathematical theory of the detection of stimuli, which involves discriminating a signal from the noise in which it is embedded, and which takes into account the subjects’ willingness to report detecting the signal.

Simple Phobia – An excessive and irrational fear of specific things, such as snakes, darkness, or heights.

Simulation – An attempt to express an emotion that one does not actually feel.

Single-Blind Study – An experiment in which the experimenter but not the subject knows the value of the independent variable.

Single-Subject Research – An experiment or correlational study concerning the behavior of individual subjects rather than comparisons of the average performance of groups of subjects.

Situational Factors – Environmental stimuli that affect a person’s behavior.

Slow-Wave Sleep – Sleep other than REM sleep, characterized by regular, slow waves on the electroencephalograph.

Social Cognition – The processes involved in perceiving, interpreting, and acting on social information.

Social Facilitation – The enhancement of task performance caused by the mere presence of others.

Social Learning Theory – The idea that both consequences of behavior and the individual’s beliefs about those consequences determine personality.

Social Loafing – The decreased effort put forth by individuals when performing a task with other people.

Social Norms – Informal rules defining the expected and appropriate behavior in specific situations.

Social Phobia – A mental disorder characterized by an excessive and irrational fear of situations in which the person is observed by others.

Social Psychology – The branch of psychology that studies our social nature or how the actual, imagined, or implied presence of others influences our thoughts, feelings, and behaviors.

Sociobiology – The study of the biological bases of social behavior.

Soma – A cell body; the largest part of a neuron.

Somatization Disorder – A class of somatoform disorder, occurring mostly among women, that involves complaints of wide-ranging physical ailments for which there is no apparent biological cause.

Somatoform Disorder – A mental disorder involving a bodily or physical problem for which there is no physiological basis.

Somatosense – Bodily sensations; sensitivity to such stimuli as touch, pain, and temperature.

Species-Typical Behavior – A behavior seen in all or most members of a species, such as nest building, special food-getting behaviors, or reproductive behaviors.

Spinal Cord – A long, thin collection of nerve cells attached to the base of the brain and running the length of the spinal column.

Spinal Nerve – A bundle of nerve fibers attached to the spinal cord; conveys sensory information from the body and carries messages to muscles and glands.

Split-Brain Operation – A surgical procedure that severs the corpus callosum, thus abolishing the direct connections between the cortex of the two cerebral hemispheres.

Spontaneous Recovery – After an interval of time, the reappearance of a response that had previously been extinguished.

Standard Deviation – A statistic that expresses the variability of a measurement; square root of the sum of the squared deviations from the mean.

Stanford-Binet Scale – An intelligence test that consists of various tasks grouped according to mental age; provides the standard measure of the intelligence quotient.

State-Dependent Memory – The tendency to recall information better when our mental or emotional state at retrieval matches that during encoding.

Statistical Significance – The likelihood that an observed relation or difference between two variables is not due to chance factors.

Stereopsis – A form of depth perception based on retinal disparity.

Stereotaxic Apparatus – A device used to insert an electrode into a particular part of the brain for the purpose of recording electrical activity, stimulating the brain electrically, or producing localized damage.

Stereotype – An overgeneralized and false belief about the characteristics of members of a particular group.

Stimulus Equivalence – A type of learning in which stimuli become equivalent even though the organism has never observed a relation between them; may be involved in learning how to read and manipulate symbols.

Storage – The process of maintaining information in memory.

Strange Situation – A test of attachment in which an infant is exposed to different stimuli that may be distressful.

Stranger Anxiety – The wariness and fearful responses, such as crying and clinging to their caregivers, that infants exhibit in the presence of strangers.

Stress – A pattern of physiological, behavioral, and cognitive responses to stimuli that are perceived as endangering one’s well-being.

Stress Inoculation Training – A method of teaching people to cope with anticipated problems. It involves three steps: education, rehearsal, and application.

Stressors – Stimuli that are perceived as endangering one’s well-being.

Striving For Superiority – The motivation to seek superiority. Adler argued that striving for superiority is born from our need to compensate for our inferiorities.

Stroke – A cerebrovascular accident; damage to the brain caused by a blood clot in a cerebral artery or rupture of a cerebral blood vessel.

Structural Family Therapy – A form of family therapy in which the maladaptive relationships among family members is inferred from their behavior and attempts are made to restructure these behaviors into more adaptive ones.

Structuralism – Wundt’s system of experimental psychology; it emphasized introspective analysis of sensation and perception.

Sublimation – A defense mechanism that involves redirecting pleasure-seeking or aggressive instincts toward socially acceptable goals.

Subliminal Perception – The perception of a stimulus, as indicated by a change in behavior, at an intensity insufficient to produce a conscious sensation.

Subordinate Concept – A concept that refers to types of items within a basic-level category.

Subvocal Articulation – An unvoiced speech utterance.

Superego – The repository of an individual’s moral values, divided into the conscience, or the internalization of a society’s rules and regulations, and the ego-ideal, or the internalization of one’s goals.

Superordinate Concept – A concept that refers to collections of basic-level concepts.

Superstitious Behavior – A behavior that occurs in response to the regular, noncontingent occurrence of an appetitive stimulus to a motivated organism; appears to cause a certain event, but in reality does not.

Surface Dyslexia – A reading disorder in which people can read words phonetically but have difficulty reading irregularly spelled words by the whole-word method.

Surface Structure – The grammatical features of a sentence. See also deep structure.

Syllogism – A logical construction that contains a major premise, a minor premise, and a conclusion. The major and minor premises are assumed to be true, and the truth of the conclusion is to be evaluated by deductive reasoning.

Sympathetic Branch – The portion of the autonomic nervous system that activates functions that accompany arousal and expenditure of energy.

Synapse – The junction between the terminal button of one neuron and the membrane of a muscle fiber, a gland, or another neuron.

Synaptic Cleft – A fluid-filled gap between the presynaptic and postsynaptic membranes; the terminal button releases transmitter substance into this space.

Syntactical Rule – A grammatical rule of a particular language for combining words to form phrases, clauses, and sentences.

System Variable – The variable controlled by a regulatory mechanism; for example, temperature in a heating system.

Systematic Sesensitization – A method of treatment in which the client is trained to relax in the presence of increasingly fearful stimuli.

T Lymphocytes – Cells that develop in the thymus gland that produce antibodies, which defend the body against fungi, viruses, and multicellular parasites.

Tachistoscope – A device that can present visual stimuli for controlled (usually very brief) durations of time.

Tardive dyskinesia – A serious movement disorder that can occur when a person has been treated with antipsychotic drugs for an extended period.

Target Cell – A cell whose physiological processes are affected by a particular hormone; contains special receptor molecules that respond to the presence of the hormone.

Taste Bud – A small organ on the tongue that contains a group of gustatory receptor cells.

Tectorial Membrane – A membrane located above the basilar membrane; serves as a shelf against which the cilia of the auditory hair cells move.

Template – A hypothetical pattern that resides in the nervous system and is used to perceive objects or shapes by a process of comparison.

Temporal Coding – A means of representing information by the nervous system; different features are coded by the pattern of activity of neurons.

Temporal Lobe – The portion of the cerebral cortex below the frontal and parietal lobes and containing the auditory cortex.

Teratogens Drugs or other substances that can cause birth defects.

Terminal Button – The rounded swelling at the end of the axon of a neuron; releases transmitter substance.

Texture – A monocular cue of depth perception; the fineness of detail present in the surface of objects or in the ground or floor of a scene.

Thalamus – A region of the brain near the center of the cerebral hemispheres. All sensory information except smell is sent to the thalamus and then relayed to the cerebral cortex.

Thematic Apperception Test (TAT) – A projective test in which a person is shown a series of ambiguous pictures that involve people. The person is asked to make up a story about what the people are doing or thinking. The person’s responses are believed to reflect aspects of his or her personality.

Theory – A set of statements designed to explain a set of phenomena; more encompassing than a hypothesis.

Theta Activity – EEG activity of 3.5-7.5 Hz; occurs during the transition between sleep and wakefulness.

Thought Disorder – A pattern of disorganized, illogical, and irrational thought that often accompanies schizophrenia.

Threat Gesture – A stereotyped gesture that signifies that one animal is likely to attack another member of the species.

Three-Term Contingency – The relation among discriminative stimuli, behavior, and the consequences of that behavior. A motivated organism emits a specific response in presence of a discriminative stimulus because in the past, that response has been reinforced only when the discriminative stimulus is present.

Threshold – The point at which a stimulus, or a change in the value of a stimulus, can just be detected.

Timbre – A perceptual dimension of sound, determined by the complexity of the sound; for example, as shown by a mathematical analysis of the sound wave.

Tip of the Tongue Phenomenon – An occasional problem with retrieval of information that we are sure we know but cannot immediately remember.

Token Economy – A program often used in institutions in which a person’s adaptive behavior is reinforced with tokens that are exchangeable for desirable goods or special privileges.

Tolerance – The decreased sensitivity to a drug resulting from its continued use.

Top-Down Processing – A perception based on information provided by the context in which a particular stimulus is encountered.

Tourette’s Syndrome – A neurological disorder characterized by tics and involuntary utterances, some of which may involve obscenities and the repetition of others’ utterances.

Transduction – The conversion of physical stimuli into changes in the activity of receptor cells of sensory organs.

Transference – The process by which a client begins to project powerful attitudes and emotions onto the therapist.

Transmitter Substance – A chemical released by the terminal buttons that causes the postsynaptic neuron to be excited or inhibited.

Trephining – A surgical procedure in which a hole is made in the skull of a living person

Trichromatic Theory – The theory that color vision is accomplished by three types of photodetectors, each of which is maximally sensitive to a different wavelength of light.

Tritanopia – A form of hereditary anomalous color vision; caused by a lack of “blue” cones in the retina.

Two-Point Discrimination Threshold – The minimum distance between two small points that can be detected as separate stimuli when pressed against a particular region of the skin.

Type A Pattern – A behavior pattern characterized by high levels of competitiveness and hostility, impatience, and an intense disposition; supposedly associated with an increased risk of CHD.

Type B Pattern – A behavior pattern characterized by lower levels of competitiveness and hostility, patience, and an easygoing disposition; supposedly associated with a decreased risk of CHD.

Type C Personality – A behavior pattern characterized by cooperativeness, unassertiveness, patience, suppression of negative emotions, and acceptance of external authority; supposedly associated with an increased likelihood of cancer.

Ultimate Causes – Evolutionary conditions that have slowly shaped the behavior of a species over generations.

Unconditional Positive Regard – Unconditional love and acceptance of an individual by another person.

Unconditional Response – In classical conditioning, a response, such as salivation, that is naturally elicited by the UCS.

Unconditional Stimulus (UCS) – In classical conditioning, a stimulus, such as food, that naturally elicits a reflexive response, such as salivation.

Unconscious – The inaccessible part of the mind.

Underextension – The use of a word to denote a smaller class of items than is appropriate, for example, referring only to one particular animal as a dog.

Undifferentiated Schizophrenia – A type of schizophrenia characterized by fragments of the symptoms of other, different types of schizophrenia.

Validity – The degree to which the operational definition of a variable accurately reflects the variable it is designed to measure or manipulate.

Variable – A measure capable of assuming any of several values.

Variable Errors – An error caused by random differences in experimental conditions, such as the subject’s mood or changes in the environment.

Variable-Interval Schedule – A schedule of reinforcement similar to a fixed-interval schedule but characterized by a variable time requirement with a particular mean.

Variable-Ratio Schedule – A schedule of reinforcement similar to a fixed-ratio schedule but characterized by a variable response requirement with a particular mean.

Variation – The differences found across individuals of any given species in terms of their genetic, biological (size, strength, physiology), and psychological characteristics (intelligence, sociability, behavior).

Vertebra – One of the bones that encase the spinal cord and constitute the vertebral column.

Vestibular Apparatus – The receptive organs of the inner ear that contribute to balance and perception of head movement.

Vestibular Sac – One of a set of two receptor organs in the inner ear that detect changes in the tilt of the head.

Visual Agnosia – The inability of a person, who is not blind, to recognize the identity or use of an object by means of vision; usually caused by damage to the brain.

Voice-Onset Time – The delay between the initial sound of a voiced consonant (such as the puffing sound of the phoneme /p/) and the onset of vibration of the vocal cords.

Wavelength – The distance between adjacent waves of radiant energy; in vision most closely associated with the perceptual dimension of hue.

Weber Fraction – The ratio between a just-noticeable difference and the magnitude of a stimulus; reasonably constant over the middle range of most stimulus intensities.

Wechsler Adult Intelligence Scale (WAIS) – An intelligence test for adults devised by David Wechsler; contains eleven subtests divided into the categories of verbal and performance.

Wechsler Intelligence Scale for Children (WISC) – An intelligence test for children devised by David Wechsler; similar in form to the Wechsler Adult Intelligence Scale.

Wernicke’s Aphasia – A disorder caused by damage to the left temporal and parietal cortex, including Wernicke’s area; characterized by deficits in the perception of speech and by the production of fluent but rather meaningless speech.

Wernicke’s Area – A region of auditory association cortex located in the upper part of the left temporal lobe; involved in the recognition of spoken words.

White Matter – The portions of the central nervous system that are abundant in axons rather than cell bodies of neurons. The color derives from the presence of the axons’ myelin sheaths.

Whole-Word Reading – Reading by recognizing a word as a whole; “sight reading.”

Withdrawal Symptom – An effect produced by discontinuance of use of a drug after a period of continued use; generally opposite to the drug’s primary effects.

Zeitgeber – Any stimulus, such as light, that synchronizes daily biological rhythms.

Zygote stage – The first stage of prenatal development, during which the zygote divides many times and the internal organs begin to form.

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