The Overconfidence Effect: The Mistakes of the Smart

What is this page about?

An explainer of the overconfidence effect, the systematic gap between felt certainty and actual accuracy, opening with Lichtenstein and Fischhoff's finding that people 90% confident were right only about 75% of the time and Alpert and Raiffa's overly narrow 90% confidence intervals. It presents a taxonomy of three forms (overestimation, overplacement, and overprecision), the cognitive science of excessive certainty, the intellectual lineage, the empirical research, and the limits and nuances of the effect.

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Every accepted correction to this page is recorded with the exact change, so readers can see how the page improved over time.

1. 11 July 2026 · corrected by Emir Baycan

   First names swapped; paper is by Justin Kruger and David Dunning

   Before

   David Kruger and Justin Dunning's 1999 paper

   After

   Justin Kruger and David Dunning's 1999 paper

   Why: Corrected swapped first names: the 1999 paper is by Justin Kruger and David Dunning. Verified already live in body content and bibliography; FAQ mentions the Dunning-Kruger effect by name only, with no first names to correct.

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