Marcin Zajenkowski

Who they are

The vault confirmed the paper's record and read its abstract and results. Nothing about Zajenkowski's institution or other work was checked, so none is stated. The paper tested the Dunning-Kruger hypothesis in 929 adults with the Glejser test of heteroscedasticity and quadratic regression, and compared the result with the usual quartile method.

The 2023 exchange with Hiller

In 2023 Avram Hiller published a comment on the 2020 paper in Intelligence (volume 97, article 101732). He argued that the finding of equal prediction error across levels of intelligence does not show that the Dunning-Kruger effect is merely a statistical artefact, and that the result probably comes from the authors' conversion of a comparative self-rating of intelligence onto a linear scale, when a normal scale would have fitted better. He also cautioned researchers working with self-assessed intelligence to watch for measurement problems when ordinal ratings are treated as interval data. Gignac and Zajenkowski replied the same year in Intelligence (volume 97, article 101733), under the title Still no Dunning-Kruger effect. They re-ran the analysis with the transformation Hiller suggested and again found no support for the effect, noted that the one study they could find using a percentile-based approach also largely failed to support it, and encouraged researchers to keep developing new ways to test the hypothesis. The record of the comment and the reply was checked at Crossref, PhilArchive and the University of Western Australia repository on 2026-10-25; the vault read the abstracts and summaries, not the full texts.

Key papers

Gignac, G. E., & Zajenkowski, M. (2020), "The Dunning-Kruger effect is (mostly) a statistical artefact: Valid approaches to testing the hypothesis with individual differences data," Intelligence, 80, 101449.

Gignac, G. E., & Zajenkowski, M. (2023), "Still no Dunning-Kruger effect: A reply to Hiller," Intelligence, 97, 101733.

Key ideas

The quartile method can produce the Dunning-Kruger pattern from the better-than-average effect and regression to the mean.

Two tests that avoid grouping found no effect in the 929-person sample, and the authors concluded that the effect is mostly, rather than entirely, an artefact.

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