Dunning-Kruger Effect

The Dunning-Kruger effect is a cognitive bias in which people with limited competence in a domain overestimate their own ability, while highly competent people tend to underestimate their ability relative to others. First systematically documented by David Dunning and Justin Kruger in 1999, the effect has since been replicated across domains including logical reasoning, grammar, emotional intelligence, and medical knowledge. The mechanism is double-edged: the incompetent lack the metacognitive skill to recognize their own incompetence (they cannot distinguish good reasoning from bad), while the highly competent assume that tasks easy for them are easy for others. The effect has been subject to methodological criticism — some researchers argue that the original findings are partly a statistical artifact of regression to the mean — but the core phenomenon, that the least skilled are systematically poorest at estimating their own skill, is robust across multiple replications. Its implications extend beyond individual psychology into epistemic humility, institutional design, and the question of how peer review can serve as a partial corrective when self-assessment is unreliable. See also: Confirmation Bias, Metacognition.