The Dunning-Kruger Effect states that people with the lowest competence tend to overrate their competence, but people with the highest competence tend to underrate themselves. This was shown in 1999 paper by Dunning and Kruger.1 Here’s one of the figures from the paper:
The Dunning-Kruger effect has entered popular wisdom, and is frequently brought up whenever people feel like they’re dealing with someone too stupid to know how stupid they are. But does the research actually mean what people think it means?
Before reading into this subject, I must admit that I had a major misconception. I thought that people’s self-assessment was actually anti-correlated with their competence. I thought someone who knew nothing would actually be more confident than someone who knew a lot. (This leads to an amusing dilemma: Should I choose to give myself a lower rating, because it would that increase posterior probability that I’m more competent?2)
But it is not true. People who know nothing are less confident than people who know a lot. People who know nothing are overconfident relative to their actual ability, but they are still not as confident as people who have high ability.
More self-aware, or just lucky?
Dunning and Kruger argue that the Dunning-Kruger effect arises because people with less competence are also worse at self-assessment. But there is, in fact, an alternative explanation.3
Let’s suppose that people are completely ignorant of their own ability. On average, everyone gives themselves the same rating, regardless of their actual ability. People tend to be overconfident in general, so let’s just say that people rate themselves in the 70 percentile. In this scenario, you might find that the people in the bottom 25% are very overconfident, rating themselves in the top 30%. In contrast, people in the top 25% would have very accurate self-ratings.
But does that really mean that people with greater ability are better at assessing their own ability? Or are they just lucky that the guess they made–which is the same guess that everyone makes–happens to align with the correct answer? Perhaps it’s not that competent people are better at self-assessment, it’s that everyone is very confident in themselves, and only some people have the ability to match that confidence.
There is also a subtler statistical argument being made. It is not merely that people are bad at assessing their own skills, it’s that the tests are also bad at assessing their skills. If the tests are completely unreliable, you expect that the test results will have no relation to people’s self-assessments.
In practice, people aren’t completely ignorant of their own ability, and the tests are at least somewhat reliable. As a result, people who perform better on the test are slightly more confident in themselves. Nonetheless, this interpretation casts doubt on the Dunning-Kruger effect.
Overconfidence is American
Which interpretation is correct? This could be tricky to discern, since both interpretations make similar predictions. Dunning and Kruger, for their part, reject the statistical argument, based on analysis of their data.4 However, I feel they have not sufficiently addressed the hypothesis that basically everyone is ignorant of their own ability.
One interesting fact I discovered is that self-ratings are culturally dependent. East Asians systematically underrate themselves, compared to USians The researchers claim that this actually has some utility: USians tend to work harder when they think they’re good at something, whereas East Asians tend to see failure as an invitation to try harder.
If this is true, it implies that among East Asians, people with lower competence are more accurate in their self-assessments. This appears to directly contradict the Dunning-Kruger interpretation. But perhaps you shouldn’t take my argument too seriously, since I’m not backing it up with any data.
The next time you see the Dunning-Kruger effect used to mock someone’s intelligence, it would be wise to remember that this is a real area of psychology research, one which you may not know much about. Real research is often more muddled and complicated than people make it out to be in popular media, and this is no exception.
Every month I repost an article from my archives. This month, I had major issues with the article I wrote in 2015, so I ended up rewriting it substantially. So it’s not exactly a repost, but it’s taking the monthly repost slot.
1. Kruger, J. and Dunning, D. “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), 1121–34 (1999). (return)
2. This dilemma is a form of Newcomb’s paradox. If you’re a one-boxer, you might prefer to rate your own ability in the way that maximizes the expectation value of your actual competence. If you’re a two-boxer, you might say that this isn’t a consideration, because how you rate yourself has no causal connection to your actual competence. (return)
3. Ackerman, P. L. et al. “What We Really Know About Our Abilities and Our Knowledge”. Personality and Individual Differences 33, 587-605 (2002). (return)
4. Ehrlinger, J. et al. “Why the Unskilled Are Unaware: Further Explorations of (Absent) Self-Insight Among the Incompetent”. Organizational Behavior and Human Decision Processes 105 (1), 98-121 (2008). (return)