IB Diploma Programme Psychology SL (first assessment 2021; current guide). This topic covers the CORE's third approach in full — the sociocultural approach (the individual and the group, cultural origins of behaviour and cognition, cultural influences on attitudes and identities) — and then the OPTIONS menu: abnormal psychology, developmental psychology, health psychology and the psychology of human relationships (SL schools teach ONE option; this handout equips all four so any school's choice is covered). Every claim travels with a named study, and the classic findings' numbers are as published.

Must-know for the sociocultural core and options:

Social identity theory 社会认同理论 (Tajfel and Turner) explains intergroup behaviour in three steps — SOCIAL CATEGORISATION (sorting self and others into groups), SOCIAL IDENTIFICATION (adopting the in-group's identity) and SOCIAL COMPARISON (favouring the in-group to build self-esteem). TAJFEL'S MINIMAL GROUPS (1971): Bristol schoolboys allocated by a coin-flip-like criterion (dot estimation) still awarded more points to their own anonymous group — mere categorisation produces in-group favouritism. Stereotypes are schemas about groups — quick but resistant to contrary evidence; STEELE and ARONSON (1995) showed stereotype threat 刻板印象威胁: Black students performed worse than White students only when a test was framed as diagnostic of ability, showing the stereotype doing measurable work.

SOCIAL INFLUENCE. Conformity 从众 — Asch (1951): judging line lengths against a unanimous wrong majority, about 75% of participants conformed at least once and roughly a third of critical trials went with the majority; one dissenting ally collapses conformity. Obedience 服从 — Milgram (1963): 26 of 40 participants (65%) administered the full 450 V in a staged learning experiment — ordinary people follow destructive orders under graduated authority and proximity. The two differ in the source of pressure (peers' unanimity versus authority's commands), and both are culture-sensitive: Bond and Smith's meta-analysis found conformity lower in individualist cultures.

CULTURE. Cultural dimensions 文化维度 (Hofstede) — individualism versus collectivism, power distance, uncertainty avoidance, masculinity (later long-term orientation) — describe national value systems from workplace surveys; the trap is the ecological fallacy: describing cultures, never individuals. Enculturation 文化濡化 is learning one's own culture's norms; conformity studies double as evidence that norms are culture-bound (as the drift of Asch's effect across decades and countries shows). Acculturation 文化适应 follows when cultures meet: Berry's four strategies — ASSIMILATION (adopt, abandon), INTEGRATION (adopt and keep), SEPARATION (keep, avoid), MARGINALISATION (neither) — with INTEGRATION generally the healthiest profile.

Bicultural identity: Benet-Martínez shows people can hold two cultural frames with varying integration — biculturals switch interpretive frames with cultural cues (frame switching), and higher identity integration predicts wellbeing. Acculturation research links STRATEGY to OUTCOME: integration associates with better mental health, marginalisation with the worst (Berry's comparative studies) — evidence that identity negotiation, not contact alone, carries the stress.

THE OPTIONS (SL schools teach one; each below is a complete mini-kit of explanations, one anchor study and application). ABNORMAL PSYCHOLOGY — diagnosis 诊断: DSM/ICD categories rest on reliability and validity; ROSENHAN (1973) sent 8 pseudopatients to 12 hospitals complaining of one symptom; all but one were admitted with schizophrenia, kept 7–52 days, and were discharged "in remission" — the label shaped how staff read ordinary note-taking, while real patients often saw through it. Etiology of major depression: biological (genetic liability, monoamine activity), cognitive (Beck's negative triad; learned helplessness) and sociocultural (life events, isolation) — multi-factorial by default. Treatment: CBT restructures the triad with effects comparable to SSRIs and lower relapse after withdrawal; combined treatment leads for severe cases. DEVELOPMENTAL PSYCHOLOGY — brain development: Romanian orphanage research (Rutter's ERA) shows severe early deprivation impairing later cognition and attachment, with earlier adoption buying better catch-up; cognitive development: false-belief understanding appears around age four (Wimmer–Perner's Sally–Anne task), mapping Piagetian stages onto theory of mind; identity development: Erikson's stage crisis and Marcia's identity statuses (achievement, moratorium, foreclosure, diffusion); developing as a learner: metacognition and attributional style, not "learning styles", move performance. HEALTH PSYCHOLOGY — determinants: the socioeconomic gradient (Whitehall II: lower employment grade, higher mortality, independent of access); stress: chronic cortisol impairs immune function — Kiecolt-Glaser's caregivers' wounds healed markedly slower than controls'; health promotion: the health-belief model (perceived susceptibility, severity, benefits, barriers, cues) predicts screening uptake where fear alone does not. PSYCHOLOGY OF HUMAN RELATIONSHIPS — personal relationships: formation follows proximity, similarity and perceived attractiveness — in Walster's computer-dance study the partner's rated attractiveness, not one's own, predicted liking; group dynamics: SHERIF's Robbers Cave showed intergroup hostility built by competition and reversed by superordinate goals 超级目标; social responsibility: bystanderism 旁观者效应 — Darley and Latané's seizure study: 85% helped alone against 31% with four others believed present (smoke version: 75% against 10%) — diffusion of responsibility 责任扩散, not apathy.

• Social identity theory's three processes with Tajfel's minimal groups; stereotypes and Steele–Aronson's stereotype threat (sociocultural).
• Asch's ≈75%/≈37% with the ally effect; Milgram's 26/40 = 65% with the graduated-commitment mechanism; conformity versus obedience (sociocultural).
• Abnormal: Rosenhan's 8/12/7–52 days; depression's three-level etiology; CBT versus SSRIs.
• Developmental: Rutter's orphans; Sally–Anne at ~4; Marcia's statuses; metacognition as the learner lever.
• Health: the Whitehall II gradient; Kiecolt-Glaser's slow-healing caregivers; the health-belief model's five parts.
• Relationships: Walster's attractiveness finding; Sherif's superordinate goals; Darley–Latané 85%/31% and diffusion of responsibility.

Boundary notes: Paper 1 Section A SAQs [9] want one precise study per concept; the option paper's essays [22] demand ERQ evaluation — strengths, limitations, assumptions. All numbers are the published classic results.