We Can Be Stupid And Know It

Published: May 8, 2023 8.19am EDT

Debunking the Dunning-Kruger effect – the least skilled people know how much they don’t know, but everyone thinks they are better than average

John Cleese, the British comedian, once summed up the idea of the Dunning–Kruger effect as, “If you are really, really stupid, then it’s impossible for you to know you are really, really stupid.” A quick search of the news brings up dozens of headlines connecting the Dunning–Kruger effect to everything from work to empathy and even to why Donald Trump was elected president.

As a math professor who teaches students to use data to make informed decisions, I am familiar with common mistakes people make when dealing with numbers. The Dunning-Kruger effect is the idea that the least skilled people overestimate their abilities more than anyone else. This sounds convincing on the surface and makes for excellent comedy. But in a recent paper, my colleagues and I suggest that the mathematical approach used to show this effect may be incorrect.

What Dunning and Kruger showed

In the 1990s, David Dunning and Justin Kruger were professors of psychology at Cornell University and wanted to test whether incompetent people were unaware of their incompetence.

To test this, they gave 45 undergraduate students a 20-question logic test and then asked them to rate their own performance in two different ways.

First, Dunning and Kruger asked the students to estimate how many questions they got correct – a fairly straightforward assessment. Then, Dunning and Kruger asked the students to estimate how they did compared with the other students who took the test. This type of self-assessment requires students to make guesses about how others performed and is subject to a common cognitive mistake – most people consider themselves better than average.more