Dunning-Kruger Effect: You can’t know what you don’t know!


You get assigned a group for a school project. You are working with Jimmy, a stubborn classmate who loves to argue. While you have spent hours researching your topic, Jimmy hasn’t done anything to prepare. But, when you sit down to write the paper, Jimmy claims that your definition is wrong, and that he is right. He also claims that he knows the most about this topic of everyone in your group, despite his lack of actual knowledge. Most of us have experienced a frustrating encounter like this before.

Here’s Why

This situation often occurs because the least skilled people tend to lack a sense of self-awareness. Even though they may have very little knowledge on a topic, they believe they are more competent than they are. 

When studying the Dunning-Kruger effect it is helpful to think about it as a double curse of incompetence. People that lack knowledge in a certain area arrive at incorrect conclusions, and are not smart enough to see their mistakes and correct them. Our brains want to believe we are super knowledgeable and superior to those around us, but oftentimes, we may not be.


The Dunning-Kruger effect is a cognitive bias in which the least skilled people tend to overestimate their abilities and knowledge. This phenomenon results when people lack intellectual humility, an awareness of the limitations of one’s reasoning abilities, and one’s biases. The Dunning-Kruger effect can also be linked to a hiccup in metacognition, which is the idea of actively thinking about one’s thoughts and analyzing them. 

The History

In 1999, two Cornell psychologists, David Dunning and Justin Kruger, wrote the first paper describing the Dunning-Kruger effect based on their research. In their study, they asked four groups of adults to complete certain tests in three subjects: logic, grammar, and sense of humor. They also asked participants to rate their level of skill on a percentile scale on these subjects before seeing their actual scores. Their findings confirmed their hypothesis that the least skilled participants would have a heightened perception of their performance. More specifically, people who scored in the 12th percentile assumed that they would be in the 62nd percentile, a significant overestimate.

To further understand why this was occurring, Dunning and Kruger asked the lowest-scoring and highest-scoring participants to grade other people’s tests and then allowed them to rank themselves once again in relation to all the participants. While the assumption was that they would realize they performed in a much lower percentile, the participants just kept inflating their initial scores. These studies verified Dunning and Kruger’s hypothesis that incompetent participants would not be able to accurately evaluate their level of competence.

Why Care?

The Dunning-Kruger effect is present in many domains of life. Even after the research conducted by Dunning and Kruger, psychologists are still trying to understand the impact of it in the real world. Later research on the effect demonstrates the impact of this bias in America. For example, a study published in 2018 shows that Americans who knew very little about politics and government tended to overestimate their knowledge in this field. They also found that the effect was more prevalent among individuals who identified with a political party. The Dunning-Kruger effect can be dangerous, as it causes people to feel overconfident about things they may know little about. 

So, you’re probably asking yourself: what can we do to prevent the Dunning-Kruger effect? The key to avoiding this bias is awareness. According to David Dunning, you can be self-aware by being your own devil’s advocate and constantly challenging your own beliefs. He claimed that we should strive to be “good at knowing what we don’t know”.

Think Further

  1. How have you noticed the Dunning-Kruger effect in your own life?
  2. What steps are you going to take to avoid the Dunning-Kruger effect in the future?
  3. If you were a researcher, what kind of study would you conduct to see the impact of the Dunning-Kruger effect?

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Learn More

  1. Network, The Learning. “The Dunning-Kruger Effect: Why Incompetence Begets Confidence.” The New York Times, The New York Times, 7 May 2020, www.nytimes.com/2020/05/07/learning/the-dunning-kruger-effect-why-incompetence-begets-confidence.html.
  2. “Dunning-Kruger Effect.” Psychology Today, Sussex Publishers, www.psychologytoday.com/us/basics/dunning-kruger-effect.
  3. Cherry, Kendra. “How Cognitive Biases Influence How You Think and Act.” Verywell Mind, 5 May 2020, www.verywellmind.com/what-is-a-cognitive-bias-2794963#:~:text=A cognitive bias is a,and judgments that they make.
  4. Duignan, Brian. “Dunning-Kruger Effect.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 26 July 2019, www.britannica.com/science/Dunning-Kruger-effect.