We all know someone who thinks they’re smarter than they are. But before you judge, you’d better check you are free from the Dunning Kruger Effect.

The theory of this effect was developed by David Dunning and Justin Kruger of Cornell University. They found that this cognitive bias occurs when people fail to adequately assess their level of competence — or incompetence — at a task and consider themselves to be more competent than they actually are.

The theory is also commonly known as ‘Mount Stupid‘. According to the Urban Dictionary, Mount Stupid is ‘the place where you have enough knowledge of a subject to be vocal about it, without the wisdom to gather the full facts or read around the topic‘.

However, the  Dunning Kruger Effect has been thoroughly studied by psychologists and is no armchair theory or pop psychology topic.

What is the Dunning Kruger Effect?

This psychological bias, where a person believes themselves to be smarter and more competent than they actually are, was first identified in Kruger and Dunning’s 1999 study “Unskilled and Unaware of It: How Difficulties in Recognizing One’s Own Incompetence Lead to Inflated Self-Assessments“.

In essence, it shows how people with low ability do not have the necessary critical ability and self-awareness to recognize how low their ability actually is. This leads to them having a superior view of their own competence and knowledge.

In simple words, it is “when people are too stupid to know how stupid they are”.

How did Dunning and Kruger test the hypothesis?

David Dunning and Justin Kruger developed their theory by having participants undergo tests of humor, logic, science and grammar. They found that those who performed best at the tasks consistently underestimated their ability. Conversely, those who performed worst believed that they had in fact done well. They found that in every area they tested, as cognitive ability worsens, so does the ability for the participant to accurately assess their ability.

In one particular experiment, the pair asked participants if they were familiar with certain technical scientific concepts. The trick was that some terms were completely made up. They found that,

“A fair number claim familiarity with genuine terms like centripetal force and photon. But interestingly, they also claim some familiarity with concepts that are entirely made up, such as the plates of parallaxultra-lipid, and cholarine”.

What were their findings?

Dunning and Kruger found that the most dangerous situation is when people have some knowledge about a subject rather than when they know nothing about it.

This idea is something that we have been aware of for generations. The phrase “A little knowledge is a dangerous thing“, is widely attributed to Alexander Pope who wrote it in  ‘An Essay on Criticism‘, in 1709. As the humorist Josh Billings said “It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.”

Unfortunately, there is no easy solution to the problem. Dunning pointed out that “for poor performers to recognize their ineptitude would require them to possess the very expertise they lack“.

Interestingly, Dunning and Kruger showed that as you begin to learn more about a subject or become more skilled at a task, you begin to rate your ability less favorably. You become aware of all that you do not know about a subject. This is a completely different cognitive bias known as ‘Imposter Syndrome’.

How the Dunning Kruger effect can be dangerous

While it can be quite funny to see someone make a fool of themselves, the Dunning Kruger effect can actually be dangerous.

For example, doctors have found that elderly people refuse to exercise to relieve pain, even though this is the most effective method of pain treatment. This is because they mistakenly believe that the physical discomfort they feel after exercising is a sign that they have made the condition worse.

In an even more serious example, mothers in India sometimes withhold water from infants suffering from diarrhoea because they believe too much water is what is causing the condition.

In economic situations, the repercussions of the bias are also serious. Studies have suggested that the 2008 meltdown was caused by overconfident financiers and consumers who weren’t as financially literate as they thought they were.

Closing thoughts

Of course, it is very difficult to know that you don’t know something. For example, if you don’t know the rules of grammar, how can you possibly perceive that you have broken them?

We probably all have areas where we think we understand more than we do, or we think we are more skilled at something than we actually are. But perhaps we should check our facts before we voice our opinions, just in case.


  1. psmag.com
  2. psycnet.apa.org

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This Post Has 4 Comments

  1. Joe Bloggs

    Stupid People, Think That They are Smart?

  2. Carlos

    Always so wise, indeed!!!!!!!!!!!!

  3. Eddie

    It takes two to know two. lol

  4. swinney

    Just to be clear, D-K never compared smart and stupid people. The study of *university undergraduates* (not stupid people) showed some tendency of students at the lower end of the university spectrum to overestimate their performance *relative to their classmates*. (Students from higher social class backgrounds were more likely to overestimate their performance.)

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