Psychology & Neuroscience

Schools of Psychology

• Structuralism — Wilhelm Wundt founded the first psychology laboratory (Leipzig, 1879); aimed to identify basic elements of conscious experience through introspection. Edward Titchener brought the school to America.
• Edward Titchener — Wundt’s student; founded the American school of structuralism at Cornell; introduced the term “structuralism”; emphasized introspective analysis of mental contents into sensations, images, and affections.
• Functionalism — William James (Principles of Psychology, 1890); focused on the purpose of mental processes rather than their structure; influenced by Darwinian evolution. Opposed Wundt’s atomism.
• Psychoanalysis — Sigmund Freud proposed that unconscious drives (especially sexual and aggressive) shape behavior; emphasized the id (pleasure principle), ego (reality principle), and superego (moral conscience). Defense mechanisms include repression, projection, rationalization, and reaction formation.
• Freudian psychosexual stages — oral, anal, phallic (Oedipus/Electra complex), latency, genital. Fixation at any stage was said to produce characteristic adult traits.
• Neo-Freudians — Carl Jung (collective unconscious, archetypes, introversion/extraversion), Alfred Adler (inferiority complex, birth order), Karen Horney (basic anxiety, cultural factors in neurosis), Erik Erikson (psychosocial development), Erich Fromm (see below).
• Behaviorism — argued psychology should study only observable behavior; rejected introspection. John B. Watson (“Psychology as the Behaviorist Views It,” 1913). B.F. Skinner extended behaviorism through operant conditioning.
• Humanistic psychology — Carl Rogers (person-centered therapy, unconditional positive regard) and Abraham Maslow (hierarchy of needs, self-actualization); emphasized conscious experience, free will, and human potential. Rose partly in reaction to behaviorism and psychoanalysis.
• Cognitive revolution — 1950s–1960s shift toward studying mental processes (perception, memory, language, reasoning) as information processing. Key figures: Ulric Neisser (Cognitive Psychology, 1967), George Miller (“The Magical Number Seven,” 1956), Noam Chomsky (critique of Skinner’s language account).
• Gestalt psychology — Max Wertheimer, Wolfgang Köhler, Kurt Koffka; “the whole is greater than the sum of its parts”; principles of perceptual organization: proximity, similarity, closure, continuity, figure-ground.
• Max Wertheimer — co-founder of Gestalt psychology; the phi phenomenon (apparent motion from two alternating stationary lights) was his paradigm case that perception cannot be reduced to individual elements.
• Wolfgang Köhler — Gestalt co-founder; studied insight learning in chimpanzees on Tenerife; argued for isomorphism between brain fields and perceived forms; authored The Mentality of Apes (1917).
• Kurt Koffka — Gestalt co-founder; brought Gestalt ideas to American psychology via Principles of Gestalt Psychology (1935).
• Hermann Ebbinghaus — first to study memory experimentally using nonsense syllables; described the forgetting curve (rapid initial loss, then leveling off) and the spacing effect (distributed practice beats massed practice); used himself as sole subject.
• Evolutionary psychology — applies Darwinian principles to psychological traits; argues many cognitive and social tendencies are adaptations. Associated with David Buss, Leda Cosmides, John Tooby.

Neuroscience Basics

The Neuron

• Neuron structure — cell body (soma), dendrites (receive signals), axon (transmits signals), myelin sheath (speeds conduction), terminal buttons (release neurotransmitters). Schwann cells form myelin in the peripheral nervous system; oligodendrocytes in the central nervous system.
• Action potential — an all-or-nothing electrical impulse generated when the membrane potential crosses threshold (~−55 mV). Depolarization (Na+ influx) followed by repolarization (K+ efflux); the brief refractory period prevents backward transmission.
• Resting potential — approximately −70 mV maintained by the Na+/K+ pump (3 Na+ out, 2 K+ in per cycle).
• Synapse — the junction between two neurons. Neurotransmitters are released from presynaptic vesicles into the synaptic cleft and bind postsynaptic receptors. Excitatory postsynaptic potentials (EPSPs) depolarize; inhibitory postsynaptic potentials (IPSPs) hyperpolarize.
• Reuptake and degradation — neurotransmitters are cleared by reuptake transporters (target of SSRIs, cocaine, amphetamines) or enzymatic breakdown (e.g., acetylcholinesterase degrades acetylcholine; MAO degrades monoamines).

Key Neurotransmitters

• Dopamine — reward, motivation, motor control; implicated in schizophrenia (excess) and Parkinson’s disease (deficit in substantia nigra). Mesolimbic pathway: reward; mesocortical: cognition; nigrostriatal: movement.
• Serotonin (5-HT) — mood, sleep, appetite; most neurons originate in the raphe nuclei. Depleted in depression; SSRIs block reuptake.
• Norepinephrine (noradrenaline) — arousal, attention, fight-or-flight; locus coeruleus is the primary source.
• Acetylcholine (ACh) — muscle contraction (neuromuscular junction), memory, autonomic function; loss of ACh neurons in the basal forebrain is associated with Alzheimer’s disease.
• GABA — the main inhibitory neurotransmitter in the brain; benzodiazepines and alcohol enhance GABA-A receptor activity.
• Glutamate — the main excitatory neurotransmitter; NMDA receptors are key to synaptic plasticity and learning. Excessive glutamate leads to excitotoxicity.
• Endorphins — endogenous opioids released during exercise and stress; bind opioid receptors and reduce pain.

Brain Anatomy

• Cerebral cortex — the outermost layer of the cerebrum; folded into gyri (ridges) and sulci (grooves). Divided into left and right hemispheres connected by the corpus callosum.
• Frontal lobe — executive function, planning, voluntary movement (primary motor cortex), and Broca’s area (speech production, left hemisphere). The prefrontal cortex is central to decision-making and impulse control.
• Parietal lobe — somatosensory processing (primary somatosensory cortex), spatial awareness, and integration of sensory information.
• Temporal lobe — auditory processing, language comprehension (Wernicke’s area, left hemisphere), and memory (hippocampus sits beneath the temporal lobe).
• Occipital lobe — primary visual cortex and visual processing.
• Limbic system — emotional and memory circuits: amygdala (fear, emotional memory), hippocampus (encoding new declarative memories), hypothalamus (homeostasis, hormonal control of pituitary), cingulate cortex.
• Basal ganglia — clusters of nuclei (caudate, putamen, globus pallidus) involved in motor control and habit learning; disrupted in Parkinson’s and Huntington’s disease.
• Thalamus — the brain’s relay station; routes sensory information to appropriate cortical areas (except olfaction).
• Cerebellum — coordination, fine motor control, motor learning, and some cognitive functions.
• Brainstem — midbrain, pons, and medulla oblongata; controls vital functions (breathing, heart rate, arousal) and houses reticular activating system.
• Broca’s area vs. Wernicke’s area — Broca’s area (inferior frontal gyrus, left): speech production; damage causes Broca’s (expressive) aphasia — halting, effortful speech. Wernicke’s area (posterior superior temporal gyrus, left): language comprehension; damage causes Wernicke’s (receptive) aphasia — fluent but nonsensical speech.

Neuroplasticity and Learning

• Synaptic plasticity — synapses strengthen or weaken with use. Long-term potentiation (LTP) — persistent strengthening from repeated stimulation; the leading cellular model of memory.
• Long-term depression (LTD) — the counterpart to LTP; synapses weaken with low-frequency stimulation; critical for motor learning in the cerebellum and for clearing outdated synaptic traces.
• Hebb’s rule — “neurons that fire together wire together”; repeated co-activation strengthens synaptic connections.
• Neurogenesis — new neurons are generated in the adult hippocampus (dentate gyrus) and olfactory bulb; role in learning and mood regulation is an active area of research.
• Cortical homunculus (Penfield) — Wilder Penfield’s map of the sensory and motor cortices showing the distorted “little man” whose body regions are represented proportionally to their innervation density, not their physical size; hands and lips are disproportionately large.
• Mirror neurons — neurons in primate premotor cortex (area F5) that fire both when an animal performs an action and when it observes the same action; discovered in macaques by Rizzolatti and colleagues; proposed role in imitation and empathy in humans, though the human evidence is more indirect and contested.
• Corpus callosum — the large white-matter bundle connecting the two cerebral hemispheres; severed in split-brain surgeries to treat intractable epilepsy; its absence (callosal agenesis) produces surprisingly subtle deficits in some cases.
• Reticular activating system (RAS) — network in the brainstem reticular formation projecting to the thalamus and cortex; controls arousal, alertness, and sleep-wake transitions; general anesthetics partly act here.
• fMRI, EEG, and PET — three major brain imaging methods: fMRI measures BOLD (blood-oxygen-level-dependent) signal as a proxy for neural activity, high spatial resolution; EEG records scalp electrical potentials, high temporal resolution but poor spatial resolution; PET uses radioactive tracers to measure blood flow or neurotransmitter binding.

Cognition

Memory

• Sensory memory — very brief retention of sensory information: iconic memory (visual, ~0.5 s; studied by Sperling) and echoic memory (auditory, ~3–4 s).
• Short-term / working memory — limited capacity (~7 ± 2 items, per Miller 1956); maintained by active rehearsal. Working memory model (Baddeley and Hitch): phonological loop, visuospatial sketchpad, central executive, and episodic buffer.
• Long-term memory — potentially unlimited, long-lasting storage. Divided into explicit (declarative) memory: episodic (personal events) and semantic (facts, concepts). Implicit (nondeclarative) memory: procedural (skills, habits), priming, and conditioning.
• H.M. (Henry Molaison) — patient whose bilateral hippocampal removal (1953) by surgeon William Beecher Scoville eliminated new episodic memory formation (anterograde amnesia) while sparing older memories and procedural learning; the most studied neurological case in history; studied for decades by Brenda Milner.
• Patient K.C. (Kent Cochrane) — amnesic patient with hippocampal damage who retained semantic memory but had no episodic memory whatsoever (could not mentally time-travel to past or future events); helped distinguish episodic from semantic memory systems.
• Clive Wearing — British musician with severe anterograde and retrograde amnesia from herpes encephalitis; retains procedural memory for piano playing and conducting, demonstrating the hippocampus-independent nature of procedural memory.
• Encoding specificity — memories are best retrieved in conditions matching encoding (Tulving and Thomson, 1973). State-dependent memory: recall is better in the same physical/emotional state as encoding.
• Forgetting — Ebbinghaus forgetting curve (1885): memory declines rapidly then levels off; rehearsal and the spacing effect improve retention. Interference: proactive (old interferes with new) and retroactive (new interferes with old).
• Elizabeth Loftus — demonstrated that memory is reconstructive, not reproductive; misinformation effect; false memories can be implanted; landmark work on eyewitness testimony reliability. Her “lost in the mall” study showed that ~25% of participants could be induced to “remember” a false childhood event.
• Serial position effect — items at the beginning (primacy effect) and end (recency effect) of a list are recalled better than middle items; primacy attributed to long-term storage via rehearsal; recency attributed to short-term memory; originally described by Ebbinghaus and formalized by Murdock (1962).

Attention and Perception

• Selective attention — Cherry’s cocktail party effect: we can focus on one auditory stream while monitoring others for significance (e.g., one’s own name breaks through). Dichotic listening experiments (Colin Cherry, 1953) established this; subjects shadowed one ear and could report little from the unattended channel except physical features.
• McGurk effect — audiovisual speech illusion (McGurk and MacDonald, 1976): when the sound “ba” is dubbed onto a video of lips saying “ga,” most listeners perceive “da”; demonstrates that speech perception is multimodal, not purely auditory.
• Stroop effect — naming the ink color of a color word is slower when word and color conflict (e.g., the word RED printed in blue ink); demonstrates automaticity of reading and attentional interference; classic paradigm in cognitive psychology since John Ridley Stroop (1935).
• Inattentional blindness — failure to notice unexpected stimuli when attention is engaged elsewhere; classic demonstration: Simons and Chabris gorilla experiment (1999).
• Change blindness — failure to detect changes in a visual scene across interruptions.
• Signal detection theory — distinguishes sensitivity (d’) from response criterion (β); separates perceptual sensitivity from decision bias. Developed by Green and Swets.
• Gestalt perception principles — proximity, similarity, closure, continuity, figure-ground, common fate govern how elements are grouped into percepts.
• Weber’s law — the just-noticeable difference (JND) is a constant proportion of the original stimulus intensity; formalized into Fechner’s law and later Stevens’ power law.

Cognitive Biases and Judgment

• Kahneman and Tversky — developed prospect theory (losses loom larger than equivalent gains; Kahneman 2002 Nobel Prize in Economics) and catalogued systematic heuristics and biases.
• Availability heuristic — frequency or probability judged by ease of examples coming to mind; leads to overestimating vivid or recent events.
• Representativeness heuristic — probability judged by resemblance to a prototype; produces base-rate neglect and the conjunction fallacy (Linda problem).
• Anchoring — initial values disproportionately influence subsequent estimates.
• Confirmation bias — tendency to seek, interpret, and remember information that confirms existing beliefs.
• Wason selection task — Peter Wason (1966): given four cards showing E, K, 4, 7 and the rule “if a card has a vowel on one side, it has an even number on the other,” most people correctly choose E but incorrectly choose 4 rather than 7; reveals confirmation bias and difficulty with falsification logic; performance improves dramatically when framed in social/deontic terms (Cosmides’s cheater-detection results).
• Dunning-Kruger effect — low-ability individuals tend to overestimate their competence; highly skilled individuals may underestimate relative to peers. Subsequent replication debates have refined (but not eliminated) the core finding.
• Cognitive dissonance (Festinger, 1957) — discomfort from holding contradictory cognitions; motivates attitude or behavior change. Classic study: Festinger and Carlsmith paid participants $1 or $20 to lie; $1 group changed attitudes more.
• System 1 and System 2 (Kahneman) — System 1: fast, automatic, intuitive, heuristic-driven; System 2: slow, deliberate, effortful, rule-based; popularized in Thinking, Fast and Slow (2011); the framework synthesizes decades of heuristics-and-biases research.
• Prospect theory — Kahneman and Tversky (1979): people evaluate outcomes as gains/losses relative to a reference point; loss aversion (losses ~2× more impactful than equivalent gains); the value function is S-shaped, concave for gains, convex for losses; probability weighting overweights small probabilities.
• Fundamental attribution error (FAE) — (Lee Ross, 1977) tendency to overattribute others’ behavior to internal dispositions and underweight situational factors; also called correspondence bias; the classic demonstration used essay studies where subjects attributed pro-Castro attitudes even when told the author was assigned the topic.
• Hawthorne effect — productivity increased among workers at the Hawthorne plant apparently because they were being observed, not due to specific environmental changes; the term now broadly means behavior changes due to awareness of being studied. The original studies’ methodology has been substantially critiqued.
• Placebo effect — improvement in a patient’s condition attributable to the belief that an inert treatment is effective, rather than to any pharmacological action; placebo responses can produce measurable physiological changes (endorphin release, altered immune markers); nocebo effect: negative expectations worsen outcomes; open-label placebos (patients told the pill is inert) can still produce benefits; central to the design of randomized controlled trials, which require placebo controls to isolate true treatment effects.
• Instinct — in ethology, a fixed, innate, species-typical behavior pattern triggered by a specific stimulus (a sign stimulus or releaser); associated with Konrad Lorenz and Nikolaas Tinbergen, who described fixed action patterns (FAPs): stereotyped behavioral sequences that once initiated run to completion; imprinting (Lorenz) is a critical-period form of learning resembling instinct; in psychology, the concept was central to Freud (Eros and Thanatos) but largely replaced in behavioral science by more fine-grained accounts of motivation and learning.
• Halo effect — tendency to let one positive (or negative) trait color overall judgments of a person; Edward Thorndike coined the term in 1920; teachers’ physical attractiveness biases academic assessments of students.
• Groupthink (Irving Janis, 1972) — highly cohesive groups suppress dissent and critical evaluation in favor of consensus; illustrated by case studies of Bay of Pigs, Challenger disaster; symptoms include illusion of invulnerability, collective rationalization, and self-censorship.
• Bystander effect (Latané and Darley, 1968) — in emergencies, the presence of other people reduces the probability that any individual will intervene; two mechanisms: diffusion of responsibility and pluralistic ignorance; motivated by the 1964 murder of Kitty Genovese, though the original newspaper claim that 38 witnesses “did nothing” has been revised by historical scholarship.

Language

• Chomsky’s universal grammar — argued that children’s rapid, error-constrained language acquisition implies an innate language acquisition device (LAD); the poverty of the stimulus argument. Opposed Skinner’s operant account of language.
• Linguistic relativity (Sapir-Whorf hypothesis) — strong version (language determines thought) is largely rejected; weak version (language influences certain cognitive processes) has empirical support, especially in color perception and spatial reasoning. Named for linguist Edward Sapir and his student Benjamin Lee Whorf.
• Critical period — language acquisition is most efficient before puberty; evidence from feral children (e.g., “Genie”) and second-language learning.

Learning and Conditioning

• Classical (Pavlovian) conditioning — Ivan Pavlov discovered conditioned reflexes in dogs: neutral stimulus (bell) paired with unconditioned stimulus (food) eventually elicits conditioned response (salivation) alone. Key terms: acquisition, extinction, spontaneous recovery, generalization, discrimination.
• Higher-order conditioning — a conditioned stimulus is used to condition a new neutral stimulus, without direct pairing with the unconditioned stimulus; demonstrates that conditioning can chain beyond first-order associations.
• Operant (instrumental) conditioning — B.F. Skinner; behavior is shaped by its consequences. Positive reinforcement (add reward), negative reinforcement (remove aversive), positive punishment (add aversive), negative punishment (remove reward). Schedules of reinforcement: fixed-ratio, variable-ratio (most resistant to extinction), fixed-interval, variable-interval.
• Shaping — reinforcing successive approximations toward a target behavior (Skinner).
• Observational (social) learning — Albert Bandura’s Bobo doll experiment (1961): children who observed an adult model behaving aggressively toward a Bobo doll subsequently imitated that aggression; demonstrated learning without direct reinforcement. Foundation of social learning theory.
• Latent learning — Edward Tolman showed that rats learn maze layouts without reinforcement; proposed cognitive maps.
• Insight learning — Wolfgang Köhler showed chimpanzees (Sultan) solved novel problems (stacking boxes, joining sticks) through apparent sudden reorganization rather than trial and error.
• Thorndike’s law of effect — Edward Thorndike (1898): responses followed by satisfying consequences are more likely to recur; responses followed by discomfort are less likely; derived from puzzle box experiments in which cats learned to escape by trial and error; foundational to operant conditioning.
• Yerkes-Dodson law — (Robert Yerkes and John Dodson, 1908) performance is an inverted-U function of arousal: too little or too much arousal impairs performance; optimal arousal is lower for complex tasks than for simple tasks.
• Learned helplessness — (Martin Seligman and Steven Maier, 1967) dogs exposed to inescapable shocks later failed to escape shocks when escape was possible; proposed as an animal model of depression; Seligman later developed the cognitive reformulation (attributional style) and, still later, positive psychology.
• Self-efficacy (Bandura, 1977) — an individual’s belief in their capacity to execute specific behaviors to produce given outcomes; distinct from self-esteem; predicts motivation, effort, and persistence; central to social cognitive theory.

Development

Cognitive Development (Piaget)

• Jean Piaget — proposed four stages of cognitive development based on schemas, assimilation, and accommodation.
• Sensorimotor stage (0–2 years): knowledge through action; object permanence develops (~8 months).
• Preoperational stage (2–7 years): symbolic/language use; egocentrism (three-mountain task); animism; lacks conservation.
• Concrete operational stage (7–11 years): logical thinking about concrete objects; conservation mastered; seriation and classification.
• Formal operational stage (12+): abstract and hypothetical reasoning.
• Criticisms of Piaget — underestimated children’s abilities; stages less discrete than proposed; cultural and social factors underweighted.
• Object permanence — Piaget’s term for the understanding that objects continue to exist when out of sight; develops around 8 months in the sensorimotor stage; its apparent absence earlier may partly reflect motor limitations, as shown by Baillargeon’s violation-of-expectation studies.
• Conservation (Piaget) — understanding that quantity is unchanged by changes in shape or arrangement; mastered in concrete operations; classic demonstrations use clay balls and liquid in containers; preoperational children “fail” conservation tasks.
• Theory of mind — understanding that others have beliefs, desires, and intentions different from one’s own; typically assessed by the false-belief task (Wimmer and Perner, 1983); develops around age 4; delayed in autism spectrum disorder; linked to prefrontal and temporoparietal junction function.
• Vygotsky — emphasized social and cultural context; zone of proximal development (ZPD): gap between what a child can do alone vs. with guidance; scaffolding.

Psychosocial Development (Erikson)

• Erik Erikson’s eight stages — each stage presents a conflict whose resolution shapes personality. Key stages: Trust vs. Mistrust (infancy), Autonomy vs. Shame/Doubt (toddler), Initiative vs. Guilt (preschool), Industry vs. Inferiority (school age), Identity vs. Role Confusion (adolescence), Intimacy vs. Isolation (young adult), Generativity vs. Stagnation (middle adult), Ego Integrity vs. Despair (late adult).

Attachment (Bowlby and Ainsworth)

• John Bowlby — evolutionary-ethological theory of attachment; infants have an innate need for proximity to a caregiver; internal working models guide future relationships.
• Mary Ainsworth — Strange Situation procedure identified four attachment patterns: secure (explores freely, distressed by separation, reassured on return), anxious-avoidant (indifferent to caregiver, avoids reunion), anxious-ambivalent/resistant (clingy, not soothed on return), and disorganized (inconsistent; associated with maltreatment).
• Harlow’s monkeys — infant rhesus monkeys preferred a cloth surrogate “mother” over a wire surrogate that provided food; demonstrated importance of contact comfort over mere feeding in attachment.

Moral Development

• Kohlberg’s stages — preconventional (obedience/self-interest), conventional (conformity/law and order), postconventional (social contract/universal principles); used Heinz dilemma. Carol Gilligan argued the model is gender-biased, undervaluing an “ethic of care.”
• Heinz dilemma — Kohlberg’s vignette in which a man must decide whether to steal a drug to save his dying wife; used to classify participants’ stage of moral reasoning by the justifications they give, not the yes/no answer.
• Carol Gilligan — In a Different Voice (1982); critiqued Kohlberg for using male samples; proposed that women more often reason through an ethic of care (relationships, context) vs. the ethic of justice (rules, rights) Kohlberg emphasized.

Famous Experiments

• Pavlov’s dogs — classic conditioning of salivation to a bell; established the foundations of behavioral psychology. Ivan Pavlov (1890s–1900s).
• Sherif’s Robbers Cave experiment (1954) — Muzafer Sherif divided boys at a summer camp into two groups (Rattlers and Eagles), fostered intergroup conflict through competition, then reduced hostility via superordinate goals requiring cooperation; demonstrated realistic conflict theory and the contact hypothesis requires cooperative interdependence.
• Watson and Rayner — Little Albert (1920) — conditioned fear of a white rat in an infant by pairing it with a loud noise; demonstrated classical conditioning of emotional responses in humans. The child was never deconditioned; the study is widely regarded as profoundly unethical. The subject’s identity is disputed in the literature.
• Skinner box — an operant conditioning chamber used to study how schedules of reinforcement shape behavior in animals (rats, pigeons).
• Milgram obedience studies (1963) — participants instructed by an authority figure to administer increasingly severe electric shocks to a “learner” (confederate); the originally reported 65% compliance to the maximum 450-V level has been debated by Gina Perry and others on grounds of participant debriefing and data fidelity. The studies remain a landmark in social psychology but are cited cautiously. Were deeply controversial ethically and led to major reforms in research ethics standards.
• Asch conformity experiments (1951–1956) — participants gave clearly wrong answers on line-length judgments when confederates unanimously gave the wrong answer; ~75% conformed at least once; demonstrated power of social pressure on perception and judgment.
• Stanford Prison Experiment (Zimbardo, 1971) — college students assigned as “guards” or “prisoners” in a simulated prison; the experiment was halted after 6 days (not 14 as sometimes reported). Zimbardo served as “prison superintendent,” creating demand characteristics; subsequent critiques by Blum (2018) and primary-source analysis have substantially undermined its conclusions. Its influence on social psychology and ethics policy has been large, but replication is not possible and the original claims are contested.
• Bobo doll study (Bandura, 1961) — see Observational Learning above.
• Festinger and Carlsmith cognitive dissonance (1959) — see Cognitive Biases above.
• Rosenhan experiment (1973) — pseudopatients gained psychiatric admission by claiming hallucinations, then behaved normally; all were admitted and labeled schizophrenic; raised questions about diagnostic validity. A planned follow-up described under-detection by a hospital that was told to expect pseudopatients. Replication and methodology have been critiqued. verify: Susannah Cahalan’s 2019 investigation The Great Pretender raised serious doubts about Rosenhan’s data and the identity of his pseudopatients.
• Jane Elliott’s Blue Eyes/Brown Eyes experiment (1968) — teacher divided third graders by eye color and told one group they were superior; the “inferior” group’s performance and demeanor declined within a day; demonstrated rapid internalization of social hierarchy and prejudice; originally conducted the day after Martin Luther King Jr.’s assassination.
• Split-brain studies (Sperry and Gazzaniga, 1960s) — patients with severed corpus callosum showed that left and right hemispheres can operate independently; left hemisphere handles language and analytical tasks; right handles spatial/holistic processing. Roger Sperry received the 1981 Nobel Prize in Physiology or Medicine for this work.
• Marshmallow test (Mischel, 1970s) — delayed gratification in children (preschoolers) predicted later life outcomes (SAT scores, BMI); widely cited. A 2018 replication (Watts, Duncan, Quan) found effects largely disappeared after controlling for family socioeconomic background, substantially narrowing the original interpretation.

Brain Disorders and Clinical Neuroscience

• Phineas Gage (1848) — railroad worker survived a tamping iron through his frontal lobes; reported personality changes (impulsive, profane); a seminal case linking frontal lobes to personality and social behavior. Some specific behavioral claims in popular accounts exceed what the primary records document.
• Paul Broca’s patient Tan — Louis Victor Leborgne, who could only utter the syllable “tan”; autopsy revealed a left frontal lesion; Broca presented the case in 1861 as evidence for cerebral localization of speech; the lesion site is now called Broca’s area (Brodmann area 44/45).
• Urbach-Wiethe disease — a rare condition causing bilateral amygdala calcification; patient S.M. (studied by Ralph Adolphs and Antonio Damasio) showed no fear response to snakes, spiders, or threatening situations; foundational evidence for the amygdala’s role in fear processing.
• Broca’s and Wernicke’s aphasias — see Brain Anatomy section.
• Anterograde vs. retrograde amnesia — inability to form new memories vs. loss of memories formed before the injury. H.M.’s case established hippocampal role in anterograde declarative memory.
• Prosopagnosia — inability to recognize faces despite intact vision and general object recognition; associated with fusiform face area damage.
• Hemispatial neglect — failure to attend to stimuli on the side contralateral to a parietal lesion, typically the right parietal lobe causes left neglect.
• Parkinson’s disease — loss of dopaminergic neurons in the substantia nigra; symptoms: resting tremor, bradykinesia, rigidity, postural instability. Treated with levodopa (L-DOPA).
• Alzheimer’s disease — most common dementia; hallmark pathology: amyloid-beta plaques and neurofibrillary tangles (tau protein); early loss of cholinergic neurons in basal forebrain (nucleus basalis of Meynert).
• Capgras delusion — belief that a familiar person has been replaced by an identical impostor; associated with right hemisphere lesions disrupting the link between face recognition and emotional familiarity; explained by Ramachandran as disconnection between fusiform face area and amygdala.
• Phantom limb — sensation that an amputated limb is still present; Vilayanur Ramachandran used a mirror box to treat phantom limb pain by creating the visual illusion of the missing limb; evidence for cortical remapping after amputation.
• Huntington’s disease — autosomal dominant neurodegenerative disorder caused by CAG trinucleotide repeat expansion in the HTT gene on chromosome 4; progressive destruction of striatum (caudate and putamen); symptoms: chorea, psychiatric changes, dementia; onset typically in middle age.
• Antipsychotics (neuroleptics) — first-generation (typical) antipsychotics (e.g., haloperidol, chlorpromazine) block D2 dopamine receptors; second-generation (atypical) antipsychotics (e.g., clozapine, risperidone) also block serotonin (5-HT2A) receptors, with lower extrapyramidal side-effect risk.
• Somatic marker hypothesis (Antonio Damasio) — emotions and bodily signals guide decision-making; patients with ventromedial prefrontal cortex damage show impaired real-life decisions despite intact reasoning (Iowa Gambling Task); Descartes’ Error (1994).
• Split-brain lateralization details — left hemisphere: language, serial/analytical processing, right visual field; right hemisphere: spatial processing, face recognition, holistic processing, left visual field; isolated right hemisphere can understand simple language but cannot speak; Gazzaniga extended Sperry’s work to human subjects and coined the “left brain interpreter” concept.

Psychological Disorders and the DSM

• DSM — the Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association. DSM-5 (2013) replaced DSM-IV’s multiaxial system; DSM-5-TR published 2022.
• Diathesis-stress model — psychological disorders result from the interaction of a biological or psychological predisposition (diathesis) with environmental stressors; explains why not everyone with a genetic risk factor develops a disorder.
• Big Five (OCEAN) — the dominant dimensional model of personality: Openness to experience, Conscientiousness, Extraversion, Agreeableness, Neuroticism; derived from lexical hypothesis and factor analysis; more empirically supported than type-based models (MBTI).
• MMPI (Minnesota Multiphasic Personality Inventory) — the most widely used clinical personality assessment; developed by Hathaway and McKinley (1940s); empirically keyed (scales built from items distinguishing criterion groups from normals); current version is MMPI-3; includes validity scales to detect faking.
• Rorschach inkblot test — projective personality test developed by Hermann Rorschach (1921); respondents describe ambiguous inkblots; responses coded for content, location, and determinants; psychometric validity debated; the Exner Comprehensive System attempted standardization.
• Thematic Apperception Test (TAT) — Henry Murray and Christiana Morgan (1935); projective test using ambiguous pictures; subjects narrate stories; used to assess implicit motives (achievement, power, affiliation); validity for clinical diagnosis is contested.
• Major depressive disorder — depressed mood or anhedonia most of the day for ≥2 weeks plus additional symptoms (sleep, appetite, concentration changes, worthlessness, suicidal ideation).
• Bipolar disorder — cycles of depression and mania (Bipolar I: full manic episodes; Bipolar II: hypomania).
• Schizophrenia — positive symptoms (hallucinations, delusions, disorganized thought), negative symptoms (flat affect, alogia, avolition); dopamine hyperactivity hypothesis; typically emerges in late adolescence/early adulthood.
• Anxiety disorders — generalized anxiety disorder (GAD), panic disorder, specific phobias, social anxiety disorder, agoraphobia.
• Obsessive-compulsive disorder (OCD) — moved to its own chapter in DSM-5; intrusive obsessions drive compulsive behaviors.
• PTSD — trauma-related disorder; re-experiencing, avoidance, negative cognitions/mood, hyperarousal.
• Autism spectrum disorder (ASD) — persistent deficits in social communication; restricted, repetitive behaviors; spectrum reflects wide variation in support needs. DSM-5 collapsed previous subtypes (Asperger’s, PDD-NOS) into a single spectrum.
• ADHD — inattention and/or hyperactivity-impulsivity; must be present before age 12 in multiple settings.
• Personality disorders — enduring, inflexible patterns across DSM-5 Cluster A (odd/eccentric: paranoid, schizoid, schizotypal), Cluster B (dramatic: antisocial, borderline, histrionic, narcissistic), Cluster C (anxious: avoidant, dependent, obsessive-compulsive).
• Therapies — CBT (cognitive-behavioral therapy): challenges distorted thoughts and behaviors; gold standard for many disorders. Psychodynamic therapy: insight into unconscious conflicts. DBT (dialectical behavior therapy): Marsha Linehan; adapted CBT for borderline PD; skills: mindfulness, distress tolerance, emotion regulation, interpersonal effectiveness. Exposure therapy: systematic desensitization for phobias (Wolpe). EMDR: evidence-based for PTSD.

Intelligence and Measurement

• Binet and Simon (1905) — developed the first practical intelligence test to identify students needing academic support in France; introduced mental age.
• IQ — intelligence quotient. Stern formula: (mental age / chronological age) × 100. Modern IQ tests (Wechsler) use deviation IQ (mean 100, SD 15).
• Gardner’s multiple intelligences — proposed 8+ relatively independent intelligences (linguistic, logical-mathematical, spatial, musical, bodily-kinesthetic, interpersonal, intrapersonal, naturalist). Not widely accepted in psychometrics.
• Sternberg’s triarchic theory — analytic, creative, and practical intelligence.
• Flynn effect — IQ scores have risen substantially across generations in many countries (James Flynn); causes debated (nutrition, education, abstract thinking demands).
• Heritability of IQ — twin and adoption studies suggest heritability of ~50–80% in adults; gene-environment interplay is significant and heritability estimates do not apply to group differences.
• Stanford-Binet intelligence scale — first American IQ test, adapted by Lewis Terman at Stanford from Binet-Simon (1916); introduced the ratio IQ formula; current edition (SB5) uses deviation IQ like the Wechsler scales.
• Wechsler scales — David Wechsler developed the WAIS (adults), WISC (children), and WPPSI (preschool); yield a Full-Scale IQ plus index scores (verbal comprehension, perceptual reasoning, working memory, processing speed); use deviation IQ (mean 100, SD 15).
• Stereotype threat (Claude Steele and Joshua Aronson, 1995) — awareness of a negative stereotype about one’s group depresses performance on relevant tests.
• Spearman’s g — general intelligence factor extracted by factor analysis; positive manifold: all cognitive tests tend to correlate; Cattell further split g into fluid intelligence (gf: novel reasoning, peaks in young adulthood) and crystallized intelligence (gc: accumulated knowledge and skills, relatively stable with age); the Gf-Gc model was extended by John Horn and John Carroll into the CHC theory.

Key Figures Summary

• Wilhelm Wundt — founded experimental psychology (1879 Leipzig lab); structuralism; introspection; also developed Völkerpsychologie (cultural/folk psychology) in later career.
• Sigmund Freud — psychoanalysis; unconscious; id/ego/superego; psychosexual stages.
• Ivan Pavlov — classical conditioning; Nobel Prize 1904 (for digestion research, not conditioning).
• John B. Watson — behaviorism manifesto; Little Albert study; “father of behaviorism.”
• B.F. Skinner — operant conditioning; Skinner box; Verbal Behavior (1957); radical behaviorism.
• Abraham Maslow — hierarchy of needs; self-actualization; humanistic psychology.
• Lev Vygotsky — zone of proximal development; social/cultural learning.
• Erik Erikson — eight psychosocial stages across the lifespan.
• Albert Bandura — social learning theory; Bobo doll; self-efficacy concept.
• Stanley Milgram — obedience to authority experiments; ethical controversy.
• Philip Zimbardo — Stanford Prison Experiment; situationist account of behavior; subsequent methodological criticism.
• Daniel Kahneman — behavioral economics; heuristics and biases; prospect theory (with Tversky); Thinking, Fast and Slow; Nobel Prize in Economics 2002.
• Amos Tversky — co-developed heuristics and biases program with Kahneman; would likely have shared Nobel.
• Roger Sperry — split-brain research; Nobel Prize in Physiology or Medicine 1981.
• Paul Broca — localized speech production to inferior frontal gyrus; Broca’s aphasia; also contributed to physical anthropology.
• Carl Wernicke — localized language comprehension to posterior temporal gyrus; Wernicke’s aphasia; also described Wernicke-Korsakoff syndrome (thiamine deficiency with anterograde amnesia and confabulation).
• Harry Harlow — attachment research via surrogate-mother monkey studies; also infamous for isolation chamber (“pit of despair”) experiments demonstrating devastating effects of social deprivation; studies now considered unethical.
• Solomon Asch — conformity line studies; also documented the primacy effect in impression formation (early traits outweigh later ones).
• Martin Seligman — learned helplessness; later founded positive psychology (VIA character strengths, PERMA model of well-being); past APA president.
• Lawrence Kohlberg — moral development stages; Harvard; student of Piaget; died 1987.
• Muzafer Sherif — Robbers Cave experiment; realistic conflict theory; autokinetic effect studies on norm formation.
• Leon Festinger — cognitive dissonance theory; also conducted participant-observation study of a doomsday cult (When Prophecy Fails, 1956) founding work in cult psychology.
• Bibb Latané — bystander effect research with Darley; also social impact theory (influence proportional to number, strength, and immediacy of sources).
• Antonio Damasio — somatic marker hypothesis; Descartes’ Error (1994); The Feeling of What Happens; studied patients with vmPFC lesions.
• William James — functionalism; Principles of Psychology (1890); pragmatism; stream of consciousness; also proposed the James-Lange theory of emotion (bodily changes precede and constitute emotion: “we feel afraid because we run”).
• James-Lange vs. Cannon-Bard theory of emotion — James-Lange: peripheral physiological changes are the emotion; Cannon-Bard (Walter Cannon and Philip Bard): emotional experience and physiological arousal occur simultaneously via the thalamus; Cannon’s critiques of James-Lange (same physiological state for different emotions, viscera too slow) drove later theories.
• Schachter-Singer two-factor theory (1962) — emotion = physiological arousal + cognitive label; misattribution of arousal is possible (excitation transfer); Dutton and Aron’s bridge study (men on a swaying bridge rated an interviewer as more attractive) is a classic demonstration.
• Maslow’s hierarchy of needs — already covered; note that self-transcendence was added above self-actualization in Maslow’s later writings, though the five-level pyramid is the canonical version.
• Carl Rogers — person-centered therapy; unconditional positive regard; congruence (therapist authenticity); empathic understanding; Q-sort method for measuring self-concept; On Becoming a Person (1961).
• Jung’s archetypes — collective unconscious contains universal primordial images: persona (social mask), shadow (repressed self), anima/animus (contrasexual elements), self (totality); individuation is the process of integrating these.
• Alfred Adler — inferiority complex and compensatory striving for superiority; birth order; individual psychology; early break with Freud.
• Karen Horney — proposed three neurotic coping strategies: moving toward people (compliance), moving against people (aggression), moving away from people (detachment); emphasized cultural and relational factors over Freud’s biology.
• Object relations theory — British school (Melanie Klein, Donald Winnicott, Ronald Fairbairn): psychological development driven by internalized representations of self and others (objects); Winnicott’s transitional object (security blanket) as bridge between inner and outer reality.
• Bowlby’s attachment phases — pre-attachment (0–6 weeks), attachment-in-the-making (6 weeks–6–8 months), clear-cut attachment (6–8 months to 18–24 months; separation anxiety and stranger wariness peak), formation of a reciprocal relationship (18–24 months onward).
• Erich Fromm (1900–1980) — German-American psychoanalyst and social psychologist; synthesized Freudian and Marxist thought; argued in Escape from Freedom (1941) that modern individuals flee the burden of freedom into authoritarianism, conformity, or destructiveness; The Art of Loving (1956) treated love as a skill and social practice; coined the concept of the authoritarian character (sadomasochistic submission to authority combined with domination of subordinates); emphasized that character is shaped by socioeconomic conditions, distinguishing him from classical Freudians.
• Bruno Bettelheim (1903–1990) — Austrian-American psychoanalyst; survived Dachau and Buchenau; directed the Sonia Shankman Orthogenic School at the University of Chicago; The Uses of Enchantment (1976) argued that fairy tales perform psychoanalytic work for children by externalizing inner conflicts; controversially attributed childhood autism to emotionally cold “refrigerator mothers” — a theory now discredited; his broader clinical methods have also been reassessed after posthumous revelations about abusive practices; The Empty Fortress (1967) is his major clinical work on autism.
• Myers-Briggs Type Indicator (MBTI) — a widely used personality typology instrument developed by Isabel Briggs Myers and Katharine Cook Briggs in the 1940s, based on Carl Jung’s theory of psychological types; classifies respondents into 16 types along four dichotomies: Extraversion/Introversion, Sensing/Intuition, Thinking/Feeling, Judging/Perceiving; popular in corporate training and personal development but criticized by psychologists for poor test-retest reliability, false dichotomies, and failure to predict behavior as well as the empirically derived Big Five (OCEAN) model; not widely accepted in academic personality research.
• Polygraph — an instrument that simultaneously records multiple physiological responses (heart rate, blood pressure, respiration, galvanic skin response) under the theory that deception produces characteristic autonomic arousal; also called a “lie detector”; widely used in U.S. law enforcement and security screening, but the scientific consensus (National Academy of Sciences, 2003) is that its validity is insufficient for reliable lie detection because the measured arousal is not specific to deception; results are generally inadmissible as evidence in U.S. federal courts; associated with John Larson and Leonarde Keeler in the 1920s.
• Synesthesia — a neurological phenomenon in which stimulation of one sensory pathway involuntarily triggers an experience in another modality; the most common form is grapheme-color synesthesia (individual letters or numbers perceived as inherently colored); also includes lexical-gustatory (words have flavors), chromesthesia (sounds trigger colors), and others; estimated to occur in roughly 1 in 23 people; studied as a window into cross-modal perception, metaphor, and the binding problem in neuroscience; artists and musicians including Vladimir Nabokov and Duke Ellington are notable reported synesthetes.
• Viktor Frankl — existential/logotherapy; Man’s Search for Meaning (1946); experiences in Nazi concentration camps; will to meaning as primary motivator; not a major empirical researcher but a major cultural influence on humanistic/existential psychology.
• Walter Mischel — marshmallow test; also Person-Situation debate: argued (1968) that behavior is more situationally specific than trait theories predict; partly reconciled via interaction (personality × situation).
• Brenda Milner — neuropsychologist who conducted most of the foundational studies with H.M.; established the hippocampus’s role in declarative memory; also discovered that procedural memory is hippocampus-independent.
• Wilder Penfield — neurosurgeon who mapped the cortical homunculus by electrically stimulating cortex during awake brain surgery; patients reported sensations or movements corresponding to specific body parts; homunculus reveals disproportionate representation of hands, lips, and tongue.