Glossary of Psychological Terms
Definitions of terms used in psychology, psychometric testing and occupational assessment, organised alphabetically.
Babble
The repetitive, meaningless consonant-vowel sounds infants produce from around 6 months of age, generally regarded as a universal precursor to speech that occurs even in infants who are deaf. See also: language acquisition.
Babinski reflex
A reflex in which stroking the sole of the foot causes the big toe to extend upward and the other toes to fan out, normal in infants but, if present in adults, a sign of neurological damage to the corticospinal tract. Named after French neurologist Joseph Babinski.
Balance theory
A theory of attitude and cognitive consistency, most associated with Fritz Heider, holding that people prefer relationships between their own attitudes, other people, and objects to be internally consistent (“balanced”), and experience tension when they are not.
Bandwagon effect
The tendency to adopt a belief, opinion or behaviour because other people are doing so, independent of one's own evaluation of its merits. Studied in social psychology and consumer behaviour, and closely related to conformity and social proof.
Bard-Cannon theory
See Cannon-Bard theory. An older ordering of the same term found in some older glossaries; the theory holds that emotional experience and physiological arousal occur simultaneously and independently, both triggered by the thalamus, rather than arousal causing emotion.
Basic mistrust
In Erik Erikson's stage theory of psychosocial development, the negative outcome of the first stage (trust vs. mistrust), arising when an infant's early caregiving is inconsistent or unreliable, leaving a lasting sense that the world is unpredictable or unsafe.
Basic personality
A concept from culture-and-personality anthropology (associated with Abram Kardiner) describing the personality structure shared by members of a given culture as a result of common early childhood experiences and institutions.
Basic trust
In Erikson's theory, the positive outcome of the first psychosocial stage, developed when an infant's needs are met consistently and reliably, forming the foundation for later confidence in relationships and the world.
Battle fatigue
An earlier term for the psychological exhaustion and stress reactions experienced by combat soldiers, now more commonly understood under the diagnosis of post-traumatic stress disorder (PTSD). Also historically called “shell shock” in World War I.
Bayley Scales of Infant Development
A standardised assessment, developed by Nancy Bayley, used to evaluate the motor, cognitive, language and behavioural development of infants and toddlers, widely used in developmental psychology and paediatrics.
Becoming
A term used by personality theorist Gordon Allport to describe the ongoing, lifelong process of personal growth and self-realisation, as distinct from viewing personality as a fixed, static structure.
Bedlam
Originally the popular name for Bethlem Royal Hospital in London, one of the oldest psychiatric institutions in Europe, notorious for its harsh treatment of patients; the word has since entered general usage to mean uproar or chaotic confusion.
Behaviour
Any observable action or response of an organism, ranging from simple reflexes to complex social conduct. The central subject matter of behaviourism, and more broadly one of the core units of analysis across psychology alongside cognition and affect.
Behaviour modification
The application of learning principles — particularly operant conditioning, using reinforcement and punishment — to change specific, observable behaviours, widely used in clinical, educational and organisational settings.
Behaviour therapy
A form of psychotherapy that applies learning-theory principles (classical and operant conditioning) to treat psychological problems by directly targeting maladaptive behaviours, rather than focusing on unconscious conflict as psychoanalysis does. Often used alongside cognitive therapy as cognitive-behavioural therapy (CBT).
Behavioural genetics
The scientific study of the role genetics plays in individual differences in behaviour, personality, and psychological traits, typically using twin and adoption studies to estimate the relative contributions of genetic and environmental factors.
Behaviourism
A school of psychology, founded by John B. Watson and later developed by B. F. Skinner, holding that psychology should study only observable behaviour and its relationship to environmental stimuli, rejecting introspection and unobservable mental states as valid objects of scientific study.
Belief system
An organised, interrelated set of beliefs, attitudes and values that a person or group holds and uses to interpret and respond to the world, studied in social and cognitive psychology in relation to attitude change and persuasion.
Bell-shaped curve
A common informal name for the normal distribution, a symmetric probability distribution in which most values cluster around a central mean and taper off evenly toward both extremes; foundational to psychometrics and the statistical scoring of psychological tests.
Bender-Gestalt Test
A neuropsychological test, developed by Lauretta Bender, in which a respondent copies a series of geometric figures; used to assess visual-motor integration and to screen for possible brain damage or developmental delay.
Berdache
An older anthropological term, now considered outdated and largely replaced by terms such as Two-Spirit, historically used to describe individuals in some Indigenous North American cultures who occupied a distinct gender role outside the male/female binary.
Bernreuter Personality Inventory
An early self-report personality questionnaire, developed by Robert Bernreuter in the 1930s, measuring traits such as neuroticism, introversion-extraversion and self-sufficiency; historically significant as one of the first multi-trait personality inventories.
Beta rhythm
A pattern of brain wave activity, detected by EEG, with a frequency of roughly 13–30 Hz, associated with an alert, actively thinking waking state, as distinct from the slower alpha rhythm associated with relaxed wakefulness.
Biased sample
In statistics and research methodology, a sample that is not representative of the population it is meant to describe, because some members were more likely to be included than others, leading to systematically skewed results.
Bilateral transfer
The transfer of a motor skill learned with one limb (for example, the right hand) to the opposite, untrained limb, studied in motor learning research as evidence that some aspects of skill learning are represented centrally rather than purely in the trained muscles.
Bimodal distribution
A probability or frequency distribution with two distinct peaks (modes) rather than one, often suggesting that the data actually reflect two separate underlying groups or processes rather than a single homogeneous population.
Binet scale
An early standardised test of intelligence, developed by Alfred Binet and Théodore Simon in France in 1905 to identify children needing additional educational support; the basis for later intelligence scales including the Stanford-Binet.
Binocular disparity
The slight difference between the images projected onto each eye's retina, caused by their separated horizontal positions; the brain uses this disparity as a primary cue for depth perception and stereoscopic vision.
Binocular fusion
The process by which the brain combines the two separate, slightly different images received from each eye into a single, unified three-dimensional visual perception.
Biofeedback
A technique in which a person is given real-time information (feedback) about a physiological process, such as heart rate, muscle tension or skin temperature, usually via electronic monitoring, in order to learn to consciously influence and regulate that process, often to reduce stress or manage pain.
Biorhythms
A popular but scientifically unsupported theory proposing that physical, emotional and intellectual functioning follow fixed, predictable cyclical patterns from birth; distinct from circadian rhythms, which are genuine biological cycles with strong empirical support.
Bipolar disorder
A mood disorder characterised by alternating episodes of mania or hypomania (elevated mood, energy and impulsivity) and depression (low mood and energy), previously known as manic-depressive illness.
Birth order
The sequential position of a child among their siblings (firstborn, middle child, youngest), theorised by Alfred Adler and others to influence personality development, though empirical support for strong, consistent birth-order effects is mixed.
Birth trauma
A concept, associated particularly with psychoanalyst Otto Rank, proposing that the physical and psychological experience of being born is itself a source of anxiety that influences later personality and emotional development.
Black box
A metaphor, used particularly by behaviourists, for the mind or brain treated as an unobservable system: rather than speculating about its unseen internal workings, the approach focuses only on observable inputs (stimuli) and outputs (behaviour).
Blacky pictures
A projective personality test for children, consisting of cartoon drawings of a dog named Blacky in various family scenarios, designed to elicit responses revealing unconscious attitudes toward psychoanalytic themes such as sibling rivalry and toilet training.
Bleuler, Eugen (1857-1939)
A Swiss psychiatrist who coined the term “schizophrenia” in 1908, replacing the earlier term “dementia praecox,” and who made influential contributions to the classification and understanding of psychotic disorders.
Blind spot
The small area of the retina where the optic nerve exits the eye, containing no light-sensitive photoreceptor cells and therefore unable to detect visual stimuli; normally unnoticed because the brain fills in the gap using surrounding visual information.
Body image
A person's subjective perception, thoughts and feelings about their own physical appearance and body, which may or may not correspond closely to their actual physical characteristics, and which is studied in relation to self-esteem and eating disorders.
Body language
The communication of information, attitude or emotion through non-verbal physical behaviour — posture, gesture, facial expression and eye contact — studied as a component of overall interpersonal communication.
Bonding
The process of forming a close emotional attachment, most commonly used to describe the early relationship between an infant and its primary caregiver, considered foundational to later social and emotional development. See also: attachment.
Boomerang effect
In persuasion research, a phenomenon in which an attempt to change someone's attitude or behaviour produces the opposite of the intended effect, often because the target perceives the attempt as a threat to their freedom of choice (reactance).
Brain
The organ within the skull responsible for regulating bodily functions and generating thought, emotion, perception, memory and behaviour, composed of billions of interconnected neurons organised into specialised structures and regions.
Brain damage
Injury to brain tissue, caused by trauma, stroke, disease, oxygen deprivation or toxic exposure, which can impair cognitive, sensory, motor or emotional functioning depending on the location and extent of the damage.
Brain localisation
The theory and body of evidence that specific psychological functions (such as language, memory or vision) are associated with specific, identifiable regions of the brain, rather than being distributed uniformly throughout the whole organ.
Brain potential
A small electrical voltage change generated by neural activity in the brain, measurable at the scalp using EEG; event-related potentials (ERPs) are brain potentials time-locked to a specific stimulus or event, widely used in cognitive neuroscience research.
Brain stimulation
The direct activation of brain tissue using electrical, magnetic or chemical means, used both as a research tool to study brain function and, in techniques such as electroconvulsive therapy (ECT) or transcranial magnetic stimulation (TMS), as a clinical treatment.
Brainstorming
A group technique for generating a large quantity of ideas or solutions to a problem, popularised by advertising executive Alex Osborn, based on the principle of deferring judgement and criticism during the idea-generation phase.
Brainwashing
A colloquial and largely non-clinical term for the systematic, often coercive attempt to fundamentally alter a person's beliefs, attitudes or loyalties, typically through isolation, psychological pressure and manipulation of information.
Breakthrough
In psychotherapy, a sudden, significant moment of insight or emotional release in which a client gains new understanding of a problem or unblocks previously resisted material, often producing rapid therapeutic progress.
Brightness constancy
A form of perceptual constancy in which an object is perceived as having a stable, unchanging brightness or lightness despite variations in the actual amount of light reflected from it under different lighting conditions.
