IB Psychology SL common mistakes
IB Psychology SL · Understand the traps and how to avoid them.
Describing a biological study (e.g., a twin or lesion study) without ever stating the biological mechanism it is meant to demonstrate, so the answer reads as a summary of the procedure rather than an explanation of behaviour.
Candidates memorise study procedures (participants, method, results) as a narrative and treat the mechanism as implicit. The command term is often 'explain' or 'discuss', but the habit of retelling the study crowds out the causal chain from biology to behaviour.
What to do instead
Before writing, draft a one-sentence mechanism claim (e.g., 'variation in hippocampal volume is associated with spatial memory performance because the hippocampus supports spatial encoding'). Then structure the paragraph as claim → study evidence → link back to the claim. If the sentence 'this shows that [biological factor] affects [behaviour] because…' cannot be written, the study has not been used.
Treating localisation of function as a single fixed map, asserting that one brain area 'is responsible for' a complex behaviour, and ignoring plasticity, distributed networks, or contradictory lesion evidence.
Textbook summaries simplify localisation into tidy area-to-function pairs, and candidates reproduce these as certainties. Evaluation of localisation is a standard demand, but the nuance (equipotentiality, recovery, individual variation) is easily lost under exam pressure.
What to do instead
Use hedged causal language ('is strongly associated with', 'contributes to') and include at least one limitation that names an alternative explanation: plasticity after damage, distributed processing, or studies where damage to the same area produced different outcomes. Pair a localisation study with a plasticity or network study so the answer shows the debate rather than one side.
Confusing correlation with causation when interpreting genetic or neuroimaging findings, for example concluding that a gene 'causes' a behaviour from a heritability estimate or that an activated brain region 'proves' a cognitive process.
Heritability figures and brain scans look authoritative and quantitative, so candidates treat them as direct proof. The distinction between inherited influence, environmental interaction, and reverse inference from brain activation is conceptually demanding and rarely rehearsed explicitly.
What to do instead
Practise writing an explicit limitation sentence for every biological study: state what the design can and cannot show (heritability estimates describe population variance, not individual causation; activation is correlational and subject to reverse inference). Use adoption or gene–environment interaction studies as counter-evidence when arguing against simple genetic determinism.
Describing a cognitive model (e.g., working memory or schema theory) in abstract terms with no supporting empirical study, or citing a study without saying which component of the model it supports.
Models are taught as diagrams and labels, so candidates reproduce the components faithfully but never connect them to data. Under time pressure the model description expands and the evidence is dropped.
What to do instead
For each model, memorise one study per key component and write the link explicitly ('dual-task performance deteriorated only when both tasks drew on the phonological loop, supporting a modality-specific store'). Aim for a fixed ratio: roughly one third model description, two thirds evidence and evaluation.
Evaluating cognitive research only with generic strengths ('it was a lab experiment so it was controlled') instead of addressing the specific methodological issue, such as ecological validity of memory tasks, demand characteristics, or the artificiality of stimuli.
Candidates learn a stock list of evaluation phrases and apply them regardless of the study. Generic evaluation earns little credit because it does not engage with what the study actually measured.
What to do instead
Before the exam, build a short evaluation bank per paradigm (word lists, dual-task, eyewitness tasks) naming the concrete problem and its consequence for the theory. In the answer, tie the limitation to the conclusion: 'because the task used nonsense syllables, the finding may not generalise to meaningful memory, weakening the claim that…'.
Presenting reconstructive memory or schema effects as if they show memory is simply unreliable, without distinguishing encoding, storage, and retrieval, or without acknowledging that schema effects are often adaptive and modest in size.
Eyewitness research is memorable and dramatic, and candidates overgeneralise it into a claim that all memory is distorted. The cognitive processes underlying the effect are glossed over.
What to do instead
Specify the stage at which distortion occurs (encoding, storage, or retrieval) and cite the paradigm that isolates it. Add a balancing point: schema-consistent processing supports efficient recall, and effect sizes vary with delay, arousal, and interviewing method. This turns a sweeping claim into a precise, evaluable one.
Writing about the sociocultural approach as individual psychology with a group mentioned, for example explaining conformity purely by personality or explaining prejudice by individual cognition, without identifying a social or cultural level of analysis.
Candidates carry over explanations from the cognitive and biological approaches because those are more familiar, and the sociocultural approach's defining feature (situational and cultural influence) is not made explicit in their notes.
What to do instead
For every sociocultural answer, state the level of analysis in the first sentence ('this explanation locates the cause in group norms and social identity rather than individual traits'). Then ensure the evidence manipulates or measures a social variable (group size, in-group membership, cultural dimension) rather than an individual difference.
Treating cultural findings as universal or as fixed national traits, generalising from one sample (often Western undergraduates or one small-scale society) to 'humans' or to all members of a culture.
Classic studies are presented as general findings, and cultural dimensions are taught as country-level labels, which encourages essentialist reading. The problem of WEIRD samples and within-culture variation is easy to state but rarely applied.
What to do instead
Name the sample and its limits in the same breath as the finding, and distinguish individual-level from culture-level claims. Use a cross-cultural comparison to show both difference and similarity, and add a sentence on within-culture variation so the answer avoids treating culture as destiny.
Citing a classic obedience or conformity study with inaccurate or embellished details (wrong procedure, invented percentages, or a result that did not occur), or citing a study that does not actually support the stated claim.
Details are learned from secondary summaries and drift over time; candidates also stretch a well-known study to fit a question it does not address because it is the only one they can recall.
What to do instead
Keep a one-line fact card per core study: aim, procedure in one sentence, one key numerical result, one limitation. Verify each number against a reliable source before the exam. If the study does not fit the question, say so and use a better one rather than forcing the fit.
Ignoring the command term and the marks available, so a 'describe' question receives an unbalanced evaluation, or a 'discuss' question receives description only, and the three approaches are never integrated when the question asks for comparison.
Candidates answer the topic they revised rather than the question asked, and under time pressure they default to whatever content flows most easily. Command terms are treated as decoration rather than as instructions about structure.
What to do instead
Underline the command term and note its demand before writing: describe = accurate detail, explain = mechanism and causal links, discuss/evaluate = evidence plus balanced appraisal, compare = explicit similarities and differences. Allocate time by marks and, for integrative questions, write one paragraph per approach followed by a synthesis paragraph that states where the approaches agree, conflict, or operate at different levels.