Anchoring bias
IB Psychology· Cognitive approach· 14 min read
1. Core concept
Anchoring bias is the tendency to rely too heavily on the first piece of information offered (the 'anchor') when making a judgement, adjusting insufficiently away from it. It is a feature of fast, intuitive (System 1) thinking: even an arbitrary or clearly irrelevant number pulls a later estimate towards itself. It matters because it shows human decisions are systematically, predictably biased rather than fully rational.
2. Key studies
IB Psychology answers must be supported by named studies. Learn these to cite as evidence:
Strack & Mussweiler (1997)
Estimates of Gandhi's age at death were pulled toward an initial anchor, even an absurd one (9 vs 140). — Demonstrates anchoring with a clearly irrelevant anchor — the effect is not just sensible use of information.
Englich, Mussweiler & Strack (2006)
Experienced judges' sentencing decisions were shifted by a randomly rolled number. — Shows anchoring affects even trained experts on consequential, real decisions.
3. Evaluation (AO3)
Strength — robust and consequential — Replicates across trivial and expert, high-stakes contexts, so it is not a lab curiosity.
Limitation — mechanism debated — Whether anchoring works by selective memory access or by insufficient adjustment is still argued, and lab anchors can be more blatant than real-life ones.
4. Scope
5. Common Pitfalls
Wrong move:
Describing anchoring on its own, without linking it to a model of thinking and decision-making.
Why:
A frequently penalised misconception in IB Psychology exams.
Correct move:
In a 'thinking and decision-making' question, tie the bias to the underlying dual-processing model — the bias is the evidence, the model is the answer.
Going deeper
- Dual processing theoryanchoring is explained by the dual-processing model (System 1) — COG_6.