DunningKruger

The Dunning-Kruger effect is a cognitive bias in which people with low ability in a domain overestimate their own competence, while those with high ability may underestimate their relative skill. It arises from metacognitive deficits that impair both performance and judgment.

The effect was described in a 1999 study by David Dunning and Justin Kruger, researchers at Cornell University, based on experiments in humor, logic, and grammar. In the studies, participants with low test scores consistently overestimated their performance, whereas those with high scores slightly underestimated their relative standing. The researchers framed the findings as a miscalibration between subjective confidence and actual performance.

The proposed mechanism centers on deficiencies in metacognition: people lacking skill also lack the ability to recognize their own errors, which leads to inflated confidence. Conversely, highly competent individuals may assume tasks are easy for others and underestimate their relative advantage.

The Dunning-Kruger effect has been examined across various domains, including academics, workplace, and everyday judgments. It is often cited as a factor in poor decision-making and overconfidence, though the size of the effect and its universality remain debated.

Critics note that replication and effect sizes vary; some studies point to methodological confounds such as measurement bias, sample selection, or statistical regression to the mean. The concept is often discussed alongside broader phenomena related to calibration and overconfidence, rather than as a single universal principle.

In practical terms, recognizing the effect has led to an emphasis on feedback, calibration training, and explicit performance benchmarks to improve self-assessment.