The Dunning-Kruger Effect: It’s Your Confidence, Stupid

The Dunning-Kruger effect can help us make sense of the gap between self-assessments of competence and reality.

Pittsburgh, 1995. A rotund, sore-eyed man by the name of McArthur Wheeler walks into a bank in broad daylight. If you’re there, you can’t miss him. There is no visible attempt at disguise, despite numerous surveillance cameras capturing the moment that follows – and he knows that. The cameras are no bother.

He approaches the cashier, points his gun, and collects his winnings. Then he leaves the bank and proceeds to rob another, again seemingly throwing caution to the wind.

By 11pm on the same day, the police have clear images of his face broadcast on the local news. By midnight, there’s a knock on Wheeler’s door. The game is up. He can’t believe it: “But I wore the juice,” he mumbles as police take him away.

Here’s where it all gets even odder. Wheeler soon reveals the full extent of his failed plan to police: invisibility.

The “juice”, you see, was lemon juice. And knowing that lemon juice was used as an invisible ink, Wheeler concluded that it would also make his face invisible to surveillance cameras. He even tested the theory by taking a photo of himself while his face was covered in lemon juice. His face disappeared! (presumably because his photography skills were as bad as his bank robbing skills).

Amused police concluded that Wheeler wasn’t mad or joking. Quite simply, his own perception of his knowledge of invisibility was widely out of kilter with reality.

The plan, then, was fool-proof in Wheeler’s eyes – but utterly foolish in everybody else’s. Which, coincidentally, brings us to another problem with his scheme: his eyes. Wheeler admitted to police that the lemon juice stung his eyes so badly that he could barely see.

What Is the Dunning-Kruger Effect?

The tale of McArthur Wheeler’s brief and incompetent stint as a bank robber is one of the most ridiculous delusions imaginable. And that’s precisely why it caught the interest of two psychology professors from Cornell University.

In 1999, David Dunning and Justin Kruger published a paper entitled “Unskilled and Unaware of It”. They opened with a brief account of this tale. The ideas that followed would later become known as the Dunning-Kruger effect.

In a nutshell, the Dunning-Kruger effect is a cognitive bias in which people assess their ability level as higher than it is in reality. Dunning and Kruger’s work demonstrated that this gap between self-assessment and reality tends to be particularly pronounced for those with lower ability. Across four different tests, they found that those in the bottom quartile of ability grossly overestimated their test performance and ability across tests for grammar, logic and even humour.

As Dunning and Kruger put it in their paper:

Not only do these people reach erroneous conclusions and make unfortunate choices, but their incompetence robs them of the metacognitive ability to realize it.

In other words, those who are incompetent are often too incompetent to see they are incompetent. Returning to poor old Mr Wheeler, we begin to see why in his own incompetent echo chamber, he convinced himself that lemon juice would make his face invisible.

The Knowledge-Confidence Curve

But the Dunning-Kruger effect is not an affliction reserved for the stupid.

I’m guilty of it, you’re guilty of it, your friends are guilty of it – the whole world is guilty of it. And that, unfortunately, puts us all at risk of shoddy decisions from time to time. These decisions may not leave us with stinging eyes, but they can sting just about every major part of our lives: relationships, health, careers, bank balances.

The question, then, is how can we ensure we don’t fall into the pattern?

The best way to answer this question is to first consider how confidence in our ability and actual level of ability look on a simple graph.

The second point on this graph, where confidence spikes and knowledge remains low, is the territory in which decisions can be most adversely affected. This is where blind ignorance rules the day – where lemon juice gets used as a cunning disguise, and where we end up hurt, broke, embarrassed, arrested or even dead because of our unjustified confidence in our abilities. In short, this is the Dunning-Kruger effect in action.

But there is good news for learners. Dunning and Kruger also showed that improving our skills can help us recognise our own limitations, bridging this dangerous gap between self-perception and reality.

As our level of competence improves, we may still overestimate our ability, but the gap no longer poses the same level of risk to our decisions. Our confidence may decline from its previously unjustified heights as we question how much we actually know. And finally, as we reach expert level, our confidence will rise justifiably.

Knowledge Is Power, but Not Necessarily Confidence

It’s knowledge of this pattern which can help regulate our choices while we’re on the learning journey. For those of us ready to accept we’re not the finished article, awareness of the knowledge-confidence curve can keep us in check. It can push us to develop our knowledge further, while regulating our confidence and decision making.

We can do this with one simple starting proclamation: If you’re relatively new to something, you’re not anywhere near as good at it as you think you are.

The Dunning-Kruger effect can also help us make sense of the actions of others. It can help explain why some people grossly overestimate their performance in annual appraisals, or why somebody with no experience of stock trading ends up chucking away their life’s savings. It can explain why people with absolutely no hope of advancing past the auditions put themselves through the painful televised embarrassment of X Factor or American Idol. And it can explain how somebody would conclude that lemon juice makes their face invisible.

In short, it demonstrates the bizarre relationship between confidence and knowledge: where sometimes incompetence breeds confidence, and knowledge serves to regulate it.

Perhaps, therefore, it is apt to conclude this tale of an unwise bank robber with the words of a wise man by the name of Charles Darwin: “ignorance more frequently begets confidence than does knowledge.”

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