1,800+ MCAT terms, defined.

Tolerance is a reduced response to a drug after repeated use, so a larger dose is needed for the original effect. Along with withdrawal, it is a marker of physiological dependence. Part of it can be conditioned to environmental cues.

Assortative mating is non-random partner choice in which people pair with others who resemble them, such as in education, age, ethnicity, religion, or values. The testable point: similarity tends to predict attraction and partnering, not...

Cued recall is retrieving a stored item when given a hint, such as a category, first letter, or one word of a studied pair, instead of producing it with no help. It usually beats free recall but is typically harder than recognition, and...

General intelligence (g) is Spearman's idea that one broad underlying mental ability contributes to performance on many different cognitive tasks, because scores on varied tests tend to correlate positively. The key contrast is with Gard...

Strong linguistic determinism is the strong form of the Sapir-Whorf hypothesis: language determines thought, so people cannot think about ideas their language has no words for. The MCAT contrasts it with the weaker linguistic relativity...

Guilt is a negative, self-conscious emotion felt when you judge that your behavior broke your own moral standards or harmed someone. Testable point: guilt usually targets a specific act, while shame targets the whole self. Erikson's stag...

Mitral cells are the main output neurons of the olfactory bulb. They receive input from olfactory receptor neurons in glomeruli and send axons along the olfactory tract to olfactory cortex and limbic areas, without the usual thalamic rel...

Sensitization is a form of nonassociative learning in which a strong, noxious or threatening stimulus makes an organism respond more strongly to later stimuli, often including different, milder ones. It is the counterpart of habituation,...

Moral reasoning is the thinking a person uses to decide and justify what is right or wrong. In Kohlberg's theory it develops through three levels: preconventional, conventional and postconventional. The exam scores the reasoning given, n...

Prospective memory is remembering to carry out an intended action in the future, such as mailing a letter or taking a pill at a set time. It contrasts with retrospective memory, recall of past events or information. Testable point: it re...

Retinal disparity is the small difference between the images that fall on the two retinas because the eyes sit apart. The brain uses it as a binocular depth cue: the larger the disparity, the closer the object, and distant objects produc...

Behavioral genetics studies how genetic and environmental differences among people contribute to differences in behavior and traits, using twin, adoption and family studies. Most testable: heritability describes variation within a popula...

Consciousness-altering (psychoactive) drugs change awareness, mood, or perception by altering neurotransmitter activity at synapses. The MCAT sorts them into depressants, stimulants, opiates, and hallucinogens, and tests which neurotrans...

In Erikson's psychosocial theory, generativity vs. stagnation is the crisis of middle adulthood: contributing to and guiding the next generation (generativity) versus self-absorption and feeling unproductive (stagnation). Testable point:...

Group polarization is the tendency of group discussion to push a shared initial leaning to a more extreme position than the members' average view before talking. Two accounts explain it: social comparison (normative) and persuasive argum...

Identity formation is the process of building a stable sense of who you are, shaped by personal exploration and social influences. The MCAT ties it to Erikson's identity vs. role confusion in adolescence and to Marcia's four identity sta...

In Erikson's psychosocial theory, identity vs. role confusion is the adolescent crisis (roughly ages 12 to 18) of forming a coherent sense of self. Success gives a stable identity (virtue: fidelity); failure leaves uncertainty about who...

Impression formation is the process of combining cues about a person, such as appearance, behavior and traits, into one overall judgment. The most testable point is that information is not weighed equally: early information often counts...

In Erikson's psychosocial theory, industry vs. inferiority is the fourth stage, covering roughly ages 6 to 12. Children who master school and social tasks and are encouraged gain a sense of competence; repeated failure or discouragement...

Initiative vs. guilt is Erikson's third psychosocial stage, in early childhood (about ages 3–6), when children start planning and beginning activities. Encouragement builds purpose; repeated criticism can leave guilt. It follows autonomy...

Integrity vs. despair is Erikson's eighth and final psychosocial stage, in late adulthood. People review their lives and either accept them with a sense of wholeness (integrity) or feel regret and fear of death (despair). Success yields...

Intimacy vs. isolation is Erikson's sixth psychosocial stage, in young adulthood (roughly 18 to 40). The task is forming close, committed relationships; success brings the virtue of love, while failure can leave a person lonely and isola...

Kinesthetic sense (kinesthesia) is the awareness of body position and movement, from receptors in muscles, tendons, and joints. Many texts treat it as interchangeable with proprioception; some limit it to movement. It differs from the ve...

Need theories explain motivation as behavior aimed at satisfying needs. Maslow's hierarchy ranks needs from physiological to self-actualization, with lower needs generally taking priority. Drive-reduction theory says a need creates a dri...

Out-group dynamics are the patterns in how people perceive and treat members of groups they do not belong to, compared with their own in-group. The most testable point: people tend to favor the in-group and see out-group members as more...

The body's coordinated reaction to a perceived threat: a fast sympathetic–adrenal medulla surge (epinephrine, norepinephrine) and a slower HPA axis release of cortisol. Most testable: Selye's alarm, resistance, exhaustion stages, and chr...

On the MCAT, antisocial usually means antisocial personality disorder: a long-standing pattern of disregarding and violating others' rights, with deceit, impulsivity, and little remorse. It is a Cluster B disorder, and it does not mean s...

The episodic buffer is a component of Baddeley's working memory model. It is a temporary, limited-capacity store that binds information from the phonological loop, the visuospatial sketchpad and long-term memory into one unified episode....

A neural impulse is the action potential: a brief reversal of membrane potential that travels down an axon once a neuron reaches threshold. The neuron fires fully or not at all, so a stronger stimulus raises the firing rate, not the size...

Retrograde amnesia is the loss of memories formed before a brain injury or disease, while the ability to form new memories may be intact. Older memories are often better preserved than recent ones. It is the opposite of anterograde amnes...

Tip links are tiny filaments connecting the tip of each stereocilium on a hair cell to its taller neighbor. Bending toward the tallest stereocilia stretches them and opens mechanically gated ion channels, so the hair cell depolarizes; be...

In Vygotsky's sociocultural theory, the zone of proximal development is the gap between what a learner can do alone and what they can do with help from a more knowledgeable person. Learning is most effective on tasks in this zone, suppor...

Ambivalent (resistant) attachment is an insecure infant attachment style in which the child is very distressed when the caregiver leaves and is not easily soothed on return, seeking contact yet resisting it. It is linked to inconsistent...

A critical period is a limited window in development when a particular experience, such as language exposure, is needed for an ability to develop normally. If the input is missing, the deficit often lasts. A sensitive period is the softe...

Deep sleep is slow-wave sleep, the non-REM stage (stages 3 and 4 in older systems, N3 in the newer one) marked by high-amplitude, low-frequency delta waves. It is the hardest stage to wake from, and sleepwalking and night terrors tend to...

A randomized controlled trial randomly assigns participants to a treatment group or a control group, then compares outcomes. Random assignment spreads confounders evenly, so it best supports a causal claim. This is a research-design idea...

In Piaget's theory, the preoperational stage (roughly ages 2 to 7) is when children use symbols such as words and pretend play but cannot yet perform logical mental operations. The most testable points are egocentrism and failure of cons...

Random mating means individuals pair without regard to the genotype or phenotype in question, so pairings depend only on how common each type is. It is one condition for Hardy-Weinberg equilibrium. Nonrandom mating, such as assortative m...

The actual self is the set of attributes you believe you currently have, one part of self-concept. The MCAT contrasts it with the ideal self (who you wish to be) and the ought self (who you feel you should be). Gaps between them are link...

Non-associative learning is a change in response to a repeated stimulus without linking it to another stimulus or a consequence. The two forms tested are habituation (response decreases) and sensitization (response increases).

Aversive control is changing behavior with unpleasant stimuli, either by punishing a behavior to make it less likely or by negatively reinforcing one (escape or avoidance) to make it more likely. Negative reinforcement is not punishment:...

Awareness is knowing about your own thoughts, feelings and sensations and about events around you. It is the core of consciousness. The MCAT treats it as a matter of degree, from alert wakefulness through drowsiness and sleep, with alter...

The inferior colliculus is a midbrain structure that relays auditory information from the brainstem up to the thalamus and helps orient the head toward sounds. Most testable point: it is for hearing, while the superior colliculus is for...

Klüver–Bucy syndrome is a cluster of behavioral changes, including loss of fear and aggression, hyperorality and hypersexuality, that follows bilateral temporal lobe damage involving the amygdala. The most testable point is that amygdala...

Passive aggression is the indirect expression of hostility through seemingly cooperative or neutral behavior, such as procrastinating, sulking, or deliberate inefficiency, instead of open confrontation. It is aimed at the real source of...

Social psychology is the study of how an individual's thoughts, feelings, and behavior are influenced by other people and the social situation. The most testable point is that situational factors, such as group size or authority, often s...

Situational means explained by a person's external circumstances rather than by traits. In attribution theory, a situational (external) attribution credits behavior to the environment or context. Testable point: observers often overlook...

The accessory olfactory bulb receives input from the vomeronasal organ and processes pheromones in many mammals, sending signals to the amygdala and hypothalamus. In humans it is generally considered vestigial, though some researchers de...

Cognitive flexibility is the ability to shift between tasks, mental sets, or strategies and to adapt thinking when rules or circumstances change. It is an executive function linked to the prefrontal cortex. The exam often contrasts it wi...