MCAT: Psychological, Social, and Biological Foundations

Comprehensive, concise MCAT terms and definitions for the P/S section of the MCAT

Absolute Threshold

The minimum intensity of a stimulus required for a person to detect it fifty percent of the time

Difference Threshold

The smallest change in a stimulus intensity that can be detected fifty percent of the time, also called the just noticeable difference

Weber Law

The principle stating that the just noticeable difference between two stimuli is a constant proportion of the original stimulus intensity

Signal Detection Theory

A framework explaining how individuals distinguish important signals from background noise while accounting for decision making biases

Sensory Adaptation

A decrease in responsiveness to a constant stimulus over time due to receptor fatigue

Parallel Processing

The brain ability to process color, motion, shape, and depth simultaneously

Top Down Processing

Sensory perception guided by higher level cognitive processes, expectations, and prior knowledge

Bottom Up Processing

Sensory perception built sequentially from individual incoming sensory details without prior context

Trichromatic Theory

The theory that color vision relies on three types of retinal cones sensitive to short, medium, and long wavelengths

Opponent Process Theory

This theory states that our vision and emotions work through opposite pairs. When one side of the pair turns on, the other side turns off. This concept explains how we see color afterimages and why intense emotional highs are often followed by lows.

Proprioception

The sense of body awareness and spatial position derived from receptors in muscles, tendons, and joints

Vestibular Sense

The sensory system located in the inner ear that contributes to balance and spatial orientation

Habituation

A form of non associative learning where repeated exposure to a stimulus leads to a decreased response

Dishabituation

The recovery of a habituated response after a change in stimulus or presentation of a novel stimulus

Classical Conditioning

A learning process in which a neutral stimulus becomes associated with an unconditioned stimulus to elicit a conditioned response

Extinction

The gradual weakening and disappearance of a conditioned response when the conditioned stimulus is presented alone

Spontaneous Recovery

The unexpected reappearance of an extinguished conditioned response after a rest period

Stimulus Generalization

The tendency for stimuli similar to a conditioned stimulus to evoke a similar conditioned response

Stimulus Discrimination

The ability to differentiate between a conditioned stimulus and other unconditioned stimuli

Operant Conditioning

A method of learning that occurs through rewards and punishments for voluntary behavior

Positive Reinforcement

The addition of a desirable stimulus to increase the frequency of a behavior

Negative Reinforcement

The removal of an aversive stimulus to increase the frequency of a behavior

Positive Punishment

The addition of an unpleasant stimulus to decrease the frequency of a behavior

Negative Punishment

The removal of a desirable stimulus to decrease the frequency of a behavior

Fixed Ratio Schedule

A reinforcement schedule where a behavior is reinforced after a set number of responses

Variable Ratio Schedule

A reinforcement schedule where a behavior is reinforced after an unpredictable number of responses, yielding high resistance to extinction

Fixed Interval Schedule

A reinforcement schedule where a behavior is reinforced after a set amount of time has elapsed

Variable Interval Schedule

A reinforcement schedule where a behavior is reinforced at unpredictable time intervals

Shaping

An operant conditioning technique where successive approximations of a desired complex behavior are reinforced

Escape Learning

A behavior executed to terminate an ongoing aversive stimulus

Avoidance Learning

A behavior executed to prevent an expected aversive stimulus from occurring

Observational Learning

Learning that occurs by watching and imitating the behavior of others

Mirror Neurons

Specialized neurons that fire both when performing an action and when observing another individual perform that same action

Working Memory

A cognitive system responsible for temporarily holding and manipulating information during complex tasks

Explicit Memory

Declarative memory requiring conscious recall, encompassing semantic facts and episodic personal experiences

Implicit Memory

Non declarative memory operating without conscious awareness, including procedural skills and emotional conditioning

Semantic Memory

A category of explicit memory involving factual knowledge, concepts, and general world information

Episodic Memory

A category of explicit memory involving personally experienced life events

Procedural Memory

A category of implicit memory involving motor skills and physical habits

Priming

An implicit memory effect where exposure to one stimulus influences the response to a subsequent stimulus

Chunking

A memory strategy involving the grouping of individual items into larger meaningful units

State Dependent Memory

The phenomenon where memory retrieval is most effective when an individual is in the same psychological or physiological state as during encoding

Context Dependent Memory

The phenomenon where memory retrieval is improved when tested in the same environmental context as encoding

Serial Position Effect

The tendency to recall the first items, known as the primacy effect, and last items, known as the recency effect, in a list best

Anterograde Amnesia

The inability to form new long term memories following brain trauma

Retrograde Amnesia

The loss of memories formed prior to the onset of brain injury

Proactive Interference

When older memories hinder the recall of newly learned information

Retroactive Interference

When newly learned information hinders the recall of older memories

Misinformation Effect

The impairment of memory recall caused by exposure to misleading post event information

Source Amnesia

Misattributing the origin of a remembered memory or fact while retaining the factual content

Long Term Potentiation

The persistent strengthening of synapses based on recent activity patterns, forming the biological basis of memory

Schema

A mental framework or cognitive structure that helps organize and interpret information

Assimilation (Psychological)

The cognitive process of fitting new information into pre existing mental schemas. (e.g., A toddler sees a sheep for the first time and calls it a "dog" because it's four-legged and furry).

Accommodation

The cognitive process of modifying existing mental schemas to incorporate new information

Sensorimotor Stage

The first Piagetian stage from birth to two years focused on sensory input and motor actions, ending with object permanence

Object Permanence

The understanding that objects continue to exist even when they cannot be directly seen

Preoperational Stage

The second Piagetian stage from 2 to 7 years characterized by egocentrism, symbolic thought, and lack of conservation

Egocentrism

The inability of a child to take or understand another person perspective

Concrete Operational Stage

The third Piagetian stage from seven to eleven years characterized by logical thought regarding physical events and understanding conservation

Conservation

The understanding that physical quantity remains constant despite changes in shape or appearance

Formal Operational Stage

The final Piagetian stage beginning around age twelve characterized by abstract thinking and systematic hypothesis testing

Fluid Intelligence

The ability to reason abstractly, solve novel problems, and adapt quickly, independent of acquired knowledge

Crystallized Intelligence

The accumulated knowledge, vocabulary, and learned skills acquired through education and experience

Functional Fixedness

A cognitive bias limiting an individual to using an object only in the way it is traditionally used

Availability Heuristic

Estimating the likelihood of an event based on how easily similar instances come to mind

Representativeness Heuristic

Categorizing something based on how well it matches a typical mental prototype

Confirmation Bias

The tendency to search for and favor information that confirms pre existing beliefs

Broca Area

A region in the left frontal lobe responsible for motor speech production

Broca Aphasia

A condition resulting from frontal lobe damage causing non fluent, halting speech despite intact comprehension

Wernicke Area

A region in the left temporal lobe involved in language comprehension

Wernicke Aphasia

A condition resulting from temporal lobe damage causing fluent but meaningless speech and impaired language comprehension

Linguistic Relativity Hypothesis

The idea that the structure of a language influences its speakers world view and cognitive processes

Circadian Rhythm

Internal biological cycles lasting approximately twenty four hours that regulate sleep and alertness

REM Sleep

A sleep stage marked by rapid eye movements, vivid dreaming, muscle atonia, and high brain activity (beta waves)

James Lange Theory

The emotion theory proposing that physiological arousal occurs first and directly triggers emotional experience

Cannon Bard Theory

The emotion theory stating that physiological arousal and emotional experience occur simultaneously and independently

Schachter Singer Theory

The emotion theory stating that emotion relies on both physiological arousal and a cognitive appraisal of context

Limbic System

A brain network including the amygdala, hippocampus, thalamus, and hypothalamus involved in processing emotion and memory

Amygdala

A limbic system structure primarily responsible for processing fear, aggression, and emotional memories

General Adaptation Syndrome

Hans Selye stress response model consisting of alarm, resistance, and exhaustion stages

Primary Stress Appraisal

The initial evaluation of an environment to determine if a stressor is irrelevant, benign, or threatening

Secondary Stress Appraisal

The evaluation of personal coping resources available to manage an identified stressor

Drive Reduction Theory

The theory that motivation arises from physiological needs that create internal drives pushing organisms to restore homeostasis. This theory acts as an internal push. Unmet biological needs create tension (like hunger or thirst) that pushes you to act

Incentive Theory

The theory that motivation is driven by external rewards and reinforcement. The motivation is from external rewards and goals (like money or praise) that "pull" us toward specific behaviors, even if we have no biological deficit.

Yerkes Dodson Law

The principle that performance increases with physiological arousal up to an optimal point, beyond which performance declines

Maslow Hierarchy of Needs

A motivational model organizing human needs from basic physiological survival up to self actualization

Cognitive Dissonance Theory

The psychological discomfort experienced when holding conflicting cognitions, motivating a change in attitude or behavior

Elaboration Likelihood Model (Central and Peripheral Route)

A theory of persuasion involving two routes

First Route: Used when people care about the topic and have time to think. Focuses on facts, logic, and strong arguments. Results in lasting attitude and behavior change.

Second Route:Used when people do not care or are distracted.Focuses on surface cues like speaker looks, music, or simple rules of thumb. Results in quick, but often temporary, attitude change.

Self Efficacy

An individual belief in their personal capability to execute behaviors necessary to achieve specific outcomes

Locus of Control

The degree to which people believe they have control over outcomes, categorized as internal or external

Freud Id Ego and Superego

The primary personality components representing primal instincts, realistic mediation, and moral ideals

Erikson Psychosocial Stages

A developmental framework proposing eight life conflicts centered on social self development from infancy through old age.1. Infancy, 0 -1.5 years — trust vs mistrust. 2. Early Childhood (1.5 to 3 years) – Autonomy vs. Shame and Doubt. 3. Preschool (3 to 6 years) – Initiative vs. Guilt. 4. School Age (6 to 12 years) – Industry vs. Inferiority. 5. Adolescence (12 to 18 years) – Identity vs. Role Confusion. 6. Young Adulthood (18 to 40 years) – Intimacy vs. Isolation. 7. Middle Adulthood (40 to 65 years) – Generativity vs. Stagnation. 8. Late Adulthood (65+ years) – Integrity vs. Despair

Kohlberg Stages of Moral Development

A framework categorizing moral reasoning into preconventional punishment focus, conventional law focus, and postconventional ethical focus. The vast majority of adults do not progress past Stage 4

Level 1: Pre-Conventional (Self-Interest Focus)

Morality determined by personal consequences (rewards and punishments).

• Stage 1: Obedience & Punishment: Avoiding negative consequences ("Don't steal or you'll go to jail").

• Stage 2: Self-Interest / Exchange: Seeking personal rewards or trade-offs ("What's in it for me?").

Level 2: Conventional (Social Order Focus)

Morality determined by social approval and adherence to rules/laws.

• Stage 3: Interpersonal Conformity: Seeking approval from peers/family ("Good boy/girl" mentality).

• Stage 4: Law & Order: Upholding duty, authority, and societal laws to prevent chaos. (Where the vast majority of adults remain).

Level 3: Post-Conventional (Abstract Ethical Focus)

Morality determined by universal rights and personal conscience, which can supersede laws.

• Stage 5: Social Contract: Laws are adaptable tools meant to protect human rights; if a law fails to do so, it should be changed.

• Stage 6: Universal Ethical Principles: Morality is driven by an internalized, abstract sense of universal justice and human dignity, regardless of legal or personal risk.

Looking Glass Self

Charles Cooley concept that an individual self concept is built from perceiving how others view and judge them

Socialization

The lifelong social process through which individuals learn values, norms, and behaviors of their culture

Anomie

A state of normlessness and social instability resulting from a breakdown of societal standards

Major Depressive Disorder

A mood disorder characterized by persistent low mood, anhedonia, fatigue, and worthlessness lasting at least two weeks

Anhedonia

The complete loss of interest or pleasure in previously enjoyable activities

Bipolar I Disorder

A mood disorder defined by the occurrence of at least one manic episode