GLOSSARY

A

Absolute threshold.: The minimal amount of energy necessary to stimulate the sensory receptors.
Action potential.: A momentary electrical event occurring through the membrane of a nerve cell fiber in response to a stimulus, forming a nerve impulse.
Addiction/addictive personality.: A wide spectrum of complex behaviors that arises from dependence on drugs or participation in some other activity.
Adjustment disorders.: The development of significant emotional or behavioral symptoms in response to an identifiable event that precipitated psychological or social stress.
Alcoholic psychoses.: Acute reactions to alcohol characterized by alcohol idiosyncratic intoxication, alcohol withdrawal delirium, hallucinations, and irreversible brain damage involving severe memory loss.
Alexia.: Inability to read; a form of dyslexia.
Ambivalence.: The concurrent existence of contrasting, opposing, or contradictory feelings, emotions, or attitudes regarding a person, object, or idea.
Ames room.: Specially constructed space that demonstrates aspects of visual perception.
Anal stage.: The second stage in Sigmund Freud's theory of psychosexual development characterized by concerns over elimination, usually taking place around two years of age.
Anonymity.: A condition in which the identity of an individual is not known to others.
Anorexia.: An eating disorder in which preoccupation with dieting and thinness leads to excessive and dangerous weight loss.
Anoxia.: Lack of oxygen in the blood supply; also called oxygen starvation.
Antisocial behavior.: A pattern of behavior that is verbally or physically harmful to other people, animals, or property, including behavior that severely violates social expectations.
Antisocial personality disorder.: A behavior disorder characterized by disregard for social norms and laws, manipulation, impulsivity, recklessness, and lack of remorse; also known as sociopathy or psychopathy.
Anxiety/anxiety disorders.: An unpleasant emotional state characterized by apprehension, worry, and fear.
Apgar score.: The sum of numerical results indicating a newborn infant's overall medical condition.
Aphasia.: A condition in which a person's previous capacity to understand or express language is impaired.
Archetype.: Primordial images and symbols found in the collective unconscious that are passed on from generation to generation.
Arousal.: An increase in the level of an individual's readiness for activity.
Associationism.: The view that mental processes can be explained in terms of the association of ideas.
Attention deficit/hyperactivity disorder (ADHD).: Disorder characterized by inattention, impulsivity, and hyperactivity.
Attribution theory.: A term used to describe how people explain the causes of behavior, both their own and those of others.
Authoritarian personality.: A personality pattern characterized by rigidity, dependence on authority, conformity to group values, and intolerance of ambiguity.
Autoeroticism.: Commonly referred to as masturbation, self-stimulation of the genital organs with the intention of producing sexual arousal and orgasm.
Autohypnosis.: The ability to hypnotize oneself without the aid of another person.

Autonomic nervous system.: The nervous system responsible for regulating automatic bodily processes, such as breathing and heart rate. It also involves the processes of metabolism, or the storage and expenditure of energy.
Aversive conditioning.: Also referred to as aversion therapy, a technique that links undesired behavior with physical or psychological discomfort.
Avoidance learning.: An individual's response to avoid an unpleasant or stressful situation; also known as escape learning.
Avoidant personality.: Personality disorder characterized by social withdrawal and fear of rejection.
Axon.: One of two types of short, threadlike fibers that extend from the cell body of a nerve cell, or neuron (the other type are called dendrites), and which sends electrochemical signals.

B

Battered child syndrome.: A group of physical and mental symptoms arising from long-term physical violence against a child.
Bayley Scales of Infant Development.: A comprehensive developmental test for infants and toddlers from two to 30 months of age.
Behavior modification.: A treatment approach, based on the principles of operant conditioning, that replaces undesirable behaviors with more desirable ones through reinforcements.
Behavior therapy.: A goal-oriented, therapeutic approach that treats disorders as maladaptive learned responses that can be replaced by healthier ones.
Behaviorism.: A theory of human development initiated by Edward Thorndike and developed by John Watson and B.F. Skinner, emphasizing the study of measurable and observable behavior.
Bender-Gestalt test.: Diagnostic assessment test to identify learning disability, neurological disorders, and developmental delay.
Bestiality.: Sexual feelings or behaviors involving animals; also referred to as zoophilia.
Binocular depth cues.: Properties of the visual system that facilitate depth perception by the nature of messages that are sent to the brain.
Bipolar disorder.: A condition traditionally called manic depression in which a person alternates between the two emotional extremes of depression and mania.
Borderline personality.: Mental illness characterized by erratic and impulsive self-destructive behavior and an intense fear of abandonment.
Bowen theory.: An approach to family therapy proposed by Murray Bowen in which family members are taught to reestablish their "real" identities.
Brainstem.: Connector between the brain and the spinal cord.
Brief reactive psychosis.: An uncommon acute mental disorder precipitated by an event that causes intense psychological stress.
Broca's aphasia.: Type of aphasia characterized by slow, labored, "telegraphic" speech with propositions and articles missing.
Bulimia.: Eating disorder marked by episodes of binge eating followed by behaviors to control weight.
Bystander effect.: The effect of the presence of others on an individual's perception of and response to a situation.

C

Castration anxiety.: The fear of losing one's penis. In Freudian terms, this fear causes the boy to abandon his incestuous attachment to his mother and begin to identify with his father.
Catharsis.: The release of repressed psychic energy.
Cathexis.: The investment of psychic energy in a person or object connected with the gratification of instincts.
Central nervous system.: The portion of the nervous system that lies within the brain and spinal cord; it receives impulses from nerve cells throughout the body, regulates bodily functions, and directs behavior.
Cerebellum.: Located below the cerebrum and behind the brainstem, it controls subconscious activities, such as balance and muscular coordination.
Cerebral cortex.: Cerebrum's outer layer consisting of nerve cell bodies.
Cerebral palsy.: A permanent motor disability caused by brain damage associated with birth.
Cerebrum.: Divided into two hemispheres (left and right), the part of the brain that interprets sensory impulses. The left side functions mainly in speech, logic, writing, and arithmetic. The right side is linked with imagination, art, symbols, and spatial relations.

Childhood amnesia.: The common inability to recall childhood experiences during the first three to five years of life.
Classical conditioning.: The process of closely associating a neutral stimulus with one that evokes a reflexive response so that eventually the neutral stimulus alone will evoke the same response.
Clinical psychology.: The application of psychological principles to diagnosing and treating persons with emotional and behavioral problems.
Codependence.: A term used to describe a person who is intimately involved with a person who is abusing or addicted to alcohol or another substance.
Cognition.: A general term for the higher mental processes by which people acquire knowledge, solve problems, and plan for the future.
Cognitive behavior therapy.: A therapeutic approach based on the principle that maladaptive moods and behavior can be changed by replacing distorted or inappropriate ways of thinking with thought patterns that are healthier and more realistic.
Cognitive dissonance.: Inconsistency between attitude (or belief) and behavior.
Cognitive psychology.: An approach to psychology that focuses on the relationship between cognitive or mental processes and behavior.
Cognitive restructuring.: Process of replacing negative thoughts with alternative thoughts that are positive and calming.
Collective unconscious.: Consciousness that is shared by all people regardless of generation or culture.
Combat neurosis.: Mental disturbances related to the stress of military combat.
Comparative psychology.: A subfield of experimental psychology that focuses on the study of animals for the purpose of comparing the behavior of different species.
Compensation.: A defense mechanism in which an individual unconsciously develops or overdevelops one area of personality as substitutive behavior to make up for a deficiency or inferiority in another area.
Concept formation.: Learning process by which items are categorized and related to each other.
Concrete operational stage.: Third stage of Jean Piaget's theory of cognitive development. At this stage, children begin to develop clearer methods of thinking, although they have difficulty conceiving abstract thought.
Conditioned response.: Behavior that is learned in response to a particular stimulus.
Conditioned stimulus.: Stimulus that leads to a learned response.
Conduct disorder.: Childhood antisocial behavior disorder characterized by aggressive and destructive actions that harm others or property.
Consciousness.: Awareness of external stimuli and of one's own mental activity.
Convergent thinking.: The ability to narrow the number of possible solutions to a problem by applying logic and knowledge.
Conversion reaction.: A psychological disorder characterized by physical symptoms for which no physiological cause can be found.
Correlational method.: A technique used to measure the likelihood of two behaviors or events relating to each other.
Counterconditioning.: Weakening or eliminating an undesired response by introducing and strengthening a second response that is incompatible with it.
Covert conditioning.: A method for changing behavior that involves the client using imagination to target unwanted behavior.
Cross-cultural psychology.: A subfield of psychology concerned with observing human behavior in contrasting cultures.
Cross-sectional study.: Research that collects data simultaneously from people of different ages.
Cybernetics.: The study of artificial intelligence systems and their comparison to human brain functions.

D

Deductive reasoning.: Way of thinking that relates ideas to one another in reaching conclusions.
Defense mechanisms.: Unconscious strategies for avoiding or reducing threatening feelings such as fear and anxiety.
Delusion.: Beliefs that are in stark contrast to reality, often having to do with persecution or an exaggerated sense of importance or glory.
Dementia.: A gradual deterioration of mental functioning affecting all areas of cognition, including judgment, language, and memory.
Dendrites.: Nerve cell fibers that receive signals from other cells.

Deoxyribonucleic acid (DNA).: An organic substance that encodes and carries genetic information and is the fundamental element of heredity.
Dependent personality disorder.: Disorder characterized by a lack of self-confidence coupled with excessive dependence on others.
Dependent variable.: Variable measured in an experiment or study; what the experimenter measures.
Depression.: An emotional state or mood characterized by one or more of these symptoms: sad mood, low energy, poor concentration, sleep or appetite changes, feelings of worthlessness or hopelessness, and thoughts of suicide.
Derealization.: Type of dissociation in which a person perceives reality in a grossly distorted way.
Desensitization.: Behavioral modification technique in which undesired behavior, such as anxiety, is paired with another response that is incompatible with it, such as relaxation.
Determinism.: A scientific perspective that specifies that events occur in completely predictable ways as a result of natural and physical laws.
Developmental delay.: Any delay in a person's physical, cognitive, behavioral, emotional, or social development, due to any number of reasons.
Developmental psychology.: The study of the ways in which people develop physically, emotionally, intellectually, and socially over the course of their lives.
Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).: A reference work developed by the American Psychiatric Association and designed to provide guidelines for the diagnosis and classification of mental disorders.
Diencephalon.: Located above the brainstem, the site of the thalamus and hypothalamus.
Differential psychology.: The area of psychology concerned with measuring and comparing differences in individual and group behavior.
Displacement.: A defense mechanism in which an unacceptable impulse, such as aggression, is redirected to something more acceptable, such as participating in a boxing match.
Dissociative identity disorder.: A disorder in which a person's identity dissociates, or fragments, creating additional, distinct identities that exist independently of each other within the same person; also known as multiple personality disorder.
Divergent thinking.: The ability to come up with original and unique ideas and to envision multiple solutions to a problem.
Double bind.: Term used to describe situations in which communication and behavior conflict (for example, using warm, comforting voice while administering physical punishment to a child).
Draw-a-person test.: A test that measures nonverbal intelligence or to screen for emotional or behavioral disorders.
Drive reduction theory.: A popular theory of the 1940s and 1950s that attributed behavior to the desire to reduce tension produced by primary (biological) or secondary (acquired) drives.
Dyslexia.: A reading disability that is not caused by an identifiable physical problem.

E

Echolalia.: Repetition of another person's words or phrases.
Ectomorph.: A body type proposed by William Sheldon, who characterized ectomorphs as thin and intellectual or artistic.
Effector.: Peripheral tissue at the outer end of an efferent neural path (one leading away from the central nervous system).
Ego.: In psychoanalytic theory, the part of human personality that combines innate biological impulses (id) or drives with reality to produce appropriate behavior.
Electroconvulsive therapy (ECT).: Also known as shock therapy, the application of mild electric current to the brain to produce an epileptic-like seizure as a means of treating certain psychological disorders, primarily severe depression.
Electroencephalograph (EEG).: A device used to record the electrical activity of the brain.
Emotional intelligence.: The ability to perceive and constructively act on both one's own emotions and the feelings of others.
Empiricism.: Type of research that is based on direct observation.
Encounter group.: Group of individuals who engage in intensive and psychotherapeutic interaction, with the general intention of increasing awareness of self and sensitivity to others, and improving interpersonal skills.

Endocrine glands.: Ductless glands that secrete hormones into the bloodstream.
Endomorph.: A body type proposed by William Sheldon, who characterized endomorphs as heavy and easy-going.
Enuresis.: Also known as bedwetting, the inability to control urination during periods of sleep.
Equilibrium sense.: One of two proprioceptive sensory systems that provide input about the positions of one's body.
Ethology.: The study of animal behavior as observed in the natural environment and in the context of evolutionary adaptation.
Etiology.: The study of how and why diseases or disorders originate.
Eugenics.: The systematic attempt to increase desirable genetic traits and to decrease undesirable ones in a population.
Experimental design.: Careful and detailed plan of an experiment.
Experimenter bias.: The subtle and unintentional influence of the experimenter on the subjects in an experiment.
Exposure-response prevention.: A behavioral treatment technique in which a person is exposed to an anxiety-producing event and kept from responding in an undesirable manner.
Extinction.: The elimination of a conditioned response by withholding reinforcement.

F

Failure to thrive.: Failure of an infant, toddler, or child to grow at a normal rate.
Familial retardation.: Mild mental retardation attributed to environmental causes and generally involving some degree of psychosocial disadvantage.
Family therapy.: The joint treatment of two or more members of the same family in order to change unhealthy patterns of communication and interaction.
Fetal alcohol effect (FAE) and Fetal alcohol syndrome (FAS).: The adverse and chronic effects of maternal alcohol abuse during pregnancy on her infant. FAS is the leading cause of mental retardation.
Figure-ground perception.: The ability to visually differentiate between a sensory stimulation and its background.
Forensic psychology.: The application of psychology to lawmaking, law enforcement, the examination of witnesses, and the treatment of the criminal; also known as legal psychology.
Forgetting curve.: The general, predictable pattern of the process of forgetting learned information.
Forh operations stage.: The fourth stage in Jean Piaget's theory of cognitive development characterized by a person's ability to reason about abstract concepts.
Fragile x syndrome.: A genetic disorder that causes mental retardation.
Free-recall learning.: The presentation of material to the learner with the subsequent task of recalling as much as possible about the material without any cues.
Frequency distribution.: Systematic representation of data, arranged so that the observed frequency of occurrence of data falling within certain ranges, classes, or categories is shown.
Frustration-aggression hypothesis.: Theory that aggression is a response to the frustration of some goal-directed behavior by an outside source.
Fugue.: A dissociative disorder in which a person has no recollection of events during an amnesic episode.
Functional disorder.: A psychological disorder for which no organic cause can be found.
Functionalism.: A psychological approach that focuses on how consciousness functions to help human beings adapt to their environment.

G

Gender identity disorder.: A condition in which an individual develops a gender identity inconsistent with his or her anatomical and genetic sex.
General adaptation syndrome.: A profound physiological reaction to severe stress.
Genital stage.: The fifth and last stage in Sigmund Freud's theory of psychosexual development in which a person's sexual drives are increased and parental attachments are dissolved.
Gestalt psychology.: A field of psychology that emphasizes the study of experience and behavior as wholes rather than independently functioning, disparate parts.
Group therapy.: The simultaneous treatment of several clients who meet regularly under the guidance of a therapist to receive support or to pursue personal change.

H

Hallucinations.: Perception of things or feelings that have no foundation in reality.
Hallucinogens.: Substances that cause hallucination when ingested.
Halo effect.: A type of bias in which one characteristic of a person or one factor in a situation affects the evaluation of the person's other traits.
Heuristics.: A methodical procedure for discovering solutions to problems.
Histrionic personality disorder.: A maladaptive or inflexible pattern of behavior characterized by emotional instability, excitability, over-reactivity, and self-dramatization.
Holtzman inkblot technique.: A projective test used to assess personality characteristics.
Human potential movement.: A movement that focuses on helping people achieve their full potential through an eclectic combination of therapeutic methods and discipline.
Humanistic psychology.: A theoretical and therapeutic approach that emphasizes people's uniqueness and their power to control their own destinies.
Hydrocephalus.: A condition in which fluid collects inside the skull.
Hypnosis.: A temporary narrowing of conscious awareness.
Hypochondria.: A disorder characterized by an excessive and habitual preoccupation with personal health and a tendency to interpret insignificant conditions as evidence of serious disease.
Hypothalamus.: A section of the forebrain that is involved in such aspects of behavior as motivation, emotion, eating, drinking, and sexuality.

I

Id.: In psychoanalytic theory, the most primitive, unconscious element of human personality.
Identification.: A type of defense mechanism in which a person takes on the characteristics of someone else.
Imprinting.: A type of learning characteristic of fowls that occurs only during a critical period of development soon after birth.
Impulse control disorders.: A psychological disorder characterized by the repeated inability to refrain from performing a particular action that is harmful either to oneself or others.
Independent variable.: The variable the experimenter manipulates in an experiment.
Inductive reasoning.: Way of thinking that uses comparison to reach conclusions.
Industrial psychology.: A subfield of applied psychology in which practical problems in the workplace are addressed through the application of psychological principles.
Information-processing theory.: An orientation that focuses on how people select, process, and internalize information and how they use it to make decisions and guide their behavior.
Instrumental behavior.: Behavior exhibited by persons in response to certain stimuli.
Intellectualization.: A type of defense mechanism in which a person detaches himself from a painful or anxiety-producing situation by dealing with it solely in intellectual, abstract terms and ignoring its emotional components.
Interest inventory.: A test that determines a person's preference for specific fields or activities.
Intermittent explosive disorder.: Uncontrollable episodes of aggression, where the person loses control and assaults others or destroys property.

J

Just noticeable difference.: Scientific calculation of the average detectable difference between two measurable qualities.

K

Kinesthetic sense.: The ability to know accurately the positions and movements of one's skeletal joints.
Kleptomania.: Overwhelming impulse to steal.
Kohlberg's theory.: A theory advanced by Lawrence Kohlberg on the six stages of moral development.
Kohs block test.: Intelligence test most often used with persons with language or hearing handicaps.

L

Language acquisition device.: Notion that some knowledge about language is built into the brain of the human child.
Latency stage.: The fourth stage in Sigmund Freud's theory of psychosexual development, in which a person's sexuality is dormant and his or her attentions are focused outside the family.
Law of effect.: Principle that states that behavior that leads to a satisfying outcome is likely to be repeated, while behaviors that lead to undesired outcomes are less likely to be repeated.
Learned helplessness.: An apathetic attitude stemming from the conviction that one's actions do not have the power to affect one's situation.
Learning theory.: Theory about how people learn and modify pre-existing thoughts and behavior.
Learning-to-learn.: The phenomenon of greater improvement in speed of learning as one's experience with learning increases.
Lobotomy.: The severing of the nerves connecting the frontal lobes of the brain and the thalamus or hypothalamus.
Locus of control.: A personality orientation characterized either by the belief that one can control events by one's own efforts or that the future is determined by forces outside one's control.
Longitudinal study.: Research method used to study changes over time.

M

Magnetic resonance imaging.: Technique for studying the brain using magnetic fields.
Mania.: Mood of elation without apparent cause or justification.
Maslow's hierarchy of needs.: Theory of human motivation developed by Abraham Maslow that emphasizes developing one's full potential. The hierarchy is depicted as a pyramid with five levels, ranging from the most basic needs at the bottom to the most complex and sophisticated at the top.
Mean.: The sum of the values of the points in a data set divided by the number of points.
Median.: The middle value in a group of measurements.
Melancholia.: Outdated term for depression itself and a clinically defined characteristic of major depression.
Menarche.: The first menstrual period, which occurs at an average age of 12.8 years for girls in the United States.
Meningitis.: Inflammation of the meninges, most often caused by infection.
Mental age.: A scale used to correlate intelligence to a child's chronological age.
Merrill-Palmer scales of mental development.: Tests that measure intelligence for children ages 18 months to four years of age.
Mesomorph.: A body type proposed by William Sheldon, who characterized mesomorphs as muscular and aggressive.
Metapsychology.: General term used to describe the attempt to establish principles to explain all psychological phenomena.
Methylphenidate.: The generic name for the drug Ritalin, the most commonly prescribed medication for treating attention deficit/hyperactivity disorder.
Midbrain.: Also called mesencephalon, the small area near the lower middle of the brain that controls smooth and reflexive movements and regulates attention, sleep, and arousal.
Milgram's obedience experiment.: A controversial experiment on conformity and obedience to authority conducted in the early 1960s by Stanley Milgram.
Minimal brain dysfunction.: Term used in connection with hyperactivity and/or attention deficit disorder.
Minnesota Multiphasic Personality Inventory.: Test used to gather information on personality, attitudes, and mental health.
Mnemonic strategies.: Any technique used for the purpose of memorizing or improving the function of memory in general.
Mode.: The most frequently occurring member of a set of numbers.
Montessori method.: A progressive system of education for early childhood through adolescence developed by Maria Montessori, emphasizing individualized, self-directed study.
Muscular dystrophy.: A category of inherited, incurable, and often life-threatening diseases in which the limb and trunk muscles deteriorate.

N

Narcissism.: Excessive preoccupation with self and lack of empathy for others.
Narcolepsy.: A sleep disorder whose primary symptoms is irresistible attacks of sleepiness during the daytime.
Negativism.: Tendency to resist complying with suggestions or directions.
Neocortex.: The exterior covering of the cerebral hemispheres of the brain.
Nervous system.: An electrochemical conducting network that transmits messages from the brain through the nerves to locations throughout the body.
Neuron.: Technical term for nerve cell, responsible for sending, receiving, and storing signals through a unique blend of electricity and chemistry.
Neurosis.: Term used to describe conditions involving anxiety or psychological distress.
Neurosurgery.: Surgery of the nervous system.
Neurotransmitter.: Chemical substances or molecules that aid in message transmission between neurons.
Nicotine.: Addictive substance in cigarettes.
Night terrors.: A childhood sleep disorder featuring behavior that appears to be intense fear.

O

Obsessive-compulsive disorder.: Mental illness characterized by the recurrence of intrusive, anxiety-producing thoughts accompanied by repeated attempts to suppress these thoughts through the performance of certain irrational, often ritualistic, behaviors.
Oedipus complex.: Theory set forth by Sigmund Freud that children are torn between feelings of love for one parent while feeling a sense of competition with the other.
Operant conditioning.: Approach to human learning based on the premise that human intelligence and will operate on the environment rather than merely respond to the environment's stimuli.
Opiates.: Addictive narcotic drug derived from opium.
Oppositional-defiant disorder.: A form of antisocial behavior disorder characterized by opposition to authority figures and by excessive anger and hostility.
Oral stage.: The first stage in Sigmund Freud's theory of psychosexual development in which a child is primarily concerned with gratification through sucking.
Organic disorder.: Disorder caused by a known pathological condition.

P

Paired-associate learning.: Pairing of two items (usually words) as stimulus and response.
Panic/panic disorders.: Acute feelings of intense fear, accentuated by increased heart rate, shortness of breath, sweating, and mild convulsions.
Paralysis agitans.: Another name for Parkinson's disease, a relatively common degenerative disorder of the central nervous system.
Paranoia.: A pervasive feeling of distrust of others.
Paraphilia.: Sexual feelings or behaviors that may involve sexual partners that are not human, not consenting, or that involve suffering by one or both partners. Common types of paraphilia are bestiality, exhibitionism, masochism, pedophilia, sadomasochism, and voyeurism.
Parapsychology.: The study of paranormal phenomena, the most significant being ESP and psychokinesis.
Parasomnia.: Sleeping disorder that involves unusual phenomena such as nightmares, sleep terrors, and sleepwalking that occur during sleep or during the period between sleeping and waking.
Passive-aggressive personality.: A pattern of behavior characterized by indirect resistance to the demands or expectations of others, usually by covert means.
Pedophilia.: Sexual activity with a child, generally under the age of 13.
Penis envy.: According to psychoanalytic theory, a girl's wish for a penis; she blames her mother for depriving her of a penis and desires her father because he possesses one.
Perception.: Area of psychology associated with the functioning of sensory systems and how information from the external world is interpreted.
Perfectionism.: Tendency to set unrealistically high standards for performance of oneself and others, along with the inability to accept mistakes or imperfections.
Pervasive development disorder.: A group of conditions involving serious impairment in several areas of development, including physical, behavioral, cognitive, social, and language development.

Phallic stage.: The third stage in Sigmund Freud's theory of psychosexual development in which a child experiences and resolves the Oedipal crisis and assumes his or her sexual identity.
Phenomenological therapy.: Also called humanistic therapy, an approach emphasizing a close, supportive relationship between the client and the therapist. Two well-known forms of phenomenological therapy are client-centered therapy and Gestalt therapy.
Phenylketonuria (PKU).: An inherited metabolic disease caused by a defect in the liver enzyme that prevents the conversion of the protein called phenylalanine into a useful form.
Phobia.: An intense, irrational, persistent fear that interferes with normal functioning.
Phonation disorders.: Disturbances in speech timbre, intensity, or pitch.
Placebo effect.: A scientifically significant response that cannot be explained by physiological variables and is assumed to be psychological in origin.
Positron emission tomography.: Technique for studying the chemistry and activity of the brain and to diagnose abnormalities such as tumors.
Post-traumatic stress disorder (PTSD).: A psychological disorder that develops in response to an extremely traumatic event that threatens a person's safety or life.
Preconscious.: According to Sigmund Freud, that part of the human mind that lies between the conscious and the unconscious, which can be accessed and brought into consciousness without the use of special techniques.
Preoperational stage.: The second stage in Jean Piaget's theory of cognitive development characterized by egocentrism, centration, and irreversibility in thought.
Primal therapy.: A type of treatment method where early traumas are re-experienced in physical ways.
Programmed learning.: A method of self-instruction that enlists machines or specially prepared books to teach information.
Projection.: A type of defense mechanism in which a person assigns to others characteristics or motivations that an individual would prefer not to recognize in himself.
Projective techniques.: Unstructured tests used in personality assessment that rely on the subject's interpretation of ambiguous stimuli.
Psychoactive drugs.: Category of drugs that affect mood and behavior.
Psychoanalysis.: A method of treatment developed by Sigmund Freud that emphasizes thorough examination of a person's unconscious motivations, feelings, and relationships.
Psychobiology.: Developed by Adolf Meyer, the integration of psychology and biology to treat the whole person.
Psychokinesis.: The ability to manipulate physical objects with the mind.
Psycholinguistics.: The psychology of language.
Psychophysics.: Subfield of psychology that studies the transformation from the physical to the psychological.
Psychosexual stages.: Stages of development described by Sigmund Freud that focuses on the location of sexual impulses at different ages.
Psychosis.: A symptom of mental illness characterized by a radical change in personality and a distorted or diminished sense of objective reality.
Psychosomatic disorders.: Physical illnesses that are believed to be psychologically based.
Psychostimulants.: Also called stimulants, drugs that produce increased levels of mental and physical energy and alertness and an elevated mood by stimulating the central nervous system.
Psychosurgery.: Medical procedure in which specific areas of the brain are destroyed or disabled through surgery as treatment for mental illness.
Psychotherapy.: The treatment of mental or emotional disorders through the use of psychological techniques rather than through physical or biological means.
Pyromania.: Irresistible urge to start fires.

R

Rating scale.: Any instrument designed to assist in the measurement of subjective evaluation.
Rational-emotive behavior therapy.: A mode of treatment developed by Albert Ellis in which a client is challenged to examine his or her irrational beliefs and taught to think more rationally with the goal of reducing emotional problems.
Rationalization.: A type of defense mechanism in which a person gives an intellectual reason or rationale for an emotionally motivated action in order to assign socially acceptable motives to one's behavior or to mask disappointment.

Reaction formation.: A type of defense mechanism in which a person deals with unacceptable feelings by adopting diametrically opposite ones.
Readiness test.: A test designed to assess the developmental condition of an individual to determine whether he or she would benefit from some particular experience.
Reflective listening.: A way of responding to a person in order to create empathy. Often used in a therapeutic setting, this technique involves accepting the person as he is and trying to understand the other person's reality.
Regression.: A type of defense mechanism in which a person reverts to behavior characteristic of an earlier period of life in order to gain access to the sources of gratification experienced during that period.
Reinforcement.: A stimulus that increases the probability that a particular behavior will occur.
Reliability (in testing).: Term used in testing to describe tests that produce consistent and reproducible results.
Repression.: A principal defense mechanism in which a person selectively forgets disturbing material.
Ribonucleic acid (RNA).: A complex organic substance involved in protein synthesis in cells.
Rorschach technique.: Popularly known as the "Inkblot Test," a widely used projective psychological test used to assess personality structure and identify emotional problems.
Rosenzweig picture frustration study.: A projective test consisting of 24 cartoon pictures, each portraying a frustrating situation, used to assess personality characteristics.

S

Sadomasochism.: Sexual behavior in which an individual achieves gratification either by experiencing pain or inflicting pain on another person.
Satanic ritualistic abuse.: Activities such as cannibalism, animal sacrifice, and child sexual abuse that are assumed to be carried out by organized underground cults.
Savant syndrome.: A condition in which a person has below normal intelligence combined with a special talent or ability in a specific area; also known as autistic savant or idiot savant.
Scapegoating.: A powerful and destructive phenomenon wherein a person or group of people are blamed for whatever is wrong.
Schemas.: A term defined by Jean Piaget as the basic units of knowledge that a person uses to organize past experiences and to understand new ones.
Schizophrenia.: A mental illness characterized by disordered thinking, delusions, hallucinations, emotional disturbance, and withdrawal from reality.
Scholastic Assessment Test.: Series of tests used to measure verbal and mathematical abilities and achievement in specific subject areas.
Seasonal affective disorder.: A bipolar disorder associated with lack of light and melatonin excess in the body. It generally corresponds to the seasons and how much light a person experiences.
Seizures.: A temporary series of uncontrollable muscle spasms brought on by unusual electrical activity in the brain.
Selective serotonin reuptake inhibitors (SSRIs).: A category of antidepressants, including Prozac, Zoloft, and Paxil.
Self-actualization.: The final and most complex step in Abraham Maslow's hierarchy of human motives, encompassing the basic need for self-fulfillment.
Self-conscious emotions.: Emotions such as guilt, pride, shame, and hubris.
Semantic memory.: The part of long-term memory dealing with words, their symbols, and meanings.
Sensitivity training.: A group experience that gives people new insight into how they relate to others.
Sensorimotor stage.: The first stage in Jean Piaget's theory of cognitive development characterized by a child's ability to grasp properties of objects and the concept of object constancy.
Sensory deprivation.: An experimental procedure involving prolonged reduction of sensory stimuli.
Serial learning.: Recalling patterns of facts or stimuli in the order in which they were presented.
Serial position function.: The predictable patterns of memory and forgetting when a person is presented with a list of stimuli.
Shaping.: A gradual behavior modification technique in which successive approximations to the desired behavior is rewarded.
Signal detection theory.: A psychological theory regarding a threshold of sensory detection.

Significance level.: A method to describe the reliability of test results.
Skinner box.: A specially made cage with levers for releasing food.
Sleep apnea.: Disrupted breathing that wakens a person repeatedly during the night.
Social cognitive theory.: Also known as social learning theory.
Social learning theory.: A theory that posits that people learn behavior by copying "models" and receiving reinforcements.
Social referencing.: The process by which infants seek out and interpret the emotional responses of their parents to form their own emotional understanding of unfamiliar events, objects, or persons.
Sociobiology.: A field of study combining biology and social sciences.
Somnambulism.: Also known as sleepwalking, a disorder that involves getting out of bed and moving about while still asleep.
Specific language impairment.: A condition of markedly delayed language development in the absence of any apparent handicapping conditions.
Split-brain technique.: Procedures used to study the activities of the two hemispheres of the brain separately, and independent of each other.
Stanford-Binet intelligence scales.: A widely used test to measure intelligence.
Stanford Progressive Matrices (SPM).: A test that assesses intelligence nonverbally in children and adults.
Strange situation.: A research technique developed by Mary Ainsworth and used in the assessment of attachments.
Stranger anxiety.: Fear of people with whom a child is not familiar.
Sublimations.: A type of defense mechanism in which unacceptable impulse is diverted to a more appropriate or socially acceptable form. It differs from displacement in that sublimations are generally associated with the conversion of impulses to scientific, artistic, and other creative or intellectual activities.
Superego.: In psychoanalytic theory, the part of the human personality that represents a person's inner values and morals; also known as conscience.
Sympathetic nervous system.: Part of the autonomic nervous system that mobilizes the body for action.
Synapse.: The tiny gap through which communication between two neurons takes place.

T

Tay-Sachs disease.: A genetically transmitted disease of the central nervous system affecting young children.
Temperament.: An individual's characteristic emotional nature, including energy level, prevailing mood, and sensitivity to stimuli.
Thalamus.: A collection of cell body clusters located in the middle of the forebrain that process sensory information.
Thematic apperception test.: A psychological test, in which subjects are shown a series of pictures and asked to make up a story, used to assess personality.
Tourette syndrome.: A genetic, neurological disorder characterized by motor and vocal tics and associated behavioral features including obsessions and compulsions and hyperactivity.
Traits.: A stable, relatively permanent characteristic.
Transference.: The tendency of clients to transfer to the therapist their emotional responses to significant people in their lives.
Transsexualism.: Condition in which a person defines him or herself as male or female in opposition to physical gender, sometimes seeking surgical procedures to change from one sex to the other.
Triangulation.: A situation in which two persons deal with the tension between them by using a third person as a buffer.
Trichotillomania.: Uncontrollable or overwhelming urge to pull out one's own hair.
Type A personality.: A personality characterized by competitive achievement, time urgency, and aggressiveness or hostility when frustrated.

U

Unconditioned response.: Response that is natural and not learned, such as jerking the hand from a hot stove.
Unconditioned stimulus.: Stimulus that naturally elicits behavior, such as food.
Unconscious.: The part of the mind whose contents people resist bringing into awareness.

V

Validity (in testing).: Term used in testing to describe tests that measure what they are intended to measure.
Vocational aptitude test.: A predictive test designed to measure an individual's potential for success and satisfaction in any of various occupations and professions.
Voyeurism.: A sexual disorder in which a person finds sexual excitement in watching unsuspecting people who are nude, undressing, or having sex.

W

Wechsler intelligence scales.: Series of intelligence tests encompassing both verbal and nonverbal abilities.
Wernicke's aphasia.: A type of aphasia in which a person's speech is overflowing with words that do not convey meaning.