IB Psychology HL cheat sheet

Neurotransmission is excitatory or inhibitory depending on the receptor: Martinez and Kesner found the acetylcholine agonist physostigmine improved rat maze retention, while the antagonist scopolamine impaired it.

Localisation evidence: bilateral hippocampal removal (patient HM) abolished new episodic memory formation while procedural learning such as mirror drawing was preserved, separating declarative from non-declarative memory.

Neuroplasticity: Maguire et al. (2000) correlated posterior hippocampal volume with years of London taxi driving; Draganski et al. (2004) found grey-matter change after juggling practice.

Imaging decision rule: MRI shows structure; fMRI infers function from the BOLD signal (good spatial, poor temporal resolution); PET uses a radioactive tracer for metabolism; EEG gives millisecond timing with poor localisation.

Twin logic: MZ twins share 100% of genes and DZ about 50%, so higher MZ concordance suggests genetic influence, but equal-environment assumptions can inflate the estimate.

Adoption studies separate genes from environment: a trait correlating with biological but not adoptive parents supports a genetic contribution.

Heritability estimate: h-squared is approximately 2(rMZ minus rDZ); it describes variance within a population, not the genetic share of any individual.

Hormone effects: cortisol released via the HPA axis during chronic stress can impair hippocampal-dependent memory; testosterone correlates with aggression but causality is not established.

Evolutionary explanations identify adaptive value and selection pressure, but face the just-so-story and falsifiability criticisms; animal models raise generalisability and ethical issues.

Multi-store model (Atkinson and Shiffrin): sensory memory leads to short-term memory (capacity 7 plus or minus 2 chunks, duration roughly 18 to 30 seconds) and then to long-term memory (unlimited capacity and duration).

Working memory model (Baddeley and Hitch): a central executive controlling the phonological loop and visuospatial sketchpad; the episodic buffer was added in 2000.

Schema effects: Bartlett's 'War of the Ghosts' produced levelling (detail dropped), sharpening (detail emphasised) and assimilation to culturally familiar expectations.

Loftus and Palmer (1974): the verb 'smashed' produced a mean speed estimate of 40.5 mph against 31.8 mph for 'contacted'; a week later the 'smashed' group reported more non-existent broken glass.

Reconstructive memory implies eyewitness testimony is fallible; weapon focus, leading questions and post-event information each raise the risk of distortion.

Flashbulb memories (Brown and Kulik) feel vivid, but Neisser's Challenger study found detail accuracy declined over three years despite high confidence.

Dual-process theory: System 1 is fast, automatic and associative; System 2 is slow, effortful and rule-based; biases arise when System 2 endorses System 1 output without checking.

Heuristics and biases: availability (ease of recall), representativeness (base-rate neglect) and anchoring; framing effects change choices without changing the underlying information.

Emotion affects cognition: high arousal narrows attention and can strengthen consolidation, but confidence in a memory is a poor predictor of its accuracy.

Social identity theory (Tajfel and Turner): social categorisation leads to identification and then comparison; minimal group studies show in-group favouritism arises from mere categorisation.

Social cognitive theory (Bandura): observation depends on attention, retention, reproduction and motivation; vicarious reinforcement means observed consequences shape imitation.

Asch (1951): about 37% of responses on critical trials conformed to a unanimous wrong majority; conformity falls with one dissenting ally or with a private response.

Milgram (1963): 65% of participants continued to the 450-volt maximum when the experimenter accepted responsibility; proximity, authority legitimacy and peer defiance alter obedience rates.

Stereotype threat (Steele and Aronson): diagnosticity and group salience raise anxiety and depress performance; removing the stereotype lifts scores.

Illusory correlation (Hamilton and Gifford): distinctive groups and distinctive behaviours are over-associated, so stereotypes form from sparse and unrepresentative data.

Hofstede dimensions: individualism-collectivism, power distance, uncertainty avoidance, masculinity-femininity, long-term orientation and indulgence; individualist cultures show a stronger fundamental attribution error.

Berry's acculturation: integration (maintaining heritage and adopting host culture) is usually linked to the best psychological outcomes and marginalisation to the worst; the model is criticised for treating host attitudes as static.

Cultural dimensions are national averages and cannot predict an individual; within-culture variation usually exceeds between-culture differences.

Four definitions of abnormality: statistical infrequency (beyond two standard deviations from the mean), deviation from social norms, failure to function adequately, and deviation from ideal mental health (Jahoda).

Diagnostic systems: DSM-5-TR (American Psychiatric Association) and ICD-11 (WHO); both require symptom counts, minimum duration and impairment criteria.

Rosenhan (1973): eight pseudo-patients were admitted reporting hearing voices and none were detected; diagnostic labels persisted in records after normal behaviour resumed.

Reliability concerns centre on inter-rater agreement and structured interviews; validity concerns include comorbidity, symptom overlap, and cultural and gender bias (Broverman et al.).

Culture-related presentations include taijin kyofusho (Japan), koro (Southeast Asia) and ataques de nervios (Latin America); DSM-5-TR includes a cultural formulation interview.

Depression aetiology: biological (heritability, serotonin and cortisol, 5-HTTLPR variants), cognitive (Beck's negative triad and dysfunctional schemas; Ellis's ABC model) and sociocultural (Brown and Harris vulnerability factors).

Brown and Harris (1978): women with a provoking agent plus a vulnerability factor (loss of mother before age 11, lack of a confidant, three or more children under 14) had markedly higher depression risk.

Treatment evaluation: SSRIs raise synaptic serotonin, but Kirsch et al. found only small advantages over placebo in mild-to-moderate depression; CBT targets distorted cognitions and relapse prevention.

Effectiveness decision rule: randomised controlled trials with placebo controls establish efficacy; blinding, allocation concealment and dropout rates determine how much weight a trial deserves.

Qualitative data are non-numerical meanings (interview transcripts, field notes, texts); quantitative data are numerical measurements; mixed methods combine both within one study.

Sampling decision rule: purposive for information-rich cases, snowball for hidden populations, convenience for accessibility; none of these supports statistical generalisation.

Lincoln and Guba's trustworthiness criteria: credibility, transferability, dependability and confirmability, the qualitative counterparts of internal validity, external validity, reliability and objectivity.

Credibility strategies: triangulation (data, investigator, method, theory), member checking, prolonged engagement, peer debriefing and negative case analysis.

Thematic analysis (Braun and Clarke): familiarisation, initial codes, searching for themes, reviewing themes, defining and naming themes, then reporting; themes are patterns of meaning, not topic summaries.

Inductive content analysis codes manifest content into categories emerging from the data; deductive analysis codes data against a pre-existing theoretical framework.

Reflexivity and positionality: researchers document how their background and relationship to participants shape access, interpretation and reporting; a reflexive journal supports confirmability.

Ethics in qualitative work: informed consent, confidentiality versus anonymity, right to withdraw, protection from harm, and special care with covert observation or deception.

Interview types: structured (fixed questions, comparable), semi-structured (guide with probes, flexible) and unstructured (participant-led); leading questions and interviewer effects threaten validity.

IA report structure: introduction (background, aim, hypotheses), method (design, participants, materials, procedure), results (descriptive and inferential), discussion (interpretation, limitations, extensions), references and appendices.

Operationalise the independent and dependent variables so another researcher could replicate: state exactly what was manipulated and how the dependent variable was measured.

Hypotheses: a research hypothesis predicts an outcome (directional or non-directional); the null hypothesis states no difference; both are stated before data collection.

Design choice: independent samples avoids order effects but needs more participants; repeated measures controls participant variables but requires counterbalancing; matched pairs is a compromise.

Control extraneous variables with standardised instructions, scripts, timing, materials and setting; use single- or double-blind procedures to reduce demand characteristics and experimenter bias.

Descriptive statistics: mean (uses all scores, sensitive to outliers), median (ordinal data), mode (categorical data) and standard deviation (spread); group means are shown on a bar chart with error bars.

Inferential decision rule: Mann-Whitney U for two independent groups, Wilcoxon signed-rank for repeated measures, both requiring at least ordinal data; reject the null when the observed value is more extreme than the critical value at p less than or equal to 0.05.

Ethics in the IA: informed consent, right to withdraw, no deception, debriefing, confidentiality and protection from harm; participants under 16 require parental consent.

Report conventions: raw data and calculations belong in the appendix, results are reported without interpretation, and the discussion links findings to background research and notes limitations.