The least competent people are the most overconfident (Dunning–Kruger effect).
Verdict: contested
Almost everyone misjudges themselves toward the average; much of the classic pattern is a statistical artefact.
What the evidence shows
Kruger & Dunning (1999) reported that low performers grossly overestimated their ability while top performers slightly underestimated theirs, and argued the incompetent lack the skill to recognise their own incompetence. The catchy pattern became internet shorthand for other people's overconfidence.
Later analysts pointed out that the classic chart appears partly from regression to the mean and the mathematics of noisy self-estimates: because self-assessments are imperfect, everyone's guess is pulled toward the average, which automatically makes low scorers look overconfident and high scorers look modest — even with random data. Gignac & Zajenkowski (2020) showed the effect is 'mostly a statistical artefact.' Some genuine metacognitive gap may remain, but the strong, tidy story is contested: overconfidence is widespread, not a special property of the least able.
Sources
Kruger, J., & Dunning, D. (1999). Unskilled and unaware of it: How difficulties in recognizing one's own incompetence lead to inflated self-assessments.
Journal of Personality and Social Psychology, 77(6), 1121–1134
Bottom-quartile performers overestimated their percentile rank far more than top performers, interpreted as a metacognitive deficit.
DOI: 10.1037/0022-3514.77.6.1121 →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
Using methods robust to regression to the mean, the classic effect largely disappears, indicating much of it is a statistical artefact.
DOI: 10.1016/j.intell.2020.101449 →