Psychology cheat sheet

Resting potential ≈ −70 mV maintained by Na⁺/K⁺ ATPase (3 Na⁺ out, 2 K⁺ in); action potential fires when depolarization reaches threshold (~−55 mV), then Na⁺ channels inactivate and K⁺ efflux repolarizes (absolute refractory period).

Neurotransmitter quick map: dopamine = reward/motor (nigrostriatal loss → Parkinson's); serotonin = mood/sleep; norepinephrine = arousal; GABA = main inhibitory; glutamate = main excitatory; acetylcholine = muscle/NM junction and memory (basal forebrain).

Hindbrain: medulla (vital reflexes), pons (relay/sleep), cerebellum (coordination, motor learning). Midbrain: superior/inferior colliculi, substantia nigra. Forebrain: thalamus (sensory relay), hypothalamus (homeostasis, 4 Fs), basal ganglia (movement gating), limbic system (amygdala = fear, hippocampus = consolidation).

Cortical lobes: occipital (vision), temporal (audition, Wernicke's area), parietal (somatosensory, spatial), frontal (motor, Broca's area, executive). Broca's aphasia = nonfluent; Wernicke's = fluent but meaningless.

Hemispheric specialization: left = language, sequential/analytic; right = visuospatial, prosody, holistic. Split-brain (corpus callosum severed) shows left-hemisphere verbal report only for right visual field stimuli.

Sensation vs perception: absolute threshold (detected 50% of time), difference threshold/JND (Weber's law: ΔI/I = k), signal detection theory separates sensitivity (d′) from criterion (β).

Gestalt and depth cues: figure-ground, proximity, similarity, closure, continuity; binocular = retinal disparity, convergence; monocular = linear perspective, interposition, texture gradient, motion parallax, relative size.

Motivation: drive-reduction (homeostasis), arousal (Yerkes-Dodson inverted U - moderate arousal optimal), Maslow hierarchy, intrinsic vs extrinsic. Emotion theories: James-Lange (body first), Cannon-Bard (simultaneous), Schachter-Singer two-factor (arousal + cognitive label), Lazarus (appraisal first).

Classical conditioning: CS paired with UCS → CR; acquisition, extinction, spontaneous recovery, generalization, discrimination. Rescorla-Wagner: conditioning depends on CS's predictive value (contingency, not mere contiguity).

Operant conditioning: reinforcement increases behavior, punishment decreases it; positive = add stimulus, negative = remove. Schedules: fixed/variable ratio (based on responses) vs interval (based on time); variable schedules resist extinction best.

Memory systems: sensory (iconic ~250 ms, echoic ~3–4 s), working memory (Baddeley: phonological loop, visuospatial sketchpad, central executive, episodic buffer; capacity ~4 chunks), long-term (explicit = episodic/semantic; implicit = procedural, priming).

Encoding/retrieval: levels of processing (deep semantic > shallow), spacing effect, testing effect, encoding specificity and context-dependent memory; serial position curve = primacy (LTM) + recency (STM).

Forgetting: decay, interference (proactive = old disrupts new; retroactive = new disrupts old), retrieval failure, motivated forgetting. Ebbinghaus forgetting curve is steepest early.

Problem solving: algorithms vs heuristics (availability, representativeness, anchoring-adjustment); functional fixedness, mental set, confirmation bias; insight vs trial-and-error.

Language: phoneme → morpheme → syntax → semantics → pragmatics. Chomsky's LAD/universal grammar vs Skinner's operant account; critical period evidence from Genie and deaf late signers.

Intelligence: Spearman's g, Cattell-Horn-Carroll (fluid vs crystallized), Gardner's multiple intelligences, Sternberg's triarchic. IQ = (mental age/chronological age) × 100 for ratio; deviation IQ standardized M=100, SD=15.

Piaget stages: sensorimotor (0–2; object permanence, A-not-B), preoperational (2–7; egocentrism, conservation failure, symbolic play), concrete operational (7–11; conservation, reversibility), formal operational (11+; abstract/hypothetical reasoning).

Vygotsky: zone of proximal development, scaffolding, private speech internalized as thought; culture and social interaction drive cognitive development.

Attachment: Ainsworth Strange Situation - secure (~60–65%), avoidant, ambivalent/resistant, disorganized; Harlow's contact comfort over food; Bowlby's internal working models.

Erikson psychosocial stages (8): trust/mistrust, autonomy/shame, initiative/guilt, industry/inferiority, identity/role confusion (adolescence), intimacy/isolation, generativity/stagnation, integrity/despair.

Kohlberg moral development: preconventional (punishment/self-interest), conventional (approval/law and order), postconventional (social contract/universal principles); Gilligan critiques gender bias (ethic of care).

Physical development: cephalocaudal and proximodistal sequences; puberty onset earlier in girls (~10–11) than boys (~12); brain maturation: sensory/motor first, prefrontal cortex last (through mid-20s).

Aging: fluid intelligence declines earlier than crystallized; processing speed, working memory, and sensory acuity decline; wisdom/emotional regulation often stable or improve. Neurogenesis and cognitive reserve modulate decline.

Temperament: Thomas & Chess (easy, difficult, slow-to-warm-up); goodness of fit. Baumrind parenting: authoritative (high warmth + high control) best outcomes; authoritarian, permissive, uninvolved.

Attribution: internal vs external; fundamental attribution error (overweight dispositional for others), actor-observer bias, self-serving bias, just-world belief. Kelley's covariation: consensus, distinctiveness, consistency.

Attitudes and behavior: cognitive dissonance (Festinger) - inconsistency motivates attitude change; self-perception theory (Bem) - behavior informs attitude when internal cues are weak; elaboration likelihood model (central vs peripheral route).

Conformity and obedience: Asch line studies (~37% conformity with unanimous wrong majority); Milgram obedience (~65% to 450V); normative vs informational social influence.

Group processes: social facilitation (simple tasks), social loafing (diffusion of responsibility), deindividuation, group polarization, groupthink (Janis), risky shift; bystander effect (Darley & Latané - helping decreases with more witnesses).

Prejudice and stereotypes: in-group bias, out-group homogeneity, stereotype threat (Steele), contact hypothesis (Allport - equal status, common goals, cooperation, institutional support).

Persuasion: source credibility, attractiveness, message framing, fear appeals with efficacy; foot-in-the-door, door-in-the-face, low-ball techniques.

Relationships: mere exposure effect, similarity attraction, reciprocity of liking, passionate vs companionate love (Sternberg's triangular theory: intimacy, passion, commitment); equity theory.

Social cognition: schemas, priming, automatic vs controlled processing; implicit attitudes measured by IAT; self-fulfilling prophecy and Pygmalion effect.

Psychoanalytic: id (pleasure principle), ego (reality principle), superego (morality); defense mechanisms (repression, projection, displacement, reaction formation, sublimation); Freud's psychosexual stages (oral, anal, phallic, latency, genital).

Humanistic: Maslow hierarchy (physiological → safety → belonging → esteem → self-actualization); Rogers - unconditional positive regard, congruence, self-concept vs ideal self.

Trait models: Allport (cardinal, central, secondary), Eysenck (extraversion, neuroticism, psychoticism), Cattell 16PF, Big Five (OCEAN - openness, conscientiousness, extraversion, agreeableness, neuroticism); conscientiousness best predicts job performance.

Social-cognitive: Bandura's reciprocal determinism (behavior, cognition, environment), self-efficacy, locus of control (Rotter - internal vs external), Mischel's person-situation debate.

Biological/temperament: heritability of Big Five traits roughly 40–60% in twin studies; behavioral activation (BAS) vs inhibition (BIS) systems; Gray's reinforcement sensitivity theory.

Psychometrics: reliability (test-retest, internal consistency via Cronbach's α, inter-rater) vs validity (content, criterion, construct); reliability is necessary but not sufficient for validity; standard error of measurement = SD√(1−r).

Item analysis: difficulty index (proportion passing), discrimination index (item-total correlation); norm-referenced vs criterion-referenced interpretation; standardization and percentile ranks vs standard scores.

Projective tests (Rorschach, TAT) have low incremental validity; MMPI-2 and NEO-PI-R are objective inventories with established psychometrics; response sets (acquiescence, social desirability) threaten validity.

DSM-5-TR organizes disorders by descriptive criteria: symptom duration, impairment, and exclusion of substance/medical causes; it is categorical with dimensional specifiers; ICD-11 is the WHO alternative. Neither implies etiology.

Anxiety disorders: panic disorder (recurrent unexpected attacks + anticipatory fear), agoraphobia, social anxiety, GAD (≥6 months excessive worry), specific phobia; first-line treatment = CBT ± SSRIs.

Mood disorders: MDD requires ≥5 symptoms for ≥2 weeks including depressed mood or anhedonia; mania = elevated/irritable mood ≥1 week with ↑energy, ↓need for sleep; bipolar I vs II (hypomania).

Psychotic disorders: schizophrenia requires ≥2 core symptoms (delusions, hallucinations, disorganized speech/behavior, negative symptoms) for ≥6 months with ≥1 month active; positive vs negative symptoms; dopamine hypothesis.

Neurodevelopmental: ADHD (inattention and/or hyperactivity-impulsivity, onset before 12, ≥6 months, cross-setting), autism spectrum (social communication deficits + restricted/repetitive behavior), intellectual disability (IQ ~70 or below + adaptive deficits).

Trauma/stress: PTSD (intrusion, avoidance, negative cognitions/mood, hyperarousal ≥1 month after trauma), acute stress disorder (<1 month), adjustment disorder; complex trauma specifiers.

Etiology frameworks: diathesis-stress (vulnerability × stress), biopsychosocial model, gene-environment interaction; heritability estimates: schizophrenia ~80%, MDD ~30–40%, anxiety ~30–40%.

Personality disorders (DSM-5 clusters): A = odd/eccentric (paranoid, schizoid, schizotypal); B = dramatic/erratic (antisocial, borderline, histrionic, narcissistic); C = anxious/fearful (avoidant, dependent, OCPD).

Psychodynamic: free association, dream analysis, transference/countertransference, defense interpretation; short-term dynamic therapies target specific conflicts; evidence strongest for depression and some personality issues.

Behavioral: exposure and response prevention (OCD first-line), systematic desensitization (Wolpe), flooding, token economies, aversion therapy; based on classical/operant principles.

Cognitive-behavioral: Beck's cognitive triad and cognitive restructuring; Ellis's REBT (irrational beliefs); behavioral activation for depression; CBT has strong evidence for depression, anxiety, OCD, insomnia (CBT-I).

Humanistic/existential: Rogers' person-centered (unconditional positive regard, empathy, congruence); Gestalt (Perls - here-and-now, empty chair); existential therapy (meaning, death anxiety).

Psychopharmacology: SSRIs/SNRIs (depression, anxiety; onset 2–6 weeks; serotonin syndrome risk), benzodiazepines (short-term anxiety; dependence risk), lithium (bipolar; narrow therapeutic index, monitor levels), antipsychotics (D2 blockade; EPS, tardive dyskinesia, metabolic syndrome), stimulants (ADHD).

Evidence hierarchy: RCTs > quasi-experimental > cohort > case studies; empirically supported treatments (ESTs) vs evidence-based practice (APA: research + clinical expertise + patient values); common factors (alliance, empathy) explain substantial variance.

Prevention: universal (whole population), selective (at-risk groups), indicated (early symptoms); tertiary prevention = rehabilitation/reducing relapse; measurement-based care improves outcomes.

Ethics/legal: informed consent, confidentiality with mandated exceptions (danger to self/other, abuse, court order), Tarasoff duty to protect, HIPAA, scope of competence, teletherapy jurisdictional rules.

Design: true experiment = random assignment + manipulated IV + control; quasi-experiment lacks random assignment; correlational design cannot establish causation; confounding vs extraneous variables.

Validity types: internal (causal inference), external (generalizability), construct (measures the construct), statistical conclusion; threats include history, maturation, testing, instrumentation, regression to the mean, attrition, selection.

Sampling: probability (simple random, stratified, cluster, systematic) vs nonprobability (convenience, purposive, snowball); sampling error decreases with √n; power = 1 − β, typically ≥.80.

Descriptive stats: mean/median/mode (median robust to outliers), range/variance/SD, z-scores (M=0, SD=1), percentile rank; normal curve: ~68% within ±1 SD, ~95% within ±2 SD, ~99.7% within ±3 SD.

Inferential: t-tests (one-sample, independent, paired), ANOVA (F = between/within variance; factorial designs test main effects and interactions), chi-square (categorical association), correlation (Pearson r, range −1 to +1; r² = variance explained).

Regression: linear regression predicts continuous outcome; multiple regression controls covariates; assumptions = linearity, independence, homoscedasticity, normality of residuals; multicollinearity inflates standard errors.

Error types: Type I (false positive, α) vs Type II (false negative, β); p-value = probability of data given null, not probability null is true; effect size (Cohen's d, η²) separate from significance.

Ethics: IRB review, informed consent, minimal risk, deception permitted only with debriefing and justification, confidentiality/anonymity, vulnerable populations (children, prisoners, cognitively impaired), animal welfare (IACUC, 3Rs).

Structuralism (Wundt - first psychology lab 1879 Leipzig; Titchener - introspection of elements) vs functionalism (James - adaptive purpose, stream of consciousness); Gestalt (Wertheimer, Köhler, Koffka - wholes over parts).

Behaviorism: Watson's 1913 manifesto, Little Albert; Skinner's operant analysis and radical behaviorism; cognitive revolution (Miller, Neisser, Chomsky's critique of Skinner) restored mental processes.

Psychoanalytic lineage: Freud → neo-Freudians (Jung, Adler, Horney, Erikson); humanistic third force (Maslow, Rogers); contemporary CBT integrates behavioral and cognitive traditions.

Applied areas: I/O psychology (job analysis, selection validity, Herzberg two-factor, expectancy theory, organizational justice); health psychology (biopsychosocial, adherence, stress-illness pathways); forensic (competency vs insanity - Dusky/M'Naghten).

School/educational psychology: assessment, IEPs, RTI/MTSS tiers, learning disabilities identification (discrepancy vs response-to-intervention models).

Professional issues: APA Ethics Code (beneficence, fidelity, integrity, justice, respect); licensure and scope; continuing education; supervision; recordkeeping retention; competence boundaries.

Testing standards: Standards for Educational and Psychological Testing (AERA/APA/NCME) govern fairness, validity evidence, and test use; test security and appropriate norm groups.

History of measurement: Galton (individual differences), Binet-Simon (first practical intelligence test, 1905), Wechsler scales (deviation IQ), Terman's Stanford-Binet; Army Alpha/Beta shaped group testing.