Calibration Certificate No. anchoring
Anchoring
Anchoring is the tendency for an initial reference value, even an arbitrary or irrelevant one, to pull subsequent numerical estimates and judgments toward it.
the pull of a visibly random anchor on the median estimate (wheel-of-fortune, Tversky & Kahneman 1974)
Anchoring is among the more reliably reproduced effects in social/cognitive psychology: it was successfully replicated in the Many Labs project (Klein et al., 2014; total N=6,344 across ~36 labs), where anchoring tasks were among the largest and most robust effects, and multiple meta-analyses report large effects with effect sizes similar in published and unpublished studies (Röseler and colleagues' Open Anchoring Quest work). However, the magnitude is contested: high-powered re-evaluations find much smaller effects than the underpowered originals. Li, Weigel, Ferraro & Messer (2025, Economic Inquiry) raised power from 46% to 96% and found a 3.4% effect (95% CI [-3.4%, 10%]) where the original reported ~31% — about seven times smaller, with a CI including zero. So the existence of anchoring replicates well, but classic effect sizes appear inflated.
Calibration record
Source of systematic error
Two mechanisms are now distinguished by anchor type. For experimenter-provided (external) anchors, the dominant account is the selective accessibility model (Strack & Mussweiler, 1997): testing the hypothesis that the anchor is the answer selectively activates anchor-consistent information, which then biases the absolute judgment, much like semantic priming. For self-generated anchors (e.g., starting from a known value and adjusting), Epley and Gilovich (2001, 2006) revived the original anchoring-and-adjustment account: people adjust away from the anchor but stop at the near edge of a plausible range, yielding insufficient adjustment.
The original Tversky-Kahneman 'insufficient adjustment' explanation was challenged by selective-accessibility/priming accounts in the 1990s. Epley and Gilovich reconciled them as a dual-process picture: adjustment for self-generated anchors, accessibility/priming for provided anchors. Numeric-priming and conversational-inference accounts have also been proposed.
Recalibration procedure
Consider-the-opposite: deliberately generate reasons the true value could be far from the anchor (especially much lower/higher), and where possible source your estimate from independent data before any reference number is shown. Mussweiler, Strack & Pfeiffer (2000) found that explicitly considering anchor-inconsistent arguments reduced the anchoring bias.
Mussweiler, Strack & Pfeiffer (2000), 'Overcoming the Inevitable Anchoring Effect: Considering the Opposite Compensates for Selective Accessibility,' Personality and Social Psychology Bulletin, 26(9), 1142-1150, showed the consider-the-opposite strategy attenuates anchoring; forewarning alone is generally weak.
Cross-calibrated against
- Anchoring-and-adjustment heuristicparentThe broader heuristic (one of Tversky & Kahneman's three) under which the anchoring bias falls.
- FocalismsiblingA closely related anchoring-type bias in affective forecasting: over-weighting a focal event when predicting future feelings (Wilson et al., 2000).
- Confirmation biasmechanistically-linkedSelective accessibility — testing whether the anchor is the answer and recruiting anchor-consistent information — overlaps with confirmatory hypothesis testing.
- Insufficient adjustmentchildThe specific sub-mechanism for self-generated anchors: people adjust away from a starting value but stop too soon.
- Primingeasily-confusedFor provided anchors, anchoring behaves like a special case of semantic/numeric priming, which can blur the distinction.
- Status quo biassiblingBoth involve a reference point exerting gravitational pull on judgment, but status quo bias concerns choices/defaults rather than numeric estimates.