Six ideas run through the entire course: bias, causality, change, measurement, perspective and responsibility. They are not content to memorise. They are tools for thinking, and they are what turns a description of a study into an analysis of it.
📘 What you need to know
The six concepts are bias, causality, change, measurement, perspective, responsibility.
They apply across all three content areas (biological, cognitive, sociocultural) and all four contexts.
They are also Theory of Knowledge concepts, linking psychology to wider questions about how knowledge is made.
You do not need all six in an answer. Three or four relevant ones is usually plenty; two used deeply can be enough.
Concepts overlap. The same idea, such as reductionism, can belong to more than one.
Always apply a concept to the study or context in front of you, never explain it in isolation.
The six, in one question each
Print this. Run any study you meet through the six questions and you will never sit in front of an ERQ with nothing to write.
Bias
Bias is a limitation in objective thinking: information gets filtered through experience, expectations or preferences. In psychology it can shape how research is designed, how data is interpreted, how theories are built, and how people judge things in everyday life. It can be explicit or implicit, and careful design reduces it without ever removing it entirely.
Researcher and participant bias — demand characteristics, social desirability bias.
Sampling bias — opportunity, self-selected or restricted samples limiting generalisability.
Confirmation and publication bias — favouring results that fit the theory, and positive findings being published more often.
Gender and cultural bias, including ethnocentrism — findings from one group applied to everyone.
Cognitive biases — availability, anchoring and representativeness heuristics, in participants and researchers alike.
Credibility and reflexivity — researchers becoming aware of their own assumptions; inter-rater reliability reducing interpretive bias.
Causality
Causality is about establishing cause and effect between variables, and in psychology it is genuinely hard. Behaviour is usually influenced by several interacting variables, relationships can be indirect or bidirectional, and correlation does not imply causation. Controlled methods help, but ethics and practicality limit how much control is possible.
Correlation versus causation, and bidirectional ambiguity — does A cause B, B cause A, or both?
Internal and external validity — can the design support a causal claim, and does it hold outside the study?
Control of extraneous and confounding variables — standardisation, random allocation.
Placebos, double-blind procedures and wait-list controls — ruling out expectancy effects.
Statistical significance and effect size — a significant result can still be practically tiny.
Agency and motivation — human choice complicates any simple causal story.
Change
Change is how behaviour develops, adapts or is altered over time. It can be gradual, like maturation, or sudden, like a shift in mood; planned, like therapy, or unplanned, like illness. Sitting underneath it is the free will and determinism debate.
Development and maturation — natural change that would happen anyway.
Biological and environmental determinism — what constrains or enables change.
Barriers and resistance to change — habits, social pressure, stigma, lack of resources.
Intervention and prevention — and whether treatment effects are meaningful and sustained.
Longitudinal and repeated-measures designs — the only way to tell short-term effects from lasting ones.
Measurement
Measurement is how psychologists observe, define and quantify behaviour. The difficulty is built in: behaviour is often hard to observe directly, depends on context, and is shaped by interpretation. That is why operationalisation matters so much — turning an abstract construct into something you can actually record.
Constructs versus variables — self-esteem is a construct; the score on a scale is the variable standing in for it.
Quantitative and qualitative data, and what each can and cannot show.
Self-reported, empirical and anecdotal data — and the gap between what people say and what they do.
Direct and indirect measures — brain imaging, test performance, physiological responses.
Type I and Type II errors — false positives and false negatives.
Triangulation — using more than one type of evidence to raise credibility.
Perspective
A perspective is a particular way of understanding behaviour. The course uses three — biological, cognitive and sociocultural — and each rests on different assumptions, uses different methods and produces different explanations. No single perspective explains behaviour completely, which is why a multi-perspective approach gives a fuller picture.
Reductionism and holism — break behaviour into parts, or study the interacting whole.
Emic and etic approaches — understanding a culture from inside it, or comparing across cultures.
Deductive and inductive reasoning — theory-driven testing versus data-driven theory building.
Alternative explanations — competing accounts of the same finding.
Cultural and Indigenous perspectives — different ways of knowing, and the importance of cultural meaning in interpretation.
Responsibility
Responsibility covers the ethical and social obligations of psychologists in research and practice: protecting participants, minimising harm, maximising benefit. It also extends beyond the lab — psychologists are responsible for how their findings are used in society.
Informed consent, right to withdraw, protection from harm.
Deception and debriefing — when deception can be justified and what must follow it.
Anonymity and confidentiality — protecting identities and personal data.
Cost-benefit analysis — weighing potential benefit against risk or discomfort.
Animal and child participants — extra safeguards, and justifying that the research is necessary.
Socially sensitive research — avoiding reinforced stereotypes and communicating findings carefully.
Concepts overlap, and that is fine
You will not be asked about a narrow slice of a concept, such as gender bias alone. Questions are set on the whole concept.
🧩 Four questions to ask of any topic you study
How is psychological knowledge constructed here? What counts as evidence in this area?
What assumptions underlie the research or theory? What is being taken for granted?
What limitations affect the findings? Sample, method, measurement, ethics.
How does this connect to other theories, approaches or contexts? Concepts are the connectors.
Do this once per topic, in writing, as you finish it. Ten minutes of concept-tagging when the content is fresh saves hours of panic later, because concept-based essay questions stop feeling like new material.
💡 Exam tip
Define the concept at the start of a concept-based essay, before any study appears.
Apply concepts to the study or context in the question. Explaining a concept in isolation earns little.
Three or four relevant concepts is usually the right number. All six is a warning sign of thin coverage.
Show how two concepts interact where you can, for example bias and measurement, or change and motivation.
Concepts are TOK ideas too, so the same thinking transfers to your TOK essay.
⚠ Common mix-up
Memorising concepts as content. They are tools for thinking, not facts to reproduce.
Forcing all six into one answer. Depth is worth more than coverage.
Confusing perspective with bias. A perspective is a legitimate way of explaining; a bias is a distortion.
Confusing measurement with causality. One asks how well you captured the variable, the other whether it caused anything.
Explaining the concept and never mentioning the study. The application is the mark.
That completes Topic 9. Go back to What Paper 1 Asks For and reread the three sections with the six concepts in mind — the whole exam is those concepts asked in different formats.
Want this explained one-to-one?
Book a free session with an experienced IB Psychology tutor and get your trickiest topics made simple.
