1,800+ MCAT terms, defined.

Covert orienting is shifting attention to a location or object without moving the eyes or head, like aiming a mental spotlight. In cueing tasks, a valid cue speeds responses to a target at that location, and an invalid cue slows them.

Overt orienting is shifting attention by physically moving the eyes, head, or body toward a stimulus so its image falls on the fovea. Covert orienting shifts attention while gaze stays fixed. Testable point: overt versus covert depends o...

Spinal nerves are the 31 pairs of peripheral nerves that attach to the spinal cord and connect it to the body. Each is mixed: sensory axons enter through the dorsal root and motor axons leave through the ventral root. Testable point: spi...

Albert Bandura is the psychologist who developed social learning theory: people can learn by observing and imitating a model, without being directly reinforced themselves. His Bobo doll experiment is the classic example. He also proposed...

Echoic memory is the sensory register for sound. It briefly holds a large amount of raw auditory input, typically about 3–4 seconds, and the information decays unless attention moves it into short-term (working) memory. It lasts longer t...

Hans Eysenck was a trait theorist who described personality with a few broad, largely heritable dimensions: extraversion–introversion and neuroticism, later adding psychoticism. Testable point: in his arousal theory, extraverts have lowe...

The ideal self is the person you want to be, built from your aspirations and goals, as opposed to the real (actual) self. A large gap between them tends to bring distress and lower self-esteem. Rogers calls this incongruence. Higgins tie...

Imitation is copying the behavior of a model, the core of observational learning in Bandura's social learning theory. Learning can occur without direct reinforcement, and seeing a model rewarded or punished (vicarious reinforcement) chan...

The incus (anvil) is the middle of the three middle-ear ossicles. It relays eardrum vibrations from the malleus to the stapes, which pushes on the cochlea's oval window. Testable point: the order malleus → incus → stapes transmits and am...

Lesion studies infer what a brain region does by observing behavior or cognition after that region is damaged, whether by injury, stroke, surgery, or deliberate damage in animals. The testable point: a lost function suggests the region c...

The malleus (hammer) is the middle-ear bone attached to the eardrum. It passes vibrations to the incus and then the stapes, which drives the oval window of the cochlea. Testable point: the order of the sound path, and that the ossicles a...

A phobia is an anxiety disorder of intense, persistent fear of a specific object or situation, out of proportion to the real danger, with avoidance. The MCAT explains it by classical conditioning (acquisition) and negative reinforcement...

The anterior chamber is the fluid-filled space at the front of the eye, between the cornea and the iris. It holds aqueous humor, which nourishes the cornea and lens and helps maintain eye pressure. Light passes through it on its way to t...

Change blindness is failing to notice a large change in a visual scene when it happens during a brief interruption, such as a blink, cut, or flicker. It shows that perception relies on selective attention, so people often miss changes in...

Cognitive distortions are habitual, automatic, exaggerated thought patterns, such as catastrophizing or all-or-nothing thinking, that bias how a person reads events and can maintain depression and anxiety. The MCAT tests naming the disto...

Ecological validity is how well a study's setting, tasks, and procedures resemble real-life conditions, so its findings can be expected to apply outside the research setting. Tightly controlled lab studies often gain internal validity bu...

Evolutionary game theory models how behavioral strategies spread in a population when the fitness payoff of a strategy depends on what others are doing. A strategy that no rare alternative can beat once it is common is an evolutionarily...

A flashbulb memory is a vivid, detailed memory of the circumstances in which you learned of a surprising, emotionally significant event. Emotional arousal (amygdala activity) strengthens encoding, but these memories are often less accura...

The frustration-aggression hypothesis says that blocking a person's goal produces frustration, which raises the urge to aggress. The original 1939 version claimed a strict link; Berkowitz's revision says frustration only makes aggression...

Pretend play is make-believe in which a child lets an object, action, or role stand for something else, such as a banana for a phone. In Piaget's theory it shows symbolic thought, a hallmark of the preoperational stage (about ages 2 to 7).

Harlow raised infant rhesus monkeys with a wire surrogate that gave milk and a cloth surrogate that gave none; the infants clung mostly to the cloth one. It shows attachment depends strongly on contact comfort, not just feeding, challeng...

Kinaesthesia (kinesthesia) is the sense of the position and movement of body parts, based on receptors in muscles, tendons and joints. Many texts treat it as proprioception; others use proprioception for position and kinesthesia for move...

Parvocellular cells are the small cells of the lateral geniculate nucleus (and the retinal ganglion cells feeding them) that carry color and fine detail. They start the "what" pathway to the temporal lobe. Magnocellular cells, in contras...

Attentional capture is the involuntary pull of attention toward a stimulus, a form of bottom-up (stimulus-driven) processing, even when you were focused on something else. Sudden, intense or personally relevant stimuli, like a loud noise...

Aversive conditioning reduces attraction to a stimulus or behavior by pairing it with something unpleasant. In the classical account, the target (such as alcohol paired with nausea) becomes a conditioned stimulus that triggers avoidance;...

Ego depletion is the proposal that self-control draws on a limited mental resource, so using willpower on one task leaves less for a later one. The classic result is reduced persistence on a second task, but replications and motivation-b...

An extinction burst is a temporary increase in the frequency, intensity, or variety of a previously reinforced behavior right after reinforcement is first withheld. It signals that extinction is under way, and the behavior typically decl...

Gender schema theory says children learn gender through cognitive schemas, which are mental frameworks that organize information about what is male or female. These schemas then guide attention, memory, and behavior. Testable point: gend...

Motivational interviewing is a collaborative, client-centered counseling style that helps people resolve ambivalence and build their own motivation to change a behavior. Testable point: the counselor uses open-ended questions and reflect...

Optimism bias is the tendency to judge your own chances of good outcomes as higher, and of bad outcomes as lower, than the evidence or other people's outcomes support. The exam treats it as a systematic error in judgment about future eve...

Parallel processing is the brain's simultaneous analysis of different features of a stimulus, such as color, shape, and motion, through separate pathways. Serial processing works one step at a time. Automatic tasks tend to be parallel; e...

Social desirability bias is the tendency of respondents to answer in ways they think will be viewed favorably, overreporting good behavior and underreporting bad. It threatens the validity of self-report data, especially on sensitive top...

Spontaneous recovery is the reappearance of an extinguished conditioned response when the conditioned stimulus is presented again after a rest period. The recovered response is typically weaker than the original. It suggests extinction s...

Synaptic pruning is the normal elimination of little-used synapses during development, while frequently used connections are kept and strengthened. It makes neural circuits more efficient, and the testable idea is "use it or lose it": ex...

A token economy is an operant conditioning system in which desired behaviors earn tokens (points, stickers, chips) that can later be exchanged for backup reinforcers like privileges or treats. Tokens are secondary (conditioned) reinforce...

Intellectualization is a defense mechanism in which a person handles a threatening or painful situation by focusing on abstract facts and logic, so the feelings are avoided. The testable cue is cool, detached, analytical talk about a dis...

Disgust is a basic emotion of revulsion toward something offensive or contaminating. Ekman counted it among six basic emotions (with happiness, sadness, anger, fear, surprise) whose facial expressions are widely recognized across culture...

A psychological disorder is a persistent pattern of thoughts, emotions, or behaviors that is deviant, distressing, and dysfunctional, and in some cases dangerous. The testable point is that being unusual is not enough; distress or impair...

Broca's area is a region of the left frontal lobe in most people that controls the production of speech. Damage causes Broca's (expressive, nonfluent) aphasia: effortful, halting speech with comprehension largely intact. The MCAT contras...

The auditory cortex is the region of the temporal lobe that receives and interprets sound information relayed from the thalamus (medial geniculate nucleus). Each ear projects to both hemispheres, so damage to one side usually does not ca...

The sclera is the tough, white, opaque outer layer of the eyeball. It protects the eye, maintains its shape, and anchors the eye muscles. It is continuous with the clear cornea at the front, and light enters through the cornea, not the s...

Self-image is a person's description of their own traits, abilities, and roles. Many texts treat it as one component of self-concept, and some use the two terms interchangeably. Testable point: self-image describes, while self-esteem eva...

Brain waves are rhythmic electrical patterns from large groups of cortical neurons, recorded by EEG and classified by frequency. Wakefulness shows fast, low-amplitude waves (beta, then alpha when relaxed). Deeper sleep brings slower, hig...

The endocrine system is a network of glands that release hormones into the blood to act on distant target cells that have matching receptors. Compared with the nervous system, its effects are usually slower but longer-lasting, and the hy...

The somatosensory cortex is the strip of parietal lobe along the postcentral gyrus that processes touch, pressure, temperature, pain, and body position. Its body map gives more cortex to sensitive areas like the lips and fingers, not to...

A variable-ratio schedule is an operant conditioning schedule that reinforces a response after an unpredictable number of responses, averaging around a set value (slot machines are the classic example). It typically produces a high, stea...

Accuracy is how close a measurement or finding is to the true value. In research design it is closely tied to validity, meaning the measure captures what it claims to. A measure can be reliable (consistent) yet inaccurate, because a syst...

Ecstasy is MDMA, a synthetic amphetamine derivative that textbooks classify as a stimulant, a hallucinogen, or both. It mainly increases serotonin in the synapse by promoting its release and blocking its reuptake, which produces euphoria...

Myelin is a fatty insulating sheath wrapped in segments around many axons. It is made by oligodendrocytes in the CNS and Schwann cells in the PNS, and it speeds action potentials by saltatory conduction. Loss of myelin, as in multiple sc...

The reticular activating system (RAS) is a network of neurons in the brainstem's reticular formation that projects through the thalamus to the cortex to regulate arousal, wakefulness, and alertness. Most testable: it sets the level of ar...