Dunning-Kruger effect (A complete guide)

The Dunning-Kruger Effect manifests in people who think they are really great when they are really not.

What is the Dunning-Kruger effect?

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The Dunning-Kruger effect is a type of cognitive bias in which people believe that they are cleverer and more capable than they really are. The combination of poor self-awareness and low cognitive ability leads them to overestimate their own capabilities. If often manifests in self-proclaimed experts, who overplay their own level of skill while failing to recognize genuine skill in others.

People overplay their own level of skill while failing to recognize genuine skill in others.

There is another concept or term used in behavioral psychology, different than Dunning-Kruger effect. It is called Thorndike Law of Effect.

Where does the term Dunning-Kruger originate?

The effect was first outlined in a 1999 paper by two Cornell psychologists; Justin Kruger and David Dunning. The Dunning and Kruger experiments tested participants in areas of grammar, humor and logic and compared the student’s actual results with each participant’s judgment of how well they did in the tests.

For example, the humor experiment consisted of participants being given a suite of jokes and asked to rate how funny they were on a scale of 1–11. The ratings were then compared to the “funny” ratings of eight professional comedians. One key aspect of the experiment is that the participants did not know about the professional comedian contribution. As one last question, participants were asked to estimate how good they were at recognizing something as funny compared with a typical Cornell student.

The participants who were the worst at judging whether a joke was funny (when compared with the comedians) thought they were above average at the task. For example, people with test scores in the 12th percentile estimated themselves to be in the 62nd percentile. On the other hand, participants who did really well on the task thought they were a little worse than they really were.

The other tasks used US standard Law Society Admission Test (LSAT)  questions to represent logic, along with a National Teacher Examination prep book. Both tasks were designed to introduce a more levelling factor. But the results always remained the same. People continually rated themselves just about average or above, even when they scored terribly.

What is the basic premise of the Dunning-Kruger effect?

The less competent you are at something, either socially or intellectually, the more confident you are in your abilities in that area. This overestimation occurs, in part, because people who are unskilled or incompetent in the approaches they adopt to achieve success and satisfaction suffer two major problems. Not only do they make bad choices and therefore reach the wrong conclusions, but their incompetence robs them of the ability to realize their incompetence. Instead, they are left with the mistaken impression that they are doing just fine.

In simple terms: What you don’t know can hurt you because, when you do the wrong thing, you won’t know it.

What can we learn from the Dunning-Kruger experiment?

The Dunning-Kruger experiment further supports another well-known psychological basis, which proposes that most people tend to overestimate their capabilities. People will rate themselves as average or above average on essentially all tasks. If you understand how averages work you know this is impossible (some people have to be below average, some are average, and some are above average for the whole thing to work).

One puzzling aspect of the results is how the incompetent fail, through life experience, to learn that they are unskilled. If a person keeps repeating mistakes and getting things wrong, it would seem logical to assume that they would learn and improve. 

One reason not, is that people rarely receive negative feedback about their skills and abilities from others in everyday life. This could be seen as tact, diplomacy or respect, but the end result is the same. Most people do not like telling other people that they have messed up. However, conversely, what the Dunning-Kruger effect teaches us is that people really do need honest feedback in order to learn.

Professor Dunning himself notes the irony of the Dunning-Kruger effect “the knowledge and intelligence that are required to be good at a task are often the same qualities needed to recognize that one is not good at that task—and if one lacks such knowledge and intelligence, one remains ignorant that one is not good at that task.”

As Charles Darwin wrote in The Descent of Man that “Obliviousness more regularly sires certainty than does knowledge”.

What causes the Dunning-Kruger effect?

It could be argued that some people are simply too stupid to know how dense they are. Dunning and Kruger proposed that this phenomenon originates from what they call a “dual burden.” People are not just incompetent; their incompetence denies them mental ability to realize just how poorly skilled they are. 

Incompetent people tend to: 

• overestimate their own abilities

• fail to recognize the genuine skill and levels of expertise of other people 

• fail to recognize their own errors and lack of ability.

Incompetent people tend to fail to recognize the expertise of other people.

Dunning noted that the very knowledge and skills necessary to be good at a task are the exact same qualities that a person needs to recognize that they are not good at that task. So if a person lacks those abilities, they not only stay bad at that task, but are unaware of their own inability.

People are often only able to evaluate themselves from their own limited and highly subjective point of view. From this limited perspective, they seem highly skilled, knowledgeable, and superior to others. Because of this, people sometimes struggle to have a more realistic view of their own abilities.

Who is affected by the Dunning-Kruger effect? 

The fact is that we all are susceptible to this effect, to varying degrees. Actually, most of us probably experience it with surprising regularity. People who are genuine experts in one area may mistakenly believe that their intelligence and knowledge mean they are also above average in other areas in which they are less familiar. A genius scientist, for example, might be a very poor writer. In order for the scientist to recognize this, they would need to possess a good working knowledge of spelling, grammar and composition. With these lacking, this particular scientist also lacks the ability to recognize their own lack.

It is interesting to ponder what genuine experts think of their own abilities? Dunning and Kruger found that those at the high end of the competence spectrum did hold more realistic views of their own knowledge and capabilities. However, these experts actually, and ironically, tended to underestimate their own abilities relative to how others did.

Can the Dunning-Kruger effect be controlled? 

We are all susceptible to manifesting the Dunning-Kruger effect. Becoming more familiar with how the brain works and the mistakes we are all capable of making may be a step forwards on the road to shedding these habits. To understand one’s own skills and limitations a little better we can all:

• Keep learning and practicing: With deeper knowledge comes sharper recognition of how much is still to learn. 

• Ask others how you’re doing: Constructive criticism is a powerful thing, if you can take it and turn it into a positive outcome.

• Question what you know: Keep challenging your beliefs and knowledge base. Dig information that challenges your thoughts rather than confirms them.

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Frequently asked questions (FAQs) about the Dunning-Kruger effect: 

1. Do you suffer from the Dunning Kruger effect?

Do you tend to overestimate your own level of skill in some areas? Do you fail to recognize genuine skill in others? Do you fail to recognize the extent of your inadequacy in certain subjects? Then yes, you probably suffer from this effect. Most of us do at some point or other.

2. How do you overcome the Dunning Kruger effect?

The problem is that we don’t know what we don’t know. Try comparing your performance against your own previous performance rather than against a peer group. This way you can see if you are improving and learning. Also, focus on very specific tasks rather than general abilities e.g. you can fill your windscreen wash but this does not mean you are a skilled car mechanic. Thirdly, seek out and listen to established experts

3. Why is the Dunning Kruger effect important?

It is important to realize when this trait is manifesting in others, so as to accept it for what it is and not misunderstand where the person is coming from. The workplace is a key location – where many people will blame a computer for being ‘moody’ or their colleagues for giving them bad information, rather than recognize their own inability to implement macros in an Excel spreadsheet. It is not that they are pretending and finding excuses, with Dunning Kruger they genuinely will not realise it is their own shortcoming.

DKE is prevalent at work, where people often blame tools or colleagues while not recognizing their own shortcomings

What is the opposite of Dunning Kruger?

There is an effect called ‘imposter syndrome’, where genuine high achievers believe they have somehow tricked people into thinking they are brilliant. They attribute their success to luck, rather than their own high-value ability.

5. What is a person who thinks they are always right?

Usually a highly controlling person who lacks the interpersonal sensitivity to realise that they are coming across that way. But they probably feel they have fantastic interpersonal sensitivity, ironically

6. How do you deal with someone who thinks they’re always right in decisions?

Do not assume a particular personality disorder, after all, you are (probably) not the expert in this field either! Recognize that in some part the person is displaying low emotional intelligence, try not to get angry, and try hard to keep the lines of communication open, while maintaining your own integrity.

Dunning-Kruger effect (A complete guide)

Want to learn more about the Dunning-Kruger effect? Try these books!

The Death of Expertise: The Campaign against Established Knowledge and Why it Matters 

Today, everyone knows everything – with a quick trip through WebMD or Wikipedia, average citizens believe themselves to be on an equal intellectual footing with doctors and diplomats. All voices, even the most ridiculous, demand to be taken with equal seriousness, and any claim to the contrary is dismissed as undemocratic elitism. Tom Nichols’ The Death of Expertise shows how this rejection of experts has occurred: the openness of the internet, the emergence of a customer service model in higher education, and the transformation of the news industry into a 24-hour entertainment machine, among other reasons. Paradoxically, the increasingly democratic dissemination of information, rather than producing an educated public, has instead created an army of ill-informed and angry citizens who denounce intellectual achievement.

The Little Book of Stupidity: How We Lie to Ourselves and Don’t Believe Others Kindle Edition

Best-selling author, Sia Mohajer, takes us on a journey through the statistics, experiments and psychology of stupidity to reveal one important fact – self-delusions are part of being human.


Unskilled and unaware of it – by Kruger and Dunning, 1999

When You Know Nothing but Think You Know Everything – psychologytoday.com by Adi Jaffe Ph.D

The Dunning-Kruger Effect – verywellmind.com, June 2019

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