Dunning-Kruger effect
To know what you don't know, you first need to know a little.
That less skilled people overrate themselves is well documented. What's debated is how much of the pattern reflects a knowledge problem and how much is a statistical effect.
Sound familiar?
A friend who's just started investing tells you with total confidence where the market is heading. Meanwhile, your economist friend answers every question with "it depends". Who seems to know more?
What it is
The Dunning-Kruger effect describes how people with little skill in an area tend to overestimate their performance. The authors' explanation is that the skills needed to do something well are the same skills needed to realise you're doing it badly.1
There's a second half that people often forget: the most competent people tend to slightly underestimate themselves, because they assume that what comes easily to them is easy for everyone.
The experiment
In 1999, Justin Kruger and David Dunning at Cornell University gave students tests of logical reasoning, grammar and humour. Afterwards, they asked them to estimate how they had done compared with their peers.1
The result was striking: those in the bottom 25% scored around the 12th percentile, yet believed they were around the 62nd percentile, in other words above average.
What we know today
In 2011, Dunning reviewed years of research and found the pattern across very different areas, both in the lab and in real-world settings.2 However, other researchers have pointed out that part of the famous graph may be a statistical artefact: almost everyone rates themselves as "a bit above average", and regression to the mean makes the extremes look more dramatic than they are.
In a study of 929 people, Gignac and Zajenkowski (2020) used stricter statistical methods and concluded that the effect may exist for some skills, but is probably much smaller than previously thought.3
Myth vs. reality
Myth "Stupid people think they're the smartest", or the famous "Mount Stupid" curve.
Reality The original study never drew that curve. It showed that low performers overrate themselves, but still think they did worse than high performers. And it's about specific skills, not general intelligence.
In everyday life
- Be wary of total certainty, in others and in yourself, especially on topics you've only just started learning about.
- Ask for specific feedback from someone more experienced: it's the most reliable way to calibrate yourself.
- If you doubt yourself at something you do well, remember that experts also tend to underestimate themselves.
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. doi.org/10.1037/0022-3514.77.6.1121
- Dunning, D. (2011). The Dunning–Kruger effect: On being ignorant of one's own ignorance. Advances in Experimental Social Psychology, 44, 247–296. doi.org/10.1016/B978-0-12-385522-0.00005-6
- 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. doi.org/10.1016/j.intell.2020.101449