MCAT Individual Influences on Behavior
MCAT Individual Behavior covers how biological, psychological, and social factors shape behavior — from neurotransmitter action and brain lesions to personality theories and DSM-5 diagnostic categories. This is one of the broadest MCAT psychology topics, spanning hormones, nervous system organization, and major frameworks like psychoanalytic, humanistic, trait, and social-cognitive theories.
Some questions are standalone — name the defense mechanism, identify the neurotransmitter deficit, classify the disorder. More often, a clinical or experimental vignette describes a person's behavior and asks you to apply a specific theory or biological mechanism. MCAT behavioral science questions reward the student who can match theory to scenario, not just define terms.
The misconceptions that cost the most points here feel intuitive but are wrong: students think dopamine means happiness when it actually drives reward-seeking, treat the hippocampus as a memory storage site rather than a consolidation hub, and interpret heritability as an individual percentage rather than a measure of population variance. These three distinctions alone separate strong MCAT psych/soc scorers from average ones.
Nervous System Organization in Behavior
Predicting ANS physiological signatures — heart rate, pupils, GI, sweating — from a described behavioral state.
- Confuses somatic and autonomic targets — somatic is skeletal/voluntary only
- Assumes every organ has both sympathetic and parasympathetic innervation with opposing effects
Brain Regions and Their Behavioral Roles
Lesion-to-deficit mapping: frontal damage, Broca/Wernicke aphasias, HM amnesia, and what each brain method actually measures.
- Confuses hippocampus as the permanent storage site rather than the consolidation gateway for declarative memory
- Overgeneralizes amygdala function to all emotions rather than emphasizing its primary role in fear
Neurotransmitters in Behavior (DA, 5-HT, NE, GABA, Glu, ACh)
Linking DA, 5-HT, NE, GABA, Glu, and ACh to disorders, drugs, and the time course of behavioral effects.
- Conflates dopamine with happiness/pleasure rather than reward-seeking and motivation
- Reverses dopamine levels in Parkinson's disease vs schizophrenia
Hormones and Behavior
HPA and HPG axis feedback loops connect cortisol, oxytocin, and sex hormones to stress and social behavior.
- Treats cortisol as uniformly harmful rather than adaptive in acute stress and harmful only when chronic
- Confuses HPA axis feedback as positive rather than negative
Genes vs Environment; Twin and Adoption Studies
Twin and adoption study logic disentangles genetic from environmental contributions; heritability is a population statistic, not an individual one.
- Misapplies heritability as a per-individual genetic percentage rather than a population-level variance statistic
- Assumes 100% MZ concordance is expected for purely genetic traits, ignoring epigenetics and developmental noise
Psychoanalytic Theory of Personality (Freud)
Recognizing which defense mechanism — projection, displacement, sublimation, reaction formation — is illustrated in a passage scenario.
- Treats the superego as a conscious moral faculty rather than a largely unconscious internalized standard
- Confuses projection (attributing feelings to others) with displacement (redirecting feelings to a substitute target)
Humanistic Personality Theories (Maslow, Rogers)
Rogers' congruence and Maslow's hierarchy applied to therapy and motivation passages, with flexibility rather than rigid stage logic.
- Applies Maslow's hierarchy as a rigid gate rather than a flexible prioritization framework
- Confuses unconditional positive regard with approval of behavior rather than acceptance of the person
Trait Theories (Big Five, Allport, Cattell, Eysenck)
OCEAN dimensions and the person-situation debate — when stable traits predict behavior and when situational factors override them.
- Conflates Big Five neuroticism (emotional instability trait) with neurological disease
- Confuses a transient emotional state with a stable personality trait
Social-Cognitive Theories (Bandura, Locus of Control)
Bandura's reciprocal determinism and Rotter's locus of control predict achievement and health behavior in passage vignettes.
- Conflates self-efficacy (task-specific competence belief) with self-esteem (global self-worth)
- Treats Bandura's reciprocal determinism as unidirectional environment-to-behavior causation
Behaviorist Perspective on Personality
Personality as a history of conditioned responses — behaviorism rejects internal traits and predicts situational specificity, not cross-situational consistency.
- Attributes trait-based explanations to behaviorism — behaviorists explicitly reject internal traits as causes
- Assumes behaviorism predicts cross-situational consistency when it actually predicts situational specificity
Motivation Theories (Drive, Incentive, Maslow, Self-Determination)
Yerkes-Dodson's inverted-U, drive-reduction vs incentive theory, and self-determination theory appear in workplace and education vignettes.
- Confuses drive-reduction (internal push) with incentive theory (external pull)
- Treats Yerkes-Dodson as a linear positive relationship rather than an inverted-U
Major Psychological Disorders (DSM Categories)
Biopsychosocial model and DSM-5 categorical logic underlie symptom-to-diagnosis matching; overlapping criteria require full criteria review.
- Confuses DSM-5's categorical approach with a fully dimensional classification system
- Reduces mental illness etiology to biology alone, ignoring psychological and social contributors
Mood and Anxiety Disorders Overview
Distinguishing MDD, bipolar I/II, GAD, panic, OCD, and PTSD by core features and connecting each to its pharmacological target.
- Misclassifies OCD as an anxiety disorder rather than its own DSM-5 category
- Misclassifies PTSD as an anxiety disorder rather than a trauma/stressor-related disorder
Schizophrenia and Psychotic Disorders Overview
Positive vs negative symptoms map onto distinct dopamine pathways — mesolimbic excess drives hallucinations; mesocortical hypoactivity drives flat affect.
- Interprets 'positive symptoms' as favorable rather than as added abnormal experiences
- Applies uniform dopamine excess to all of schizophrenia rather than pathway-specific dysregulation
Personality Disorders (Clusters A, B, C)
Cluster A, B, and C patterns matched to vignettes; OCPD vs OCD and antisocial vs psychopathy are the highest-yield distinctions.
- Conflates OCPD (Cluster C personality disorder) with OCD (obsessive-compulsive disorder)
- Treats antisocial personality disorder and psychopathy as identical DSM-5 categories
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