So Hot Right Now: The Dunning-Kruger Effect

15.12.2017 |

Episode #10 of the course How cognitive biases are messing up your decisions by Abasi Latcham


Welcome to the last lesson of the course! We will finish things off with a look at the Dunning-Kruger effect.


What Is It?

In essence, Kruger and Dunning argue that “the skills that engender competence in a particular domain are often the very same skills necessary to evaluate competence in that domain,” meaning those who are incompetent will not know that they are incompetent. The story of a bank robbery will help illustrate this phenomenon.

In 1995, McArthur Wheeler robbed two banks in broad daylight, with no apparent disguise. Not surprisingly, he was found and arrested by police, thanks to surveillance footage. After he was arrested, the police showed Wheeler this footage, who apparently could not believe it: “But I wore the juice!” he exclaimed. What was he talking about?

Well, Wheeler knew that lemon juice could be used as invisible ink (that is, you can write on paper with lemon juice, then heat the paper to make it visible), so he truly believed that if he applied lemon juice to his face, he would be invisible (at least to the cameras). He had some rudimentary knowledge of the chemistry of lemon juice but thought he knew it all. This incident was the impetus for Kruger and Dunning’s original study and led to the formulation of the Dunning-Kruger Effect.

This bias has a corollary too, namely that highly competent people can underestimate their ability and assume that tasks that are easy for them are easy for everyone else too (this is related to the false consensus effect: “I did well, so everyone else must have done well too”).

The Dunning-Kruger effect: With great knowledge, comes great confidence. And with no knowledge, comes great confidence.



Dunning suggests that it’s likely many people have observed the Dunning-Kruger effect at their workplaces but haven’t been able to articulate exactly what they have witnessed.

Driving: A survey shows that up to 80% of people consider themselves to be above average drivers. Because of math, no more than 50% of something can be above average. This indicates that some of these people are suffering under mistaken beliefs attributable to the Dunning-Kruger effect.

Finances: A US survey found that 21% of Americans believe that it’s “very likely” or “fairly likely” that they’ll become millionaires within the next ten years.

Politicians: Some people argue that politicians (especially those you don’t support) are good examples of the Dunning-Kruger effect in action.



What can you do about the Dunning-Kruger Effect? As it is primarily an absence of knowledge, continuous learning is a good first step. Refrain from espousing an opinion on a topic before you have done a bit of research (and reading three online articles from the same source doesn’t count as research).

Consider this story from Zen Buddhism on systematic doubt, and how it can be applied to mitigate the the Dunning-Kruger effect:

A university professor went to visit a famous Zen master. While the master quietly served tea, the professor talked about Zen. The master poured the visitor’s cup to the brim, and then kept pouring. The professor watched the overflowing cup until he could no longer restrain himself. “It’s full! No more will go in!” the professor blurted. “This is you,” the master replied. “How can I show you Zen unless you first empty your cup?”

You cannot learn if you already know everything.

That’s all for this course. Congratulations! And I wish you the best of luck in your lifelong learning endeavors.


Recommended reading

The Burglar with the Lemon Juice Disguise

Are You a Poor Logician? Logically, You Might Never Know

Unskilled and Unaware of it: How Difficulties in Recognizing One’s Own Incompetence Lead to Inflated Self-Assessments by Kruger, Justin, and David Dunning


Recommended video

John Cleese on Stupidity


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