Glossary

"The noblest pleasure is the joy of understanding."

~ Leonardo da Vinci

A

Absolute threshold - The minimum amount of stimulation necessary for someone to detect a stimulus half of the time.
Accommodation - (1) Adjustment of the lens’s thickness by specialized muscles in order to change the degree to which it bends light. (2) In Piaget’s theory, the process of revising existing schemas to incorporate information from a new experience.
Acetylcholine - A major neurotransmitter class that can behave as both an inhibitory and an excitatory signal, supporting heart and skeletal muscle, and cognitive function.
Achievement gaps - Persistent differences in the performance of certain groups of people, usually based on characteristics like race or gender.
Achievement test - A test that is designed to measure how much a person has learned over a certain period of time.
Acquisition - The initial learning of an association between the unconditioned and conditioned stimuli during classical conditioning.
Action potential - A rapid change in voltage created by a neuron when it is sufﬁciently stimulated to surpass a critical threshold; serves as the basis for neural signaling.
Activation-synthesis hypothesis - The hypothesis that dreams result from the brain’s attempt to organize the chaotic patterns of brain activity during sleep into a semi-coherent narrative.
Acute stress disorder - A trauma- or stressor-related disorder than lasts less than one month.
Adaptation - A phenomenon whereby an individual stops noticing a stimulus that remains constant over time, resulting in enhanced detection of stimulus changes.
Adolescence - The period of transition between childhood and adulthood.
Adrenal glands - The endocrine glands located on top of the kidneys; they produce a variety of hormones, including adrenaline and cortisol, that are central to the stress response.
Adult plasticity - The shaping and reshaping of neural circuits throughout adulthood.
Affect heuristic - A mental shortcut for making judgments and decisions that involves relying on affect: the good-for- me or bad-for-me feelings we associate with various objects and events in the world.
Affect-as-information perspective - The idea that affective states play an important role in shaping problem-solving and decision making.
Affective conditioning - A form of conditioning in which a previously neutral stimulus acquires positive or negative value.
Affective forecasting errors - People’s inability to accurately predict the emotional reactions they will have to events.
Agonist - A chemical that mimics the action of a neurotransmitter.
Agoraphobia - A fear of being in situations in which help might not be available or escape might be difﬁcult or embarrassing.
Alcohol myopia - A phenomenon whereby alcohol intoxication leads to a narrowing of attention and impairment of the ability to exert top-down control over impulses.
Alexithymia - An extreme difﬁculty in identifying and labeling one’s emotions.
Algorithm - A step-by-step procedure for solving problems that guarantees a solution.
Allele - A variant form of a gene; humans have two alleles per gene, one inherited from each parent.
Allostatic load - The sustained activation of many physiological systems in response to frequent or chronic stressors.
Alpha waves - Low-frequency, high-amplitude electrical waves in the brain (as measured by EEG) that occur in a rhythmic pattern and are associated with being awake yet relaxed with the eyes closed.
Alzheimer’s disease - A degenerative brain disorder characterized by the progressive and widespread loss of nerve cells, leading to memory problems, disorientation, and eventually total helplessness.
Amino acids - The brain’s most abundant class of neurotransmitters, including glutamate (important for neuronal excitation) and gamma-aminobutyric acid (GABA, important for neuronal inhibition and the regulation of muscle tone).
Amnesia - The loss of memory due to brain damage or trauma.
Amplitude - The height of the crests of a wave.
Amygdala - A component of the limbic system important for registering the emotional signiﬁcance of events.
Anhedonia - Diminished interest or pleasure in nearly all of the activities that usually provide pleasure, such as eating, exercising, or spending time with friends.
Anorexia nervosa - An eating disorder characterized by an extreme concern with being overweight and by compulsive dieting, sometimes to the point of self-starvation. See also bulimia nervosa.
Antagonist - A chemical that competes with a naturally occurring neurotransmitter to block neurotransmission.
Anterograde amnesia - The inability to transfer information from short-term to long-term memory, preventing new long-term memories from forming.
Antidepressant - A medication intended to treat the symptoms of depression.
Antisocial personality disorder - A personality disorder marked by a pervasive pattern of disregard for and violation of the rights of others, as well as a lack of empathy and remorse.
Anxiety - A feeling of intense worry, nervousness, or unease.
Anxiolytic - A type of drug that alleviates the symptoms of anxiety; also called a tranquilizer.
Aptitude test - A test designed to measure a person’s potential to learn new skills.
Assessment - The process of developing and validating tools to accurately measure and quantify traits and other features of personality.
Assimilation - In Piaget’s theory, the process of using an existing schema to interpret a new experience.
Association cortex - The cortex that integrates information coming in from the senses with existing knowledge.
Associative learning - A form of learning that involves making connections between stimuli and behavioral responses.
Attachment - The strong, enduring, emotional bond between an infant and a caregiver.
Attention-deficit/hyperactivity disorder (ADHD) - A disorder usually diagnosed in young children that involves a wide range of symptoms, including blurting out answers in class, ﬁdgeting, and difﬁculty in shifting attentional focus.
Attitude - An orientation toward some target stimulus that is composed of an affective feeling, a cognitive belief, and a behavioral motivation toward the target.
Attribution - Assignment of a causal explanation for an event, action, or outcome.
Atypical antidepressant - A medication that works in various ways on serotonin, norepinephrine, and dopamine systems to combat the symptoms of depression.
Atypical antipsychotics - Newer antipsychotic medications that block the neurotransmission of dopamine but have enhanced beneﬁts in terms of limiting or eliminating negative symptoms.
Autism spectrum disorder - A disorder usually diagnosed in young children, and characterized by a wide range of developmental problems, including persistent deﬁcits in social communication/interaction and restricted or repetitive patterns of interest or behavior.
Automaticity - The ability to perform a task without conscious awareness or attention.
Autonomic nervous system (ANS) - The system that allows us to feel internal sensations from and controls automatic movements of the organs, such as heartbeat.
Availability heuristic - A mental shortcut for deciding how frequent or probable something is based on how easily examples come to mind.
Aversive racism - A tendency, even among egalitarian- minded people, to have unconscious negative reactions to people of racial or ethnic outgroups.
Axon - The part of the neuron that transports electrical impulses to other neurons via the terminal branches.

B

Babbling - The production of speech sounds by infants, usually beginning around 6 or 7 months of age.
Basal ganglia - A group of interconnected structures that are an evolutionarily older subcortical motor system necessary for planning and executing movement.
Basilar membrane - A structure in the cochlea where the auditory cilia, or auditory sensory neurons, are located.
Behavioral approaches - A family of therapeutic approaches based on the idea that problematic behaviors are the result of learning.
Behavioral genetics - An approach that estimates the heritability of a trait by statistically comparing patterns of similarity in the behavioral or personality proﬁles of people who differ in their genetic relatedness.
Belief perseverance - The tendency for people to resist changing their beliefs, even when faced with disconﬁrming evidence.
Benzodiazepine - A common type of drug (such as Xanax, Klonopin, and Ativan) used to treat anxiety disorders.
Beta blocker - A medication that controls autonomic arousal and thereby decreases the negative spiral that occurs when an anxious person feels even more anxious when sensing a bodily response to an anxiety-producing situation.
Beta waves - High-frequency, low-amplitude electrical waves in the brain (as measured by EEG) that occur in a rhythmic pattern and are associated with being awake and actively thinking.
Binge-eating disorder - An eating disorder characterized by repeated episodes of binge eating without inappropriate compensatory behavior.
Binocular cues - Depth information gathered from the separation between an individual’s two eyes.
Binocular disparity - The magnitude of difference between the images projected on an individual’s two eyes.
Biological–neuroscience perspective - The psychological perspective that seeks to understand the biological underpinnings of how humans think, act, and behave.
Biopsychosocial model - A way of understanding what makes people healthy by recognizing that biology, psychology, and social context all combine to shape health outcomes.
Bipolar disorder - A mood-related disorder characterized by both manic (excited and energetic) episodes and depressive episodes, with normal periods interspersed; formerly called manic-depressive illness.
Blind spot - An area in the middle of the visual ﬁeld where there are no photoreceptors and no information can be received.
Blocking - A classical conditioning phenomenon whereby a prior association with a conditioned stimulus prevents learning of an association with another stimulus because the second one adds no further predictive value.
Body Mass Index (BMI) - A measure of whether someone is at a healthy weight or not; BMI is calculated as one’s weight in kilograms divided by the square of one’s height in meters.
Body weight set point - The weight an organism will seek to maintain despite alterations in dietary intake.
Bounded rationality - The idea that rational decision making is constrained by limitations in people’s cognitive abilities, available information, and time.
Brain networks - The collections of brain regions that are connected and work together to support brain functions.
Brainstem - The lowest region of the brain; it sits on top of and is continuous with the spinal cord, collecting sensory signals from the body and sending signals down from the brain to create movement and regulate vital functions.
Broaden-and-build function - The idea that positive emotions evolved as a signal of safety, allowing for exploration and creativity.
Bulimia nervosa - An eating disorder characterized by repeated binge-and-purge bouts. See also anorexia nervosa.
Bystander effect - The lower likelihood of people coming to the aid of a victim when in the presence of other observers than if they are alone.

C

Cannon–Bard theory - The theory that a stimulus elicits an emotion by triggering a particular response in the brain (in the thalamus), which then causes both the physiological changes associated with the emotion and the emotional experience itself.
Case study - An observational research method in which researchers study one or two individuals in-depth, often those who have a unique condition.
Cell body - The part of the neuron that collects neural impulses, contains the nucleus, and provides life-sustaining functions for the cell; also called the soma.
Central nervous system (CNS) - The system composed of the brain and spinal cord; information from your body travels to the brain by way of the nerves of your spinal cord.
Cerebellum - A hindbrain structure that supports a variety of functions, including coordination, precision, balance, and accurate timing.
Cerebral cortex - The outermost layer of the brain; supports cognitive skills, complex emotions, and complex mental activity, including your sense of mind and self.
Challenge reactivity - A cardiovascular pattern of responding to a situation whereby the heart pumps out more blood and the vasculature dilates, allowing efﬁcient circulation through the body.
Change blindness - A form of inattentional blindness, in which a person fails to notice changes in a visual stimulus.
Childhood - The period of life spanning the end of infancy (about age 2) and the start of adolescence.
Chunking - The process of grouping stimuli together in chunks in working memory to increase the amount of information stored in short-term memory.
Circadian rhythm - A regular, 24-hour pattern of bodily arousal. Also known as the biological rhythm or biological clock.
Civil commitment laws - Laws that specify when people can be hospitalized (“committed”) against their will for mental treatment.
Classical conditioning - A passive form of learning by which an association is made between a reﬂex-eliciting stimulus (e.g., A shock) and other stimuli (e.g., A sound).
Client-centered therapy - A form of humanistic therapy, pioneered by Carl Rogers, in which the therapist’s genuineness, unconditional positive regard, and empathic understanding are crucial to therapeutic success; also known as person-centered therapy, client-centered therapy seeks to help clients accept themselves as they are without pretense or self-imposed limits.
Clinical assessment - A procedure for gathering the information that is needed to evaluate an individual’s psychological functioning and to determine whether a clinical diagnosis is warranted.
Clinical interview - An interview in which a clinician asks the patient to describe his or her problems and concerns.
Clinical perspective - The psychological perspective that focuses on the causes and treatment of psychological disorders, with the goal of improving human well-being, daily functioning, and social relationships.
Cochlea - A spiral structure in the inner ear where the basilar membrane, containing auditory sensory neurons, is located.
Cognition - All of the mental activities associated with thinking, including knowing, remembering, solving problems, making judgments and decisions, and communicating.
Cognitive approaches - A family of therapeutic approaches based on the idea that maladaptive behaviors arise due to errors in thinking.
Cognitive development - Changes in all of the mental activities associated with thinking, knowing, remembering, and communicating.
Cognitive dissonance - A sense of conﬂict between people’s attitudes and actions that motivates efforts to restore cognitive consistency.
Cognitive perspective - The psychological perspective that studies the mental processes that underlie perception, thought, learning, memory, language, and creativity.
Cognitive psychology - The scientiﬁc study of mental activities and how they operate.
Cognitive restructuring - A set of cognitive therapy techniques for changing a person’s maladaptive beliefs or interpretations through persuasion and confrontation.
Cognitive therapy - An approach to therapy that tries to change patients’ habitual modes of thinking about themselves, their situation, and their future.
Cognitive unconscious - The various mental processes that support everyday functioning without conscious awareness or control.
Cognitive-behavioral therapy - A hybrid form of psychotherapy focused on changing the patient’s habitual interpretations of the world and ways of behaving; it combines cognitive and behavioral approaches to therapy.
Color constancy - The phenomenon whereby the brain adjusts its perception of color to hold it constant, taking into account changes in lighting conditions.
Common factor - A factor related to therapy outcome that is common to many different types of treatment (e.g., Therapeutic alliance).
Comorbidity - The occurrence of two or more disorders in a single individual at a given point in time.
Compulsion - A ritualistic action performed to control an obsession.
Concept - A mental category that groups similar objects, events, ideas, or people.
Concordance rate - The probability that a person with a particular familial relationship to a patient (for example, an identical twin) has the same disorder as the patient.
Concrete operational period - In Piaget’s theory, the period of development from age 7 to 12, during which a child becomes capable of transforming and interrelating schemas to solve complex problems, but is able to apply this thinking only to concrete objects or events.
Conditioned response (CR) - A response that occurs in the presence of the conditioned stimulus after an association between the conditioned and unconditioned stimulus is learned.
Conditioned stimulus (CS) - A stimulus that has no prior positive or negative association but comes to elicit a response after being associated with the unconditioned stimulus.
Conditioned taste aversion - A classically conditioned response where individuals are more likely to associate nausea with food than with other environmental stimuli.
Cones - Photoreceptor cells that are responsible for high- resolution color vision.
Confirmation bias - The tendency to look for and weigh evidence that conﬁrms preexisting beliefs more strongly than evidence that is inconsistent with those beliefs.
Conformity - The process by which people implicitly mimic, adopt, or internalize the behaviors and preferences of those around them.
Confound - An alternative explanation for a relationship between two variables; speciﬁcally, in an experiment, when two experimental groups accidentally differ on more than just the independent variable, which causes a problem for internal validity.
Consciousness - The moment-by-moment awareness of the external environment as well as one’s own thoughts, feelings, and behaviors.
Conservation - The idea that the physical properties of an object, such as mass, volume, and number, remain constant despite superﬁcial changes in the object’s shape or form.
Consolidation - The process whereby memory storage is integrated and becomes stable in the brain.
Construct validity - The speciﬁc assessment of how accurately the operationalizations used in a study capture the variables of interest.
Contact hypothesis - The proposal that prejudice can be reduced through sanctioned, friendly, and cooperative interactions between members of different groups working together as equals toward a common goal.
Contingency management - A behavioral therapy in which certain behaviors are reliably followed by well-deﬁned consequences.
Continuous reinforcement schedule - A reinforcement schedule in which a behavior is rewarded every time it is performed.
Contralateral - The opposite-side organization of the brain, whereby one side of the body is connected to and controlled by the opposite brain hemisphere.
Control group - In an experiment, a group or condition in which some proposed cause is not present.
Conventional stage - In Kohlberg’s theory, a period in moral development in which people make moral judgments based on caring for others and upholding social roles and rules.
Corpus callosum - The bridge of ﬁbers that connects the two halves of the brain.
Correlational research - A type of study that measures two (or more) variables in the same sample of people, and then observes the relationship between them.
Cortisol - A hormone produced by the adrenal cortex that is often elevated in response to stressful events.
Criminal commitment - Enforced hospitalization (“commitment”) for criminals who plead not guilty by reason of insanity.
Critical periods - The periods early in life during which very speciﬁc experiences must occur to ensure the normal development of a characteristic or behavior.
Critical thinking - The purposeful, reasoned, and goal- directed process of exploring a situation or problem; it is an essential component of psychological literacy.
Cross-sectional design - A methodological approach to studying development that compares participants of different age groups to one another.
Crystallized intelligence - A component of general intelligence that involves accumulated knowledge and skills.
Cued recall - A form of retrieval that is facilitated by providing information related to the stored memory.
Cultural competence - An understanding of how clients’ cultural backgrounds shape their beliefs, values, and expectations for therapy.
Cultural perspective - The psychological perspective that seeks to understand how cultural context affects people’s thoughts and preferences.
Cultural transmission - The transfer of information from one generation to another that is maintained not by genetics, but by teaching and learning.
Culturally appropriate therapy - Therapy that is conducted in a manner that is sensitive to the client’s cultural background and expectations.
Culture - The rules, values, customs, and beliefs that exist within a group of people who share a common language and environment; culture passes from generation to generation as children learn it from their parents, caregivers, and the larger society.
Cybertherapy - A nontraditional form of therapy in which the therapy is conducted over the internet.
Cytokines - Molecules, released as part of the body’s natural immune response, that respond to injury or infection by causing fever and inﬂammation.

D

Damage plasticity - The neural modiﬁcation following injury that largely takes the form of brain reorganization.
Data - A set of empirical observations that scientists have gathered.
Deep brain stimulation (DBS) - The insertion of an electrode deep in a patient’s brain to alter the activity of speciﬁc brain regions (e.g., To treat depression or obsessive-compulsive disorder).
Deep encoding - Encoding based on an event’s meaning as well as connections between the new event and past experience.
Default mode network - An interconnected system of brain regions that are active when the mind is alert and aware but not focused on any particular task, such as during mind wandering.
Defense mechanisms - The various ways in which the ego is thought to cope with conﬂict between the unconscious desires of the id and the moral constraints of society.
Deinstitutionalization - A movement that began in the 1950s that aimed to provide better, less expensive care for chronically mentally ill individuals in their own communities rather than at large, centralized hospitals.
Delta waves - Very-low-frequency, high-amplitude electrical waves in the brain (as measured by EEG) that occur in a rhythmic pattern and are associated with deep, Stage 3 sleep.
Delusions - False beliefs that are rigidly maintained despite overwhelming contradictory evidence.
Dendrites - The part of the neuron that receives chemical messages from other neurons.
Denial - A defense mechanism in which the ego prevents the perception of a painful or threatening reality as it is occurring.
Dependent variable - The measured variable in an experiment.
Depolarization - Occurs when a neuron’s voltage becomes more positive; the ﬁrst phase of the action potential.
Depressants - Drugs that decrease activity levels in the nervous system.
Depression - A mood disorder characterized by feelings of sadness, emptiness, and anhedonia (diminished interest or pleasure in activities that usually provide pleasure, such as eating or exercising).
Depressive realism - The painful awareness of personal limitations that render outcomes uncontrollable, in contrast to a more commonly held illusion of control for those who are not depressed.
Descriptive research - A type of study in which researchers measure one variable at a time.
Descriptive statistics - Graphs or computations that describe the characteristics of a batch of scores, such as its distribution, central tendency, or variability.
Developmental perspective - The psychological perspective that studies how people change physically, cognitively, socially, and emotionally as they age.
Developmental psychology - The scientiﬁc study of how people change physically, cognitively, socially, and emotionally from infancy through old age.
Dialectical behavior therapy (DBT) - An eclectic therapy for treating borderline personality disorder, pioneered by Marsha Linehan, that includes elements of cognitive, behavioral, humanistic, and psychodynamic therapies.
Diathesis-stress model - A conception of psychopathology that distinguishes the factors that create a risk of illness (the diathesis) from the factors that turn the risk into a problem (the stress).
Difference threshold - The minimum difference required between two stimuli for an observer to detect a difference half the time.
Differential sensitivities hypothesis - The idea that some people have a genetic predisposition to be more strongly affected by variation in their environment, especially during early childhood.
Diffusion chain - A process in which individuals learn a behavior by observing a model and then serve as models from whom other individuals can learn.
Diffusion of responsibility - A tendency for people in a group to assume that someone else is in a better position to act or has already acted.
Dimensional approach - An approach to analyzing emotions that focuses on dimensions such as pleasantness and activation. See also discrete emotions approach.
Discrete emotions approach - An approach to analyzing emotions that focuses on speciﬁc emotions such as anger, fear, and pride. See also dimensional approach.
Discrimination - (1) A tendency for individuals to receive different treatment or outcomes as a result of their membership in a given social group. (2) Learning to respond to a particular stimulus but not to similar stimuli, thus preventing overgeneralizations.
Dishabituation - The recovery of a response that has undergone habituation, typically as a result of the presentation of a novel stimulus.
Displacement - A defense mechanism in which the ego redirects the aggressive impulses of the id from their intended targets to more defenseless targets.
Display rules - Cultural rules that govern the expression of emotion.
Dissociation - (1) The neuropsychological evidence, following brain damage or a lesion, that a speciﬁc brain area is involved in a particular function but not in others. (2) A splitting of conscious awareness. In the case of hypnosis, one stream of awareness stays connected to the hypnotist’s suggestions whereas another stream observes the person’s experiences in a disconnected way.
Dissociative identity disorder (DID) - A disorder (formerly known as multiple personality disorder) deﬁned by the presence of two or more distinct personality states within a single person, each with its own style, habits, beliefs, and memories.
Dizygotic - Twins who share 50 percent of their genetic material because they developed from two separate fertilized eggs.
Dodo bird verdict - An expression used to summarize the comparative effectiveness of different forms of psychotherapy. According to the dodo bird in Alice in Wonderland, “Everybody has won, and all must have prizes.” With regard to psychotherapy, the dodo bird verdict means that all the major forms of psychotherapy are equally effective.
Dopamine hypothesis - The hypothesis that schizophrenia arises from an abnormally high level of activity in brain circuits that are sensitive to the neurotransmitter dopamine.
Double-blind study - A study in which participants are assigned to experimental conditions while keeping both the participants and the researchers unaware of who is assigned to which group.
Down syndrome - A developmental disorder caused by an extra copy of chromosome 21. It is characterized by intellectual disabilities, delays in motor development, and increased risk for a range of health problems.
Dreams - Sequences of images, emotions, and thoughts, sometimes vivid and story-like, that are experienced during sleep.
Drive - A state of internal bodily tension, such as hunger or thirst or the need for sleep.
Drug addiction - An uncontrollable compulsion to use a substance even though that substance damages the user’s health and everyday functioning.
Drug tolerance - The diminished response to a drug that results from prolonged use, leading the drug user to require larger doses to achieve the same original effect.
Dual-processing theory - The proposal that people have two types of thinking that they can use to make judgments and decisions: one that is slower, more effortful, and leads to more thoughtful and rational outcomes, and one that is fast, fairly effortless, and leads to decent outcomes most of them time.

E

Echoic memory - A rapidly decaying store of auditory sensory information.
Eclecticism - An approach to treatment that deliberately weaves together multiple types of therapy.
Effect size - A numerical estimate of the strength of the relationship between two variables. It can take the form of a correlation coefﬁcient or, for an experiment, the difference between two group means divided by the standard deviations of the two groups.
Ego - The component of personality in Freud’s psychoanalytic theory that represents the largely conscious awareness of reality and the ability to mediate the needs of the id within the constraints of reality.
Ego depletion - A state of diminished self-regulatory ability due to repeated demands on cognitive resources required for self-regulation. See also strength model of ego control.
Ego psychology - A school of psychodynamic thought that emphasizes the skills and adaptive capacities of the ego.
Egocentrism - In Piaget’s theory, the difﬁculty that preoperational children have with thinking about how objects or situations are perceived by other people.
Elaboration likelihood model (ELM) - A theory of persuasion contending that attitudes can change by two different routes: a central route that focuses on the strength of the argument and a peripheral route that is sensitive to more superﬁcial cues.
Electroconvulsive therapy (ECT) - A biological treatment, mostly used for cases of severe depression, in which a brief electric current is passed through the brain to produce a convulsive seizure.
Electroencephalography (EEG) - The recording of electrical waves from many thousands of neurons in the brain, gathered using electrodes placed on the scalp.
Embryo - An unborn, developing offspring, identiﬁed in humans between the 2nd and 8th week of pregnancy.
Emerging adulthood - The period between adolescence and adulthood, roughly the ages of 18 to 25, when people take time to ﬁnish schooling, gain ﬁnancial independence from their parents, and establish careers and families.
Emotion - The coordinated behaviors, feelings, and physiological changes that occur when a situation becomes relevant to our personal goals.
Emotion regulation - An attempt to modify one or more aspects of the emotion-response trajectory.
Emotional perspective - The psychological perspective that seeks to understand how the human capacity to feel, express, and perceive emotions plays an important role in decision making, behavior, and social relationships.
Empathy - The capacity to accurately track what others are feeling.
Empathy gap - The inability to accurately simulate the mental suffering of another person.
Empirical - Based on astute observation and accurate measurement.
Empirically supported treatment (EST) - A clinical method that research has shown to be effective for treating a given disorder.
Encoding - The process of taking information from the world, including our internal thoughts and feelings, and converting it to memories.
Encoding specificity principle - The idea that retrieval is best when the present context recreates the context in which information was initially encoded.
Endocrine system - A network of glands that produces and releases hormones into the bloodstream to regulate the body’s activities.
Epigenetics - The study of how life events can change how genes are expressed.
Episodic memory - The explicit recollection of personal experience that requires piecing together the elements of that time and place.
Epithelium - A mucous membrane in the nasal cavity that contains the olfactory receptor neurons.
Estrus - A female mammal’s period of sexual receptivity.
Evidence - The available body of facts or information indicating whether a belief or proposition is true or valid.
Evolutionary perspective - The psychological perspective on behavior that seeks to identify how humans’ evolutionary past shapes certain cultural universals that all human beings share, such as the preference for fairness.
Executive functions - The cognitive processes that allow us to plan, focus attention, and organize multiple tasks to complete our goals; associated with the function of the prefrontal cortex.
Experiential therapies - The collective term for modern humanistic therapies.
Experimental group - In an experiment, a group or condition in which some proposed cause is present.
Experimental research - A study in which one variable is manipulated, and the other is measured. Experimental research can provide evidence that one variable causes another.
Explanatory style - How a person explains why bad things happen to him or her.
Explicit attitude - The consciously reported evaluation a person has in response to a target stimulus.
Explicit memory - A form of memory that involves intentional and conscious remembering.
Exposure techniques - Behavioral techniques designed to remove the anxiety connected to a feared stimulus through repeated approach toward the feared stimulus.
External validity - The degree to which it is reasonable to generalize from a study’s sample to its population of interest.
Extinction - An active learning process in which there is a weakening of the conditioned response to the conditioned stimulus in the absence of the unconditioned stimulus.
Extrinsically rewarding - Being pursued because of rewards that are not an inherent part of the activity or object. See also intrinsically rewarding.

F

Factor analysis - A statistical technique that groups a large set of variables into a smaller set of constructs based on how they correlate with one another.
False consensus - The tendency to overestimate the extent to which other people’s beliefs and attitudes are similar to our own.
False positive - A statistically signiﬁcant ﬁnding that does not reﬂect a real effect.
Feature detectors - Specialized cells in the visual cortex that respond to basic features such as lines, edges, and angles.
Fetal alcohol syndrome - A developmental disorder that affects children exposed to alcohol during prenatal development. Its effects include a range of learning and behavioral challenges and differences in physical size and facial characteristics.
Fetus - An unborn, developing offspring, identiﬁed in humans between the ninth week of pregnancy and birth.
Five-factor model - The dominant model in the trait approach to personality, which posits ﬁve key dimensions along which humans vary: open-mindedness to experience, conscientiousness, extraversion, agreeableness, and neuroticism.
Fixed-interval schedule - A reinforcement schedule based on a ﬁxed amount of time before a reward is given.
Fixed-ratio schedule - A reinforcement schedule in which a speciﬁc number of behaviors are required before a reward is given.
Flashbulb memories - A vivid memory for an emotionally signiﬁcant event, thought to be permanent and detailed, as if frozen in time like a photograph.
Flat affect - Diminished or absent facial expressions of emotion.
Flow - A subjective experience of having one’s attention so focused on an activity or task that any sense of self- awareness disappears.
Fluid intelligence - A component of general intelligence that involves the ability to deal with new and unusual problems.
Forgetting curve - The retention of information over various delay times.
Fovea - A small pit in the center of the retina that is densely packed with cones.
Framing - The particular way that an issue, decision, or set of options is described. Framing can change decisions by shifting the decision maker’s reference point.
Free association - A method used in psychoanalytic therapy in which the patient says anything that comes to mind, no matter how apparently trivial, embarrassing, or disagreeable.
Free recall - Accessing information from memory without any cues to aid your retrieval.
Frequency - The number of cycles per second of a wave.
Frequency distribution - A descriptive statistic that takes the form of a bar graph in which the possible scores on a variable are listed on the x-axis and the total number of people who had each score is plotted on the y-axis.
Frequency theory - A theory of pitch perception stating that the brain uses the frequency of auditory sensory neuron ﬁring to indicate pitch.
Frontal lobe - A lobe located in the front of the head; contains the primary motor cortex and a map of the body’s muscles, essential for movement and planning.
Functional fixedness - An obstacle to problem solving that involves focusing on an object’s typical functions, thus failing to recognize atypical functions that could help solve a problem.
Functional magnetic resonance imaging (fMRI) - A variation of MRI that measures brain function by tracking oxygen in the blood ﬂow through the brain.
Fundamental attribution error - The tendency to assume that people’s actions are more the result of their internal dispositions than of the situational context.

G

Gender schema - A mental representation for the concept of gender that includes assumptions about how people with different genders are supposed to think, feel, and act.
Gender socialization - The process by which people internalize social expectations and attitudes associated with their perceived gender.
Gene × Environment interactions - The interaction between environmental factors and a person’s genetic predispositions that determine the unique phenotypes expressed in personality.
Gene expression - The turning on and off of genes in a particular cell to determine how that cell functions.
General adaptation syndrome - A broad-based physiological response to a physical threat that unfolds in three stages: alarm, resistance, and exhaustion.
General aggression model - An integrative framework of the various factors and psychological processes that contribute to an act of aggression.
General intelligence (g factor) - A general mental ability that Charles Spearman hypothesized is required for virtually any mental test.
Generalization - The tendency to respond to stimuli that are similar to the conditioned stimulus, so that learning is not tied too narrowly to a speciﬁc stimulus.
Generalized anxiety disorder (GAD) - An anxiety disorder characterized by continuous, pervasive, and difﬁcult-to- control anxiety.
Genes - The basic physical and functional units of heredity; made up of DNA.
Genotype - The genetic makeup of an organism composed of the organism’s complete set of genes.
Gestalt psychology - A school of psychological thought that attempted to explain how various elements group together to form objects, arguing that perception is more than a simple piecing together of building blocks.
Gestalt therapy - A form of humanistic therapy, pioneered by Fritz Perls, that aims to help patients integrate inconsistent aspects of themselves into a coherent whole by increasing self-awareness and self-acceptance.
Glia - The cells that make up the myelin sheath around neurons to insulate, support, and nourish neurons and modulate neuronal function.
Global workspace hypothesis - The hypothesis that conscious awareness arises from synchronized activity, from across various brain regions, that is integrated into coherent representations of an experience.
Glomeruli - A spherical cluster of neurons in the olfactory bulb.
Glucostatic hypothesis - The hypothesis that hunger and eating are regulated by the body’s monitoring and adjustment of blood glucose levels.
Grammar - A system of rules that governs the way that language parts are put together so that people can understand each other.
Group polarization - A tendency for people’s attitudes to become more extreme after they discuss an issue with like- minded others.
Group therapy - A form of therapy in which two or more patients meet with one or more therapists at a time.
Groupthink - A form of biased group decision making whereby pressure to achieve consensus leads members of the group to avoid voicing unpopular suggestions.
Growth mindset - The belief that human personality and behavior can be changed.
Gustation - The sense of taste.

H

Habituation - A form of non-associative learning by which an organism becomes less responsive to a repeated stimulus.
Habituation - A simple form of learning that involves a decreased response to repeated stimulation.
Hallucinations - Sensory experiences that occur in the absence of any sensory input or stimulation.
Happiness set point - The level of happiness that is characteristic of a given individual.
HARKing - A questionable research practice known as “Hypothesizing After the Results are Known,” in which researchers create an after-the-fact hypothesis about an unexpected research result, making it appear as if they predicted it all along.
Health psychology - An interdisciplinary ﬁeld that investigates the links among behavior, cognition, and physical health.
Heritability - An indication of how much variation in phenotype across people is due to differences in genotype.
Heuristic - A mental shortcut that allows people to efﬁciently solve problems and make judgments and decisions.
Hierarchy of motives - The order in which needs are thought to become dominant. According to Abraham Maslow, people will strive to meet their higher-order needs, such as self- actualization and self-transcendence, only when their lower, more basic needs like food and safety have been met.
Hindsight bias - The tendency, once some outcome is known, to overestimate the likelihood that one would have predicted that outcome in advance.
Hippocampus - A component of the limbic system crucial for certain aspects of memory, the ability to navigate the environment, and the ability to think about the future.
Homeostasis - The body’s tendency to maintain internal equilibrium through various forms of self-regulation.
Horizontal transmission - The transmission of skills between peers.
Hormones - The blood-borne chemicals that travel through the circulatory system enabling the brain to regulate the body’s activities.
Humanistic approach - An approach to therapy centered around the idea that people must take responsibility for their lives and actions.
Hypnosis - A relaxed state of mind in which a person is especially receptive to suggestions made by a hypnotist and feels their actions and thoughts are happening to them rather than being produced voluntarily.
Hypnotic analgesia - A reduction in pain perception caused by a hypnotic suggestion.
Hypomania - A mild form of mania marked by high spirits, happiness, self-conﬁdence, and a high level of nervous energy.
Hypothalamic-Pituitary-Adrenal (HPA) axis - A physiological system that governs the body’s prolonged response to a stressful event, enabling the conservation of energy.
Hypothalamus - The master controller of the brain and body; integrates bodily signals with their associated feelings and behaviors; regulates speciﬁc functions, including hunger, body rhythms, reward seeking, and aggression.
Hypothesis - A speciﬁc prediction stating what will happen in a study if the theory is correct.
Hysteria - An older term for a group of presumably psychogenic disorders that included a wide variety of physical and psychological symptoms; the term used today is conversion disorder.

I

Iconic memory - A rapidly decaying store of visual sensory information.
Id - The component of personality in Freud’s psychoanalytic theory that is the manifestation of unconscious and instinctual drives and needs.
Imitation - The purposeful copying of a goal-directed behavior.
Implementation intentions - Speciﬁc “if-then” thoughts that cognitively connect a desired action to some triggering event or stimulus.
Implicit attitude - An automatically activated evaluation of a stimulus ranging from positive to negative.
Implicit memory - A form of memory that occurs without intentional recollection or awareness and can be measured indirectly through the inﬂuence of prior learning on behavior.
Implicit racial bias - Differential treatment resulting from the automatic activation, and failure to control, negative attitudes or stereotypes of a racial group.
Impression management - A series of strategies that people use to inﬂuence the impressions that others form of them.
Imprinting - A mechanism for establishing attachment early in life that operates according to a relatively simple rule of attaching to the ﬁrst moving object an organism sees.
In vivo exposure - A key step in the behavioral treatment of a phobia in which the individual is exposed to the phobic stimulus in the real world or through interactive computer programs.
Inattentional blindness - A failure to perceive information that is outside the focus of one’s attention.
Independent self-construal - A notion of the self as a bounded and stable entity that is distinct from others.
Independent variable - The manipulated variable in an experiment.
Infantile amnesia - The inability of adults to retrieve episodic memories from the ﬁrst few years of life.
Inferential statistics - A set of procedures used to estimate whether a pattern of results represents a true relationship or difference in the population.
Informational social influence - Pressure to conform to others’ actions or beliefs based on a desire to behave correctly or gain an accurate understanding of the world.
Informed consent - An application of the ethical principle of autonomy, in which a researcher explains the procedures of a study, including its risks and potential beneﬁts, to the potential participants, who then decide whether to take part.
Inner ear - The innermost part of the ear, where the cochlea resides.
Insight - A sudden conscious change in a person’s understanding of some situation or problem.
Insight learning - A form of learning that occurs without trial and error and thus without clear reinforcement.
Insomnia - A sleep disorder involving chronic difﬁculties with falling or staying asleep.
Instinct - A genetically endowed tendency to behave in a particular way.
Instinctive drift - An animal’s reversion to evolutionarily derived instinctive behaviors instead of demonstrating newly learned responses.
Institutional Review Board (IRB) - A local panel of researchers, teachers, citizens, and others who determine whether a research study lives up to the community’s ethical standards.
Insular lobe - The cortex that is insulated by the overlying cortex; supports the sense of taste and allows perception of the internal organs.
Intelligence - The capability to think abstractly, comprehend complex ideas, reason, plan, solve problems, learn from experience, and acquire new knowledge.
Intelligence quotient (IQ) - A measure of intelligence that is calculated by dividing a child’s mental age by his or her chronological age and then multiplying by 100.
Interdependent self-construal - A notion of the self as deﬁned by one’s connections to other people.
Internal validity - The ability of a study to rule out alternative explanations for a relationship between two variables; one of the criteria for supporting a causal claim.
Interneuron - A neuron that connects neurons and interprets, stores, and retrieves information about the world, allowing you to make informed decisions before you act.
Interpersonal therapy (IPT) - A form of therapy focused on helping patients understand how they interact with others and then learn better ways of interacting and communicating.
Interpretations - In psychoanalysis, explanations of how various thoughts, feelings, and behaviors are linked to prior experiences.
Intrinsically rewarding - Being pursued for its own sake. See also extrinsically rewarding.
Introspect - The process of examining one’s own internal thoughts and feelings.
Ion channels - The channels that allow chemical ions to enter and exit the neuronal membrane to generate the voltage for the resting and action potentials.
Iris - The colored muscle circling the pupil.

J

James–Lange theory - The theory that the subjective experience of emotion is the awareness of one’s own bodily reactions in the presence of certain arousing stimuli.
Journal - A periodical containing peer-reviewed articles on a speciﬁc academic discipline, written for a scholarly audience.
Just-noticeable difference (JND) - The minimum difference required between two stimuli for an observer to detect a difference half the time.

K

Kin selection - An evolved or adaptive strategy of assisting those who share one’s genes, even at personal cost, as a means of increasing the odds of genetic survival.
Kinesthesis - The senses responsible for monitoring the position and movement of the body, including proprioception and the vestibular system.

L

Language - A shared system of symbols, including spoken, written, and signed words and gestures, and a set of rules for how to combine those symbols to communicate meaning.
Language acquisition device - An innate mechanism that linguist Noam Chomsky proposed to explain the process of language acquisition in children. Chomsky argued that the language acquisition device is activated by language exposure and guides language development with little to no explicit teaching from adults.
Latent content - According to Sigmund Freud’s theory, the hidden drives and wishes that are expressed in dreams and behavior but in a disguised form (as the manifest content).
Latent learning - Learning that occurs without either incentive or any clear motivation to learn.
Learned helplessness - A state of passive resignation to an aversive situation that one has come to believe is outside of one’s control.
Learning - An enduring change in behavior resulting from prior experience.
Lens - A membrane at the front of the eye that focuses the incoming light on the retina.
Lesion - An abnormal tissue resulting from disease, trauma, or surgical intervention.
Levels of processing - The multiple levels at which encoding can occur, ranging from shallow to deep.
Lexical hypothesis - The hypothesis that the traits that provide useful ways to differentiate among people’s personality characteristics are necessarily encoded in language.
Lifetime prevalence” - The percentage of people in a certain population who will have a given psychological disorder at any point in their lives.
Limbic system - A system often associated with emotion; it bridges the older, lower brain regions that regulate the body with the newer, higher brain structures more related to complex mental functions.
Linguistic determinism hypothesis (or Whorfian hypothesis) - Benjamin Whorf’s proposal that different languages impose different ways of understanding the world that can shape our thinking.
Lipostatic hypothesis - The hypothesis that adipose tissue plays an important role in governing hunger and regulating longer-term energy balance.
Lobotomy - A type of psychosurgery in which the neurosurgeon severs some or all of the connections between subcortical brain structures such as the thalamus and the frontal lobes.
Locus of control - A person’s perception of what determines his or her outcomes: intrinsic (internal) characteristics or random, external forces.
Long-term memory - A storage level of memory where information can be held for hours to many years and potentially a lifetime.
Long-term potentiation (LTP) - A mechanism that creates enduring synaptic connections, which results in increased transmission between neurons.
Longitudinal design - A methodological approach to studying development that tracks participants across time and compares each participant at different time points.
Loss aversion - The tendency to make choices, including riskier ones, that minimize losses.

M

Magnetic resonance imaging (MRI) - A structural imaging technique that uses magnetic ﬁelds and radio waves to create images of the brain.
Magnetoencephalography (MEG) - The recording of the magnetic ﬁelds produced by the brain’s electrical currents.
Major depressive disorder - A mood disorder characterized by feelings of sadness, emptiness, and anhedonia (diminished interest or pleasure in activities that usually provide pleasure, such as eating or exercising).
Mania - A state of high excitement and energy often characterized by racing thoughts, a feeling of invincibility or omnipotence, and a lack of boundaries or inhibitions.
Manifest content - According to Sigmund Freud’s theory, the visible, surface content of a dream or behavior that disguises the hidden, latent content.
Manipulated variable - A variable whose values the researcher controls, usually by assigning different participants to different levels of that variable.
Mastery orientation - A motivational stance that focuses on learning and improving. See also performance orientation.
Maturation - A series of biological growth processes that enable orderly growth, relatively independently of experience.
Mean - A measure of central tendency that is the arithmetic average of a group of scores.
Measured variable - A variable whose values are simply recorded.
Median - A measure of central tendency that is the middlemost score; it is obtained by lining up the scores from smallest to largest and identifying the middle score.
Meditation - A set of practices used to train a person’s ability to control attention, awareness, and sometimes emotions.
Medulla oblongata - A lower brainstem structure that controls autonomic functions, including heart rate and blood pressure, and reﬂexes like coughing and swallowing.
Memory - The capacity to store and retrieve information in order to facilitate learning.
Menopause - The natural end of menstruation, occurring in middle adulthood.
Mental age - A number that represents the average age at which children perform closest to a given child’s score on an intelligence test.
Mental representation - An internal mental symbol that stands for some object, event, or state of affairs in the world.
Mental set - A mental framework for how to solve a problem based on prior experience with similar problems.
Meta-analysis - A process in which researchers locate all of the studies that have tested the same variables and mathematically average them to estimate the effect size of the entire body of studies.
Metabolic rate - The rate at which the body uses energy.
Metacognition - An awareness and understanding of your own thought processes.
Midbrain - The uppermost region of the brainstem; it includes the tegmentum and substantia nigra, critical for dopamine production.
Middle ear - The portion of the ear containing the eardrum and ossicles.
Mindset - A set of attitudes or beliefs that shape how a person perceives and responds to the world. In the domain of intelligence, a mindset may be an implicit belief about where intellectual ability comes from.
Mirror neurons - Neurons that are active both when performing an action and when the same actions are observed in others.
Misinformation effect - The decreased accuracy of episodic memories because of information provided after the event.
Mode - A measure of central tendency that is the most common score in a batch of scores.
Modeling - A behavioral therapy technique based on observational learning in which patients learn new skills or change their behavior by watching and imitating another person.
Monoamines - A neurochemical class that includes norepinephrine, dopamine, and serotonin; important for ﬁght-or-ﬂight and reward responses.
Monocular cues - Depth information that can be gathered by only one eye.
Monozygotic - Twins who share 100 percent of their genetic material because they developed from the division of a single fertilized egg.
Mood stabilizer - A medication (such as lithium) that treats manic, mixed, or depressive states.
Mood-dependent retrieval - The increased likelihood of remembering when a person is in the same mood during both encoding and retrieval.
Mood-related disorders - Disorders that involve prominent disturbances in a person’s positive and negative feeling states.
Morpheme - The smallest unit of language that carries bits of meaning. Morphemes include words and also word parts like preﬁxes and sufﬁxes that change a word’s meaning.
Motivated forgetting - Willful forgetting of information so that it is less likely to be retrieved later.
Motivational interviewing - A brief, nonconfrontational, client-centered therapy designed to change speciﬁc problematic behaviors such as alcohol or drug use.
Motives - An internal force that leads an individual to behave in a particular way.
Motor development - Changes in the ability to coordinate and perform bodily movements.
Motor neuron - A neuron that sends signals to make the body take action.
Multistore model of memory - A model proposing that information ﬂows from our senses through three storage levels in memory: sensory, short term, and long term.
Myelin sheath - A layer of fatty tissue that covers and insulates an axon to ensure that electrical messages travel fast and meet less resistance.

N

Narcissism - The tendency to have unrealistic and self- aggrandizing views of the self.
Narcolepsy - A sleep disorder in which a person falls asleep suddenly and uncontrollably.
Naturalistic observation - An observational research method in which psychologists observe the behavior of animals and people in their normal, everyday worlds and environments.
Negative cognitive schema - A mental framework in which a person consistently interprets events negatively.
Negative cognitive triad - Three types of dysfunctional beliefs related to oneself (I am unlovable), the world (It’s a cruel world out there), and the future (Things are only going to get worse).
Negative punishment - The removal of a positive stimulus, leading to a decrease in the frequency of a behavior.
Negative reinforcement - The removal of a negative stimulus, leading to an increase in the frequency of a behavior.
Negative symptoms - In psychopathology, an absence of behaviors usually seen in healthy people.
Neocortex - The evolutionarily newest cerebral cortex that is the largest part of the human brain; supports complex functions, including language, thought, problem solving, and imagination.
Nerves - A collection of neurons that carries signals from the body to the brain.
Nervous system - A network of neurons running throughout your brain and body.
Neural plasticity - The brain’s capacity to physiologically modify, regenerate, and reinvent itself constantly over the course of a lifetime.
Neural tube - A tubular structure formed early in the embryonic stage from which the brain and spinal cord develop.
Neurodevelopmental disorder - A disorder that stems from early brain abnormalities.
Neurodevelopmental perspective - This perspective holds that sexual orientation is built into the circuitry of the brain early in fetal development.
Neurodiversity - An appreciation of the range of differences in brain function among individuals.
Neurogenesis - The process by which new brain cells are born in adult brains.
Neurons - The cellular building blocks of the brain.
Neuropsychology - The study of the brain’s workings; done by examining the brain’s altered function following brain damage.
Neuroscience - The study of how nerves and cells send and receive information from the brain, body, and spinal cord.
Neuroticism - A personality dimension associated with heightened levels of negative affect.
Neurotransmitter - The chemical messenger released at the terminal branch to allow communication between neurons.
Night terrors - A sleep disorder occurring during deep sleep that involves dramatic expressions of fear, with accelerated heart rate and respiration.
Non-associative learning - A form of learning that involves a change in the magnitude of an elicited response with repetition of the eliciting stimulus.
Norm of reciprocity - An automatic tendency to help others who have helped in the past or are expected to help in the future.
Normative social influence - Pressure to conform to others’ actions or beliefs in order to gain approval from others or avoid social sanctions.
Not guilty by reason of insanity - A modern legal concept that holds that people are not responsible for criminal behavior if at the time of that behavior they had a mental disorder that left them substantially unable either to understand that what they were doing was wrong or to behave as they knew they should.

O

Object permanence - The awareness that objects continue to exist even when they are temporarily out of sight.
Object relations - A school of psychodynamic thought that emphasizes the real (as opposed to fantasized) relationships an individual has with important others.
Observational learning - A form of learning in which a person observes and imitates a behavior from a model.
Observational research - A descriptive research method in which psychologists measure their variable of interest by observing and recording what people are doing.
Obsession - A recurrent unwanted or disturbing thought.
Obsessive-compulsive disorder (OCD) - An anxiety disorder that manifests itself through obsessions (unwanted and disturbing thoughts) and compulsions (ritualistic actions performed to control the obsessions).
Occipital lobe - A lobe that runs along the back portion of the head; contains the primary visual cortex and is largely devoted to vision.
Olfaction - The sense of smell.
Olfactory bulb - A structure just above the nasal cavity where information is communicated to the primary olfactory cortex via the olfactory tract.
Open science - The practice of sharing one’s data, hypotheses, and materials freely so others can collaborate, use, and verify the results.
Operant conditioning - A mechanism by which our behavior acts as an instrument or tool to change the environment and, as a result, voluntary behaviors are modiﬁed.
Operational definitions - Speciﬁc ways of measuring or manipulating an abstract variable in a particular study.
Operations - In childhood, the manipulation of schemas.
Opponent-process theory - A theory of color perception stating that information from the cones is separated into three sets of opposing or opponent channels in the ganglion cell layer.
Optic nerve - A bundle of axons that converge from the retina and transmit action potentials to the brain.
Ossicles - Three tiny bones in the ear: the hammer, anvil, and stirrup, that act as levers to amplify incoming sound waves.
Outcome efficacy - The belief that if a person can perform a behavior, a desired outcome will result.
Overconfidence bias - The tendency to overestimate the accuracy of one’s knowledge and judgments.
Overregularization errors - A language error made by children that involves extending rules of word formation. These errors reveal children’s understanding of grammar.

P

P-hacking - A family of questionable data analysis techniques, such as adding participants after the results are initially analyzed, looking for outliers, or trying new analyses in order to obtain a p value of just under .05, which can lead to nonreplicable results.
Pain matrix - A distributed network of brain regions, including the amygdala, that respond to many types of pain.
Panic attack - A sudden episode of uncontrollable anxiety, accompanied by terrifying bodily symptoms that include one or more of the following: labored breathing, choking, dizziness, tingling hands and feet, sweating, trembling, heart palpitations, chest pain.
Panic disorder - An anxiety disorder characterized by the occurrence of unexpected panic attacks.
Parasympathetic nervous system - A division of the autonomic nervous system that returns the body to a resting state by counteracting the actions of the sympathetic system.
Parental investment theory - A theory that predicts sex differences in attraction due to the greater time, effort, and risk assumed by women than by men during procreation.
Parietal lobe - A lobe that runs alongside the head above and behind the ears; contains the primary somatosensory cortex, supporting a map of the body’s skin surface and the sense of touch.
Partial reinforcement schedules - A reinforcement schedule in which a behavior is rewarded only some of the time.
Perception - The neural processing of electrical signals to form an internal mental representation inside your brain of what’s on the outside.
Perceptual set - A predisposition that inﬂuences what we perceive based on recent experience or context.
Performance orientation - A motivational stance that focuses on performing well and looking smart. See also mastery orientation.
Peripheral nervous system (PNS) - The system composed of the nerves outside of the brain and spinal cord; connects the parts of the body to the brain.
Person × Situation interactions - A model positing that in order to understand and predict behavior, it is necessary to account for both personal dispositions and the situation people ﬁnd themselves in, as well as the interaction between the two.
Personality - Patterns of thought and behavior that make a person react to certain situations in relatively consistent ways.
Personality disorder - A pattern of behavior and inner experience that (1) deviates markedly from cultural norms and expectations, (2) is inﬂexible and pervasive across a broad range of personal and social situations, and (3) leads to clinically signiﬁcant distress or impairment.
Personality perspective - The psychological perspective that seeks to understand aspects of human behavior that are relatively stable over time and situation.
Phantom limb - The experience of sensations, such as pain, in a limb that no longer exists following its amputation.
Phenotype - The observable characteristics of an individual resulting from the interaction of genotype and environment.
Phi phenomenon - A visual illusion in which the ﬂashing of separate images in rapid succession is perceived as ﬂuid movement.
Phoneme - The smallest unit of language, such as the individual sounds that make up speech.
Phrenology - An early pseudoscience suggesting that mental abilities and personality traits could be read from bumps on the skull.
Pitch - The perceptual quality of sound that makes a ﬂute sound high and a tuba low.
Pituitary gland - The master endocrine gland, located at the base of the brain, that in addition to producing its own hormones regulates hormone production in other glands.
Place theory - A theory of pitch perception stating that different pitches arise from stimulation at different places along the basilar membrane.
Placebo condition - In an experiment, a group or condition in which people expect to receive a treatment but are exposed only to an inert version, such as a sugar pill.
Placebo effect - The inﬂuence of a patient’s beliefs and expectations in bringing about a cure.
Pluralistic ignorance - A situation that can occur when people are collectively unaware of each other’s true attitudes or beliefs.
Point prevalence - The percentage of people in a given population who have a given psychological disorder at any particular point in time.
Pons - An upper brainstem structure that controls breathing and relays sensations, such as hearing, taste, and balance, to the subcortex and cortex.
Population of interest - The full set of cases the researcher is interested in.
Positive psychology - The scientiﬁc study of the factors that make people happy, keep them healthy, and help them manage stress; includes the study of important human experiences, such as hope, courage, and creativity.
Positive punishment - The presentation of a negative stimulus, leading to a decrease in the frequency of a behavior.
Positive reinforcement - The presentation of a positive stimulus, leading to an increase in the frequency of a behavior.
Positive symptoms - In psychopathology, behaviors that are not present in healthy people.
Positron emission tomography (PET) - The injection of radioactive glucose into a person’s bloodstream to measure blood ﬂow associated with higher brain activity or the brain’s use of speciﬁc neurochemicals.
Post-traumatic stress disorder (PTSD) - A trauma- or stressor-related disorder that lasts one month or longer.
Postconventional stage - In Kohlberg’s theory, a period in moral development in which people make moral judgments based on ideals and broad moral principles.
Pragmatics - Rules that govern the practical aspects of language use, such as taking turns, using intonation and gestures, and talking to different types of people.
Preconventional stage - In Kohlberg’s theory, a period in moral development in which people make moral judgments based on self-interest, such as avoiding punishments and gaining rewards.
Prejudice - A negative attitude toward a group or members of a group.
Premack principle - The idea that activities individuals frequently engage in can be used to reinforce activities that they are less inclined to do.
Preparedness - The species-speciﬁc biological predisposition to learn some associations more quickly than other associations.
Preregistration - A researcher’s public statement of a study’s expected outcome before collecting any data.
Primary appraisal - A person’s perception of the demands or challenges of a given situation.
Primary auditory cortex - The region of the brain, located in the temporal lobe, where sound is processed.
Primary motor cortex - The cortex that is responsible for voluntary movements.
Primary olfactory cortex - The region of the brain, located in the anterior temporal lobe, where smell is processed.
Primary reinforcers - A consequence that is innately pleasurable and/or satisﬁes some biological need.
Primary sensory areas - The ﬁrst regions of the cerebral cortex to receive signals from a sensory organ via its sensory nerve.
Primary sex characteristics - Body structures, such as ovaries, testes, and external genitalia, that make sexual reproduction possible.
Primary somatosensory cortex - The region of the brain where the processing of touch sensations occurs.
Priming - The increased ability to process a stimulus because of previous exposure.
Proactive interference - The disruptive effect of prior learning on the recall of new information.
Procedural memory - A type of implicit memory related to the acquisition of skills.
Projection - A defense mechanism in which people, instead of acknowledging it in themselves, see others as possessing a disliked trait or feeling.
Projective test - A form of clinical assessment in which a person responds to unstructured or ambiguous stimuli; it is thought that responses reveal unconscious wishes and conﬂicts.
Proprioception - The sensory system responsible for awareness of body positions.
Prosopagnosia - A visual disorder in which individuals are unable to recognize the identity of faces.
Prospective memory - Memory for things we need to do in the future.
Prototype - A best example or average member of a concept that incorporates most of the features most commonly associated with it.
Pseudoscience - A collection of beliefs or practices mistakenly thought to be based on valid science.
Psychedelics - Drugs that distort perception and can trigger hallucinations (sensations without any sensory input), changes in moods, thoughts, sense of self, and even feelings of insight.
Psychoactive drugs - Chemical substances that alter a person’s thoughts, feelings, or behaviors by inﬂuencing the activity of neurotransmitters in the nervous system.
Psychoanalysis - A method of therapy, developed by Sigmund Freud, asserting that clinical symptoms arise from unconscious conﬂicts rooted in childhood.
Psychodynamic approaches - Therapeutic approaches that derive from psychoanalytic theory, which asserts that clinical symptoms arise from unconscious conﬂicts rooted in childhood.
Psychogenic - Resulting from a psychological cause rather than from organic damage to the nervous system.
Psychological disorder - A clinically signiﬁcant disturbance in an individual’s cognition, emotional regulation, or behavior that is usually associated with signiﬁcant distress or disability in social, occupational, and other important activities.
Psychological science - The scientiﬁc study of mind and behavior.
Psychology - The scientiﬁc study of mind and behavior.
Psychopathology - (1) The scientiﬁc study of psychological disorders, or (2) the disorders themselves.
Psychophysics - The study of the relationship between the physical characteristics of environmental stimuli and our mental experience of them.
Psychosurgery - Brain surgery performed to alleviate symptoms of psychological disorders that cannot be alleviated using psychotherapy, medication, or other standard treatments; the surgery removes sections of the brain or disconnects them from each other.
Psychotropic medications - Medications that control, or at least moderate, the symptoms of some psychological disorders.
Puberty - The period of sexual maturation during which males and females become capable of reproduction.
Punishment - A consequence that decreases the likelihood that a behavior will be repeated.
Pupil - A hole in the iris where light enters the eye.

R

Random assignment - A procedure used in experimental research in which a random method is used to decide which participants will receive each level of the independent variable.
Random sampling - A way of choosing a sample of participants for a study in which participants are selected without bias, for example, by dialing random digits on the telephone or pulling names out of a hat.
Rapid eye movement (REM) sleep - A stage of sleep characterized by rapid eye movements, brain activity similar to wakefulness, faster heart and breathing rates, inability to move the skeletal muscles, and dreams.
Rapport - A client’s sense of trust in, respect for, and comfort with the treatment provider.
Rational emotive behavioral therapy - A form of cognitive therapy, pioneered by Albert Ellis, in which the therapist actively challenges the patient’s irrational beliefs.
Realistic group conflict theory - A theory asserting that negative intergroup attitudes develop whenever groups compete against one another for access to the same scarce resources.
Reappraisal - A type of emotion regulation that involves altering the meaning of a potentially emotion-eliciting situation in order to alter one’s emotional response to that situation. See also suppression.
Reciprocal determinism - The idea that personality guides cognition about the world in ways that can shape the environments people choose, serving to reinforce or amplify their personality.
Recognition - A form of retrieval that relies on identifying previously seen or experienced information.
Reconsolidation - Reactivation of consolidation by retrieving a memory, making the memory susceptible to change.
Reflexes - Automatic patterns of motor responses that are triggered by speciﬁc types of sensory stimulation.
Refractory period - The period of time required for a neuron to return to its resting state before it can ﬁre another action potential.
Rehearsal - The holding of information in the brain through mental repetition.
Reinforcement - A consequence that increases the likelihood that a behavior will be repeated.
Reliability - The degree to which a measure yields consistent results each time it is administered.
REM behavior disorder (RBD) - A sleep disorder that involves acting out one’s dreams because the paralysis that normally occurs during REM sleep is absent or incomplete.
REM rebound - The tendency to spend more time in REM sleep if deprived of it on previous nights.
Reminiscence bump - A time of prominent memory making between adolescence and early adulthood.
Repetitive transcranial magnetic stimulation (rTMS) - An emerging biological treatment for depression that involves applying rapid pulses of magnetic stimulation to the brain from a coil held near the scalp.
Replication - When a study is conducted more than once on a new sample of participants, and obtains the same basic results.
Repolarization - The portion of the action potential during which the neuron returns to its resting potential.
Representativeness heuristic - A mental shortcut for judging the likelihood of something based on how well it represents some category.
Repression - A defense mechanism in which the ego keeps unwanted feelings, thoughts, and memories below the level of conscious awareness.
Resilience - One’s ability to effectively cope with stressful events and return to baseline levels quickly.
Resistance - In psychoanalysis, a patient’s self-censorship or avoidance of certain topics.
Restructuring - The process of reorganizing one’s understanding of a problem to facilitate a solution.
Reticular formation - A structure that runs through the brainstem and is connected to many parts of the brain; plays a central role in arousal and attention.
Retina - A surface on the back of the eye that contains the photoreceptor cells.
Retrieval - The process of bringing to mind previously encoded and stored information.
Retrieval cues - Information related to stored memories that helps bring the memories back to mind.
Retroactive interference - The disruptive effect of new learning on the recall of old information.
Retrograde amnesia - A form of amnesia in which access to memories prior to brain damage is impaired, but the individual can store new experiences in long-term memory.
Retrospective memory - Memory for things we have done in the past.
Rods - Photoreceptor cells that primarily support nighttime vision.
Rumination - The process of repetitively turning emotional difﬁculties over and over in the mind.

S

Sample - The group who participated in research, and who belong to the larger group (the population of interest) that the researcher is interested in understanding.
Savant syndrome - A syndrome in developmentally disabled individuals that involves the presence of unusual talents that contrast with low levels of general intelligence.
Scaffolding - A process of promoting cognitive development by actively challenging and supporting children as they attempt things that are beyond their current capabilities.
Scatterplot - A ﬁgure used to represent a correlation, in which each dot usually represents a study participant, the x-axis represents one variable, and the y-axis represents the other variable.
Schachter–Singer theory - The theory that emotion arises from the interpretation of bodily responses in the context of situational cues.
Schemas - Concepts or mental models that represent our experiences.
Schizophrenia - A psychological disorder characterized by a loss of contact with reality and a breakdown of the normal functions of the mind, leading to bizarre perceptions.
Scientific method - The process of basing one’s conﬁdence in an idea on systematic, direct observations of the world, usually by setting up research studies to test ideas.
Secondary appraisal - A person’s perception of his or her ability to deal with the demands of a given situation.
Secondary reinforcers - A learned pleasure that acquires value through experience because of its association with primary reinforcers.
Secondary sex characteristics - Nonreproductive body structures, such as hips, torsos, voices, and body hair, that make the body look more “adult.”
Selective attention - The act of focusing one’s awareness onto a particular aspect of one’s experience, to the exclusion of everything else.
Selective serotonin reuptake inhibitor (SSRI) - A medication (such as Prozac, Zoloft, and Paxil) that increases serotonin turnover in the brain and is widely used to treat depression, eating disorders, anxiety disorders, and many other disorders.
Self-actualization - The process of fulﬁlling one’s true potential by gaining a sense of personal autonomy, accepting oneself, and accepting other people.
Self-concept - The broad network of mental representations that a person has of him or herself.
Self-control - The attempt to modify automatic or “default” responses in a particular situation.
Self-determination theory - A theory positing that well-being and success are most likely to be achieved when a person’s environments support three key motivations: autonomy, competence, and relatedness.
Self-efficacy - The belief that one can successfully execute a behavior linked to a desired outcome.
Self-fulfilling prophecy (or Pygmalion effect) - A cycle by which others’ beliefs or our own can affect behavior in ways that make the beliefs true.
Self-referential encoding - Encoding based on an event’s relation to our self-concept, which leads to enhanced memory for the event.
Self-report measure - A standardized clinical assessment tool that consists of a ﬁxed set of questions that a patient answers.
Self-serving attributions - The attributions people make for their own behaviors or outcomes: We tend to make dispositional attributions for positive events but situational attributions for negative events.
Self-serving biases - Characteristic ways of processing information to maintain a positive attitude toward the self.
Self-transcendence - The desire to further a cause that goes beyond the self. See also hierarchy of motives.
Semantic memory - Explicit memory supporting knowledge about the world, including concepts and facts.
Sensation - The process by which our sensory organs receive stimulus energies from the environment and transduce them into the electrical energy of the nervous system.
Sensitive period - An early period in the life of an organism during which it is especially sensitive to and able to learn from speciﬁc information in its environment.
Sensitization - A form of non-associative learning by which an organism becomes more sensitive, or responsive, to a repeated stimulus.
Sensory memory - A storage level of memory that holds sensory information on the order of milliseconds to seconds.
Sensory neuron - A neuron that carries information from the outside world and within the body to the brain.
Sequential design - A methodological approach to studying development that tracks multiple age groups across time and compares different age groups to one another, as well as compares participants to themselves at different time points.
Sexual selection - An evolutionary perspective positing that men and women develop distinct proﬁles of personality traits because of the different reproductive challenges they face.
Shallow encoding - Encoding based on sensory characteristics, such as how something looks or sounds.
Shaping - The process by which random behaviors are gradually changed into a desired target behavior.
Short-term memory - A storage level of memory where information can be held brieﬂy, from seconds to less than a minute.
Signal detection theory - An approach to measuring thresholds that takes into account both the intensity of the stimulus and psychological biases for a more accurate assessment.
Single-cell recording - A measurement of the electrical activity of a single neuron.
Size constancy - The phenomenon whereby the brain adjusts its perception of distance in order to perceive an object’s actual size as constant, taking into account changes in retinal size.
Sleep - A regularly occurring state of altered consciousness that happens when arousal is very low.
Sleep apnea - A sleep disorder in which a person’s breathing is interrupted because of obstructions in the airway or problems with the brain’s control of breathing.
Sleep hygiene - A regimented routine at bedtime that allows one’s body to learn cues for sleep.
Sleepwalking - A sleep disorder that involves walking or performing other behaviors while in deep sleep.
Social anxiety disorder - An anxiety disorder characterized by extreme fear of being watched, evaluated, and judged by others.
Social clock - A set of norms that govern the typical timing of life milestones like marriage, parenthood, and retirement.
Social facilitation - An enhancement of the dominant behavioral response when performing a task in the mere presence of others; easy or well-learned tasks are performed better, but difﬁcult or novel tasks are performed worse.
Social identity - A sense of identity that is rooted in group memberships.
Social identity theory - A theory that explains why people develop a more positive attitude toward their own ingroup than toward outgroups.
Social learning theory - A theory of how people’s cognitions, behaviors, and dispositions are shaped by observing and imitating the actions of others.
Social loafing - The tendency for individuals to expend less effort on a task when they are doing it with others rather than alone.
Social norms - The patterns of behavior, traditions, and preferences that are tacitly sanctioned by a given culture or subculture.
Social psychological perspective - The psychological perspective that studies the ways in which immediate social contexts inﬂuence thoughts, feelings, and behaviors, independent of personality.
Social psychology - The study of how the immediate social context as well as broader cultural environments inﬂuence people’s thoughts, feelings, and actions.
Social referencing - A process of using others’ facial expressions for information about how to react to a situation.
Social role theory - A theory positing that the roles people ﬁnd themselves in can profoundly shape their personality.
Social support - The degree to which people believe they can turn to other people for information, help, advice, or comfort.
Sociocultural view of development - Lev Vygotsky’s proposal that the child’s mind grows through social interaction with knowledgeable others.
Socioemotional selectivity theory - Laura Carstensen’s theory that our perception of how much time we have left in life leads us to value emotional over informational goals.
Sociometer theory - A theory positing that people use self- esteem, a judgment of self-worth, to assess the degree to which they are accepted by others.
Somatic nervous system (SNS) - The system that allows us to feel external sensations from and control volitional movement of the body.
Somatosensory homunculus - A depiction of how the body is represented by the brain, proportional to the amount of cortex devoted to each body part.
Spacing effect - The enhanced ability to remember information when encoding is distributed over time.
Specific phobia - A marked fear of or anxiety about a particular object or situation, such as snakes, bridges, lightning, dentists, or blood.
Spinal cord - The major bundle of nerves, encased in your spine, that connects your body and your brain.
Split-brain procedure - The severing of the corpus callosum to reduce the spread of seizures across brain hemispheres.
Spontaneous improvement - Clinical improvement not associated with a clinical intervention.
Spontaneous recovery - The reappearance of an extinct behavior after a delay.
Stages - Distinct segments of an organism’s life with sharp differences or discontinuities between them.
Standard deviation - A variability statistic that calculates how much, on average, a batch of scores varies around its mean.
Standardization - A process of making test scores more meaningful by deﬁning them in relation to the performance of a pretested group.
State-dependent retrieval - The increased likelihood of remembering when a person is in the same state during both encoding and retrieval.
Statistical significance - A process of inference that applies rules of logic and probability to estimate whether the results obtained in a study’s sample are the same in a larger population.
Stem cell - A cell that has not yet undergone gene expression to differentiate into a specialized cell type such as a skin cell, liver cell, or neuron.
Stereotype threat - A concern that one’s performance or behavior might conﬁrm a negative stereotype about one’s group.
Stereotypes - Mental representations or schemas that summarize the beliefs and/or associations we have for a group of people.
Stimulants - Drugs that increase activity levels in the nervous system.
Storage - The maintenance of information in the brain for later access.
Strength model of ego control - According to this model, self- regulatory efforts draw on a ﬁnite pool of cognitive resources. Repeated self-regulatory demands may deplete these resources, leading to failures of self-control. See also ego depletion.
Stress - A physiological response to an environmental event that is perceived as taxing or even exceeding one’s ability to adapt.
Subliminal perception - A form of perception that occurs without conscious awareness.
Subsyndromal disorders - Versions of psychological disorders that don’t meet the DSM-5 criteria for diagnosis but that may nonetheless cause signiﬁcant problems.
Superego - The component of personality in Freud’s psychoanalytic theory that represents the internalized cultural rules and ideals to guide our moral conscience.
Superstitious conditioning - A form of operant conditioning in which a behavior is learned because it was coincidentally reinforced, but has no actual relationship with reinforcement.
Suppression - A type of emotion regulation that involves inhibiting one’s ongoing emotion-expressive behavior. See also reappraisal.
Symbolic racism - The tendency to redirect one’s prejudice toward a racial or ethnic group to the policies that might beneﬁt that group.
Symbolic representation - The use of words, sounds, gestures, visual images, or objects to stand for other things.
Sympathetic nervous system - A division of the autonomic nervous system that acts on blood vessels, organs, and glands in ways that prepare the body for action, especially in life-threatening situations.
Sympathetic-adreno-medullary (SAM) axis - A physiological system that governs the body’s immediate response to a stressful event, enabling the ability to ﬁght or ﬂee.
Symptom - A physical or mental feature that may be regarded as an indication of a particular condition or psychological disorder.
Synapse - The gap where a sending neuron communicates with the dendrites or cell body of the receiving neuron.
Syndrome - A cluster of physical or mental symptoms that are typical of a particular condition or psychological disorder and that tend to occur simultaneously.
Syntax - Grammatical rules that govern how words and phrases combine into well-formed sentences.

T

Tactile sense - The sense of touch.
Telehealth - The use of telephone, videoconferencing, internet, and streaming media technologies to support health care at a distance.
Temperament - A person’s characteristic patterns of emotion and behavior that are evident from an early age and argued to be genetically determined.
Temporal lobe - A lobe that runs alongside the ears; contains the primary auditory cortex and is responsible for the ability to hear and understand language.
Teratogens - Environmental agents that can interfere with healthy fetal development.
Terminal branch - The part of the neuron that converts electrical signals into chemical messages to other neurons.
Terror management theory - A theory positing that self- esteem allows people to cope with existential terror stemming from their awareness of their own mortality.
Thalamus - A subcortical structure deep in the middle of the brain; communicates information to and from all of the sensory systems except the olfactory (smell) system, regulating alertness and consciousness.
Theory - A set of propositions explaining how and why people act, think, or feel.
Theory of mind - The understanding that we and other people have minds, that these minds represent the world in different ways, and that these representations can explain and predict how others will behave.
Theory-data cycle - The process of the scientiﬁc method, in which scientists collect data that can either conﬁrm or disconﬁrm a theory.
Therapeutic alliance - The relationship between therapist and patient that helps many patients feel hopeful and supported.
Third wave therapies - The latest generation of cognitive-behavioral therapies, including acceptance and commitment therapy as well as mindfulness-based stress reduction.
Third-variable problem - For a given observed relationship between two variables, an additional variable that is associated with both of them, making the additional variable an alternative explanation for the observed relationship.
Threat reactivity - A cardiovascular pattern of responding to a situation whereby the heart pumps out more blood but the vasculature constricts, preventing efﬁcient circulation through the body.
Thrifty gene hypothesis - The evolutionary hypothesis that natural selection has favored individuals with efﬁcient metabolisms that maximize fat storage.
Tip-of-the-tongue phenomenon - A failure to retrieve information despite conﬁdence that it is stored in memory.
Token economies - A behavioral therapy technique based on operant conditioning in which patients’ positive behaviors are reinforced with tokens that they can exchange for desirable items.
Tonotopic organization - The arrangement of the auditory cortex such that nearby frequencies are processed near each other in the brain, resulting in a sound map.
Transcranial direct current stimulation (TDCS) - A gentler form of neurostimulation that uses very low levels of direct current delivered via electrodes on the head to stimulate brain function, such as enhancing hand-eye coordination.
Transcranial magnetic stimulation (TMS) - A temporary and reversible disruption or enhancement of cortical brain function that allows scientists to study brain regions and their functions.
Transduction - The transformation of sensory stimulus energy from the environment into neural impulses.
Transference - The tendency to treat one person as if they possess the traits or characteristics of another more familiar person. For example, in psychotherapy, clients might respond to a therapist in ways that resemble the dynamic they have with major ﬁgures in their own lives.
Trauma- and stressor-related disorders - Psychological disorders that are triggered by an event that involves actual or threatened death, serious injury, or sexual violation.
Trephination - An early therapy for mental disorders that involved cutting a hole in the skull.
Triangular theory of love - A model that speciﬁes passion, intimacy, and commitment as distinct elements that combine in various ways that lead to different types of love.
Trichromatic theory - A theory of color perception stating that three types of cone cells, each most sensitive to a speciﬁc wavelength of light, work together to produce our perception of a multicolored world.
Type A personality - A label used to describe a collection of traits that include being highly competitive and driven, hot- tempered and hostile, and urgently focused on time and time management.
Type B personality - A label used to describe a collection of traits that include being reﬂective, creative, and less competitive.
Typical antipsychotics - First-generation antipsychotic medications that block the neurotransmission of dopamine.

U

Unconditioned response (UR) - The response that is automatically generated by the unconditioned stimulus.
Unconditioned stimulus (US) - A stimulus that produces a reﬂexive response without prior learning.
Unconscious - The part of our mental life that inﬂuences our thoughts, feelings, and actions that we cannot directly observe and of which we are unaware.
Unihemispheric sleep - A pattern of sleep in which only one half (or hemisphere) of the brain experiences slow-wave sleep at a time, while the other half remains awake.
Unit bias - The amount of food that is regarded as a single serving.

V

Vagal nerve stimulation - An emerging biological treatment for depression that involves electrically stimulating the vagus nerve with a small battery-powered implant.
Validity - The appropriateness or accuracy of a conclusion or decision.
Variability - The extent to which the scores in a batch differ from each other.
Variable - Something of interest that varies from person to person or situation to situation.
Variable-interval schedule - A reinforcement schedule based on an amount of time between rewards that varies around a constant average.
Variable-ratio schedule - A reinforcement schedule in which an average number of behaviors are required before a reward is given.
Vertical transmission - The transmission of skills from parent to offspring.
Vestibular system - The sensory system primarily responsible for balance.
Vicarious reinforcement - A form of modeling in which the learner acquires a conditioned response merely by observing another participant being conditioned.
Visual association cortex - The region of the brain where objects are reconstructed from prior knowledge and information collected by the feature detectors.
Voltage threshold - The voltage necessary for a neuron to start an action potential.

W

Wait-list control condition - In randomized clinical trials, a control condition in which patients receive delayed treatment rather than no treatment. Before being treated, they are compared to patients treated earlier.
Wavelength - The distance between any two consecutive crests or troughs of a wave.
Weapons effect - A phenomenon whereby simple exposure to a gun or weapon can increase aggressive responses by bringing violent thoughts to mind.
Web-based therapy - A nontraditional form of therapy in which the therapy is conducted over the internet.
Weberʼs law - The observation that the likelihood of perceiving a stimulus change is proportional to the magnitude of the stimuli.
Wechsler Adult Intelligence Scale (WAIS) - An intelligence test composed of many subtests that can be combined into a single composite to capture overall ability. Scores on separate subtests of the WAIS can be used to identify relative strengths and weaknesses that are useful to educators and therapists.
WEIRD samples - Research participants from Western, Educated, Industrialized, Rich, and Democratic backgrounds.
Willpower - The ability to engage in self-control.
Withdrawal - Unpleasant physical symptoms that result when a person is physically dependent on a drug and its effects wear off.
Working memory - A component of memory that allows for both the short-term storage and manipulation of information in real time.

Z

Zygote - A fertilized egg, formed by the union of a sperm and egg. publish

The Grand Conversation

Table of Contents

Glossary

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

R

S

T

U

V

W

Z

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