The Dunning-Kruger Effect: How Your Level of Competence Affects Self-Confidence

by @deanyeong | Get free weekly updates here

If you’re like most people, you’re likely to be very good at something, and you openly admit that you’re less competent at something else. However, we’ve all met someone in our work and life who always overestimates their knowledge or ability of a certain topic or skill.

Worse, some people are obviously incompetent in a particular subject yet confidently insist that they know everything. That’s when you start to wonder, “How on earth could this person  be that — well — stupid?”

In fact, this is not that uncommon. Even William Shakespeare mentioned it 400+ years ago:

The fool thinks himself to be wise, while a wise man knows himself to be a fool.

Today, this phenomenon is known as a cognitive bias of illusionary superiority.

In 1999, psychologist David Dunning and his grad assistant Justin Kruger carried out an experiment and tested their hypotheses about this phenomenon. Then they coined the term,  The Dunning-Kruger Effect.

Competence VS Confidence

Dunning and Kruger examined a group of undergraduate students in several categories: the competency of writing grammatically, the ability to reason logically and a personal sense of humor.

After knowing the test scores, they asked the students to estimate their personal results. This is when Dunning and Kruger found something strange.

the dunning-kruger effect

They found that the students who were less competent had the tendency to overestimate their results, despite their test scores having placed them in the bottom percentile. Even more surprisingly, students who performed better at these tests underestimated their results .

Why Less Competent People Are More Confident

The Dunning-Kruger Effect doesn’t only happen in the academic field, it happens in almost every subject and situation. If you take a closer look, you will find them everywhere:

  • Organizations hire the most confident person during an interview, but it turns out that that person is also the least capable one.
  • Celebrities who think they’re smart become the spotlight while scientists who made world-changing discoveries get no media attention.
  • Your friend who claims to be good driver or a great chess player is usually the least skilled one.

The pressing question is: Why are the least competent people usually the most confident ones?

The least skilled person often overestimates their ability because they have no idea how much they don’t know. In other words, poor performers believe they know everything in a particular subject and therefore they tend to be overconfident about it.

Real knowledge is to know the extent of one’s ignorance. — Confucius.

On the other hand, high performers are fully aware of the vastness and complexity of the field they’re working in. They know how much they don’t know, and thus, they usually underestimate their ability and competence in a particular area.

In contrast to high performers, poor performers also do not learn from feedback suggesting a need to improve. Again, this is because they already believe they know everything.

Metacognition: Thinking about Thinking

The Dunning-Kruger Effect also has to do with what scientists call Metacognition.

Metacognition is “cognition about cognition”, “thinking about thinking”, and “knowing about knowing”. It’s the highest form of cognition – which is to be aware of the awareness itself.

A person with a high level of metacognition is able to become aware of his or her thought processes and view them from a fresh perspective. This allows them to analyze and judge their ideas, knowledge, and skills more accurately compared to people who are having difficulties with Metacognition.

In the book Self-Insight by David Dunning, he stated that:

“If you’re incompetent, you can’t know you’re incompetent… The skills you need to produce a right answer are exactly the skills you need to recognize what a right answer is.”

As it turns out, people who fall prey to the Dunning-Kruger Effect — those who are overconfident and who overestimate their competence — usually have a lower ability of Metacognition.

How to overcome the Dunning-Kruger Effect

In reality, the Dunning-Kruger Effect isn’t a joke for smart people. Instead, it’s a cognitive bias that negatively impacts our society from the individual to the organizational level.

Incompetent people rise to the top in all kinds of organizations because they’re more confident while real talent gets buried due to self-doubt.

One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision. – Bertrand Russell

And here are a few suggestions I have to overcome this cognitive bias.


When hiring a new employee and seeking a business partner (or even getting into a relationship), evaluate the candidate with multiple measurable parameters. Don’t just take his or her word for everything. Instead, test the candidate with real tasks and assess for yourself.


Instead of evaluating your performance by looking into your mind, look back into your life. This technique is useful for both people who are overconfident or for those who have self-doubt. With retrospection, you’re measuring yourself up against you past record and performance.


In the Dunning experiment, incompetent students improved the ability to correctly estimate their test results after receiving minimal tutoring on the skills they lacked. Regardless of which category you are in, it’s helpful to have someone who is ahead of you show you what you have yet to learn.

The Complexity of The Human Mind

The more we study something, the less we know about it.

It’s a beautiful paradox that only people who really dig deep into what they’re learning can experience. On the other hand, people who dabble on the surface of anything they pursue will never know how much they still have to learn.

In the process of writing this piece, I have realized that there are no end destinations in learning, in mastering a skill, or in gaining wisdom of any kind.

In almost all forms of learning and practicing — creative, sports, entrepreneurship — the focus should never be on the end results.

But on the process.