Dunning-Kruger effect
People with low skill in a domain tend to overestimate their performance, partly because the knowledge needed to do well is the same knowledge needed to judge how well you did. High performers slightly underestimate themselves.
What drives it
Explains why feedback often fails to land with those who most need it and why self-assessment is a weak guide to competence. In the original data the weakest still rated themselves below the strongest; they were overconfident, not the most confident. Its real use is as a warning against mistaking confidence for skill, not as a label for other people.
How it shows
Work
The new manager who doesn't know what they don't know about handling a performance problem. Appraisal self-ratings that track manager and peer ratings only loosely. The larger judgement error at work is the observer's: mistaking confidence for competence when hiring and promoting.
Relationships
The relative who is sure about medicine or investing after a few videos. Arguments in which one person cannot see the gap in their knowledge. Notice too how often the term itself is used as an insult to dismiss someone who disagrees.
Self
The useful check is narrow: in domains where you have little training and no external feedback, treat your self-assessment as unreliable. Reaching for 'Dunning-Kruger' to explain why someone disagrees with you is the bias blind spot at work.
What tells it apart
Confidence-competence gap in leader selection: The confidence-competence gap is about observers selecting leaders for confidence and shows in who gets promoted; Dunning-Kruger is about a person's own self-assessment and shows in self-ratings against test scores.
Grandiose narcissism: Grandiose narcissism inflates the self-view across domains and meets correction with anger; the Dunning-Kruger pattern is domain-specific and usually corrects with training and feedback.
Impostor phenomenon: Impostor feelings are skilled people underrating themselves with anxiety; Dunning-Kruger is unskilled people overrating themselves without it.
A test
Compare self-assessment with an objective measure in one specific domain, then see whether the gap narrows after training; a gap that closes with skill is the effect, one that persists across domains points to personality instead.
Questions to carry
- In this one skill, how does the person's own rating compare with a measure that doesn't depend on their view?
- Where am I most confident in my judgement while knowing least about what doing it well looks like?
How strong the research is
mixed. Low performers do overestimate themselves, but part of the classic pattern is produced by regression to the mean and the general better-than-average effect, and the popular claim that the least competent are the most confident is not supported.
Where it comes from
Justin Kruger and David Dunning, 1999; critiques by Joachim Krueger and Ross Mueller, 2002, Edward Nuhfer and colleagues, 2016, and Gilles Gignac and Marcin Zajenkowski, 2020
Sources
- Tomas Chamorro-Premuzic, Why Do So Many Incompetent Men Become Leaders? (And How to Fix It) (2019)