1,800+ MCAT terms, defined.

Erikson's psychosocial stages are eight lifespan stages, each built around a social crisis between two outcomes, such as trust vs mistrust. Know the order and pairings: vignettes are matched to a stage by age and task, though ages are ap...

Orgasm is the peak of sexual arousal and the third phase of the Masters and Johnson sexual response cycle (excitement, plateau, orgasm, resolution). Most testable: resolution follows it, and males typically have a refractory period in wh...

Episodic memory is explicit (declarative) long-term memory for personally experienced events tied to a particular time and place, such as your last birthday. The MCAT pairs it with semantic memory, which holds general facts; both are exp...

Functional attitudes theory (Daniel Katz) says people hold attitudes because the attitudes meet psychological needs. The four functions are knowledge, instrumental (adaptive), ego-defensive, and value-expressive. The usual question gives...

The macula (macula lutea) is the central region of the retina around the fovea, rich in cones, giving sharp color vision at the center of gaze. The same word also names the hair-cell patches in the utricle and saccule that sense linear a...

Personality theories are frameworks that explain why people show stable patterns of thought, feeling, and behavior. The MCAT's main families are psychoanalytic, humanistic, trait, social cognitive, behaviorist, and biological, and the us...

Subliminal stimuli are stimuli below the absolute threshold, so they are not consciously perceived, yet they can still be processed and can bias later responses through priming. Testable point: lab effects are real but small and brief, a...

Vygotsky's sociocultural theory holds that cognitive development is driven largely by social interaction and cultural tools, especially language. The most testable idea is the zone of proximal development: tasks a child cannot yet do alo...

Tension is not a formally defined MCAT term in psychology or sociology. It is a descriptive word for an unpleasant state of arousal, discomfort or strain that tends to motivate a change. The most testable case is cognitive dissonance, wh...

An electroencephalogram (EEG) records the brain's electrical activity through scalp electrodes, mainly from summed postsynaptic potentials in the cortex. Most testable: as sleep deepens, waves slow and grow taller (beta, alpha, theta, de...

Opponent-process theory says color is coded by paired channels (red–green, blue–yellow, black–white) in which the two members oppose each other in the same cells. It explains negative afterimages. It works alongside trichromatic theory:...

Maslow's hierarchy is a humanistic theory of motivation that ranks needs in a pyramid: physiological, safety, love and belonging, esteem, self-actualization. Lower needs generally must be reasonably met before higher ones drive behavior,...

Anthropomorphism is attributing human traits, emotions, or intentions to nonhuman animals, objects, or natural events. The testable point is that it is an interpretive bias in studying animal behavior, so researchers describe observable...

In Freud's psychosexual theory, the Electra complex is a girl's unconscious desire for her father and rivalry with her mother during the phallic stage (about ages 3–6). The name comes from Jung, as a counterpart to the Oedipus complex. I...

The hindbrain is the posterior brain division next to the spinal cord, made up of the medulla, pons and cerebellum. It runs basic survival functions, balance and movement coordination. Most testable: cerebellum for coordination, medulla...

Insomnia is a sleep disorder with persistent difficulty falling asleep, staying asleep, or waking too early, despite adequate opportunity to sleep, and it impairs daytime functioning. The MCAT tests telling it apart from narcolepsy, slee...

Creativity is the ability to produce ideas or solutions that are both novel and useful. The MCAT ties it to divergent thinking, which generates many possible answers, as opposed to convergent thinking, which narrows to one best answer.

In Freud's psychoanalytic theory, the death instinct (often called Thanatos) is an unconscious drive toward aggression, destruction and a return to a lifeless state. It opposes the life instinct, Eros. Aggression or self-destructive beha...

The phonological loop is the part of Baddeley and Hitch's working memory model that briefly holds verbal and auditory information by silently rehearsing it. It is separate from the visuospatial sketchpad, so two verbal tasks interfere wi...

A reinforcement schedule is the rule for when a behavior is reinforced in operant conditioning, set by number of responses (ratio) or elapsed time (interval), and fixed or variable. Most testable: variable-ratio typically gives the highe...

Universal emotions are basic emotions, commonly listed as happiness, sadness, anger, fear, surprise and disgust, whose facial expressions are recognized across many cultures. The testable point: the expressions are largely shared, but cu...

A conditioned stimulus (CS) is a formerly neutral stimulus that, after repeated pairing with an unconditioned stimulus, comes to trigger a conditioned response. The testable point: the CS is learned and predicts the US, so it must be pre...

The oval window is the membrane-covered opening between the middle ear and the fluid-filled cochlea. The stapes pushes on it, turning ossicle vibrations into pressure waves in cochlear fluid. Its small area compared with the eardrum conc...

Umami is the savory taste, the fifth basic taste alongside sweet, sour, salty, and bitter. It is triggered mainly by glutamate, an amino acid found in meats, aged cheese, and MSG. The testable point: taste is a chemical sense, and umami...

Drive-reduction theory proposes that a physiological need (like hunger or thirst) creates an internal state of tension called a drive, and behavior is motivated to reduce it and restore homeostasis. The testable point: it explains motiva...

Persuasion is changing someone's attitudes or beliefs with a message. In the elaboration likelihood model, the central route relies on careful thought about argument quality and tends to give longer-lasting change; the peripheral route r...

Social influence is the way a person's thoughts, feelings, and behavior change because of the real or imagined presence of others. The MCAT sorts it into conformity (matching a group), compliance (answering a request), and obedience (fol...

The stress response is the body's physiological and psychological reaction to a stressor, driven by a fast sympathetic pathway (epinephrine) and a slower HPA axis that releases cortisol. Most testable: it follows appraisal of the threat,...

Prosody is the rhythm, stress, pitch, and loudness of speech, which carry emotion and intent beyond the words themselves. Testable point: in most people prosody is processed largely by the right hemisphere, while core language areas (Bro...

The arcuate nucleus is a hypothalamic cluster of neurons that senses hunger and satiety hormones in the blood. Ghrelin activates its appetite-stimulating neurons, while leptin and insulin inhibit those neurons and activate its appetite-s...

Conditioning is learning in which behavior changes through association or consequences. Classical conditioning links two stimuli; operant conditioning links a behavior to reinforcement or punishment. Most testable: reinforcement, includi...

Standard deviation (SD) measures how spread out scores are around the mean, in the same units as the scores. A larger SD means more variability. In a roughly normal distribution, about 68% of scores fall within 1 SD of the mean and about...

A positive control is a group or condition given a treatment already known to produce the expected effect. It shows the study's procedure and measure can detect an effect. If it fails to show the effect, a null result for the new treatme...

Semantic memory is the part of explicit (declarative) memory that stores general knowledge, such as facts, concepts and word meanings, usually without recalling when or where they were learned. The key contrast is with episodic memory, w...

Anomia is difficulty retrieving the word for a known object, person, or place, while comprehension, fluency, and repetition are fairly well preserved. Its pure form is anomic aphasia, often linked to left temporal or parietal damage. It...

Nociceptors are sensory receptors, usually free nerve endings, that respond to potentially damaging stimuli such as extreme heat, strong pressure or chemicals from injured tissue. Fast myelinated A-delta fibers carry sharp pain; slower u...

Reciprocal determinism is Albert Bandura's model in which personal factors (thoughts, beliefs, self-efficacy), behavior, and environment influence one another in both directions. The testable point is that causation runs in loops, so a p...

A cross-sectional study is an observational design that measures variables in a sample at one point in time, often comparing groups such as different age groups. It is quick and inexpensive, but it generally cannot show causation or time...

The sensory register is the first stage of memory in the Atkinson–Shiffrin model. It briefly holds raw sensory input, as iconic (visual) memory for a fraction of a second and echoic (auditory) memory for a few seconds. Input that is atte...

Autonomy is the capacity to govern oneself and make one's own choices. The MCAT most often uses it in Erikson's second stage, autonomy versus shame and doubt (toddler years), and in self-determination theory, where autonomy is a basic ne...

In Piaget's theory, the concrete operational stage (roughly ages 7 to 11) is when children begin to reason logically about real, tangible objects and events. The most testable point is conservation: a child understands that quantity stay...

Convergence is a binocular depth cue: the eyes rotate inward to fixate a near object, and the brain uses feedback from the eye muscles to judge distance. The more the eyes turn inward, the closer the object seems. It needs both eyes.

Ethology is the scientific study of animal behavior in natural settings, with emphasis on its evolutionary and adaptive value. The MCAT links it to largely innate behaviors such as fixed action patterns triggered by sign stimuli, in cont...

Exogenous means arising from outside the person or system. In psychology it usually describes attention pulled automatically by an external stimulus (bottom-up, stimulus-driven), unlike endogenous attention, which a person directs volunt...

Generalization is when a response learned to one stimulus also occurs to similar stimuli. In conditioning, the more a new stimulus resembles the original CS or discriminative stimulus, the stronger the response tends to be. Its counterpa...

A lexicon is the stored mental dictionary of all the words a person knows, including their meanings, sounds, and spellings. In MCAT language questions, it is the vocabulary component of language, separate from grammar (syntax), which gov...

Neurotic describes someone high in neuroticism, the Big Five trait of emotional instability: a tendency toward anxiety, worry, moodiness and other negative emotions. The testable point is that this is one end of a continuous trait (oppos...

Syntax is the set of grammar rules for arranging words into meaningful phrases and sentences in a language. The MCAT contrasts it with semantics (meaning): a sentence can be syntactically correct yet meaningless, or understandable despit...

Spatial processing is the brain's analysis of where objects are, how they are oriented, and how to act on them. The MCAT ties it to the dorsal "where/how" visual stream and the parietal lobe, in contrast to the ventral "what" stream in t...

The absolute threshold is the minimum stimulus intensity needed for a person to detect it, conventionally defined as the intensity detected 50% of the time. It varies between people and conditions, and it is distinct from the difference...