Named after psychologists David Dunning and Justin Kruger, the Dunning-Kruger effect is a type of cognitive bias that causes people to overestimate their knowledge or ability, particularly in areas with which they have little to no experience.

In psychology, the term “cognitive bias” refers to unfounded beliefs that many of us have, often without realizing it. Cognitive biases are like blind spots.

Keep reading to find out more about the Dunning-Kruger effect, including everyday examples and how to recognize it in your own life.

What is the Dunning-Kruger effect?

The Dunning-Kruger effect suggests that when we don’t know something, we aren’t aware of our own lack of knowledge. In other words, we don’t know what we don’t know.

Think about it. If you’ve never studied chemistry or flown a plane or built a house, how can you accurately identify what you don’t know about that topic?

This concept might sound familiar, even if you’ve never heard the names Dunning or Kruger. Indeed, the following popular quotes suggest that this idea has been around for some time:

Quotes about knowledge

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

  • “Ignorance more frequently begets confidence than does knowledge.” — Charles Darwin

  • “The more you learn, the more you realize you don’t know.” — Unknown

  • “A little learning is a dangerous thing.” — Alexander Pope

  • “The fool doth think he is wise, but the wise man knows himself to be a fool.” — William Shakespeare

Simply put, we need to have at least some knowledge of a topic to be able to accurately identify what we don’t know.

But Dunning and Kruger take these ideas one step further, suggesting that the less competent we are in a given area, the more likely we are to unknowingly exaggerate our own competence.

The keyword here is “unknowingly.” Those affected aren’t aware that they’re overestimating their own ability.

Examples of the Dunning-Kruger effect


At work, the Dunning-Kruger effect can make it difficult for people to recognize and correct their own poor performance.

That’s why employers conduct performance reviews, but not all employees are receptive to constructive criticism.

It’s tempting to reach for an excuse — the reviewer doesn’t like you, for instance — as opposed to recognizing and correcting failings you aren’t aware you had.


Supporters of opposing political parties often hold radically different views. A 2013 study asked political partisans to rate their knowledge of various social policies. The researchers found that people tended to express confidence in their own political expertise.

Their explanations of specific policies and these ideas later revealed how little they actually knew, which could be explained at least in part by the Dunning-Kruger effect.


Are you ever overly optimistic when planning your day? Many of us make plans to maximize productivity, and then find we can’t accomplish all we’ve set out to do.

This might be partially due to the Dunning-Kruger effect, in which we believe we’re better at certain tasks and can therefore accomplish them faster than we actually can.

About the research

Dunning and Kruger’s original research was published in the Journal of Personality and Social Psychology in 1999.

Their research involved four studies assessing participants’ actual and perceived abilities in humor, logical reasoning, and English grammar.

In the grammar study, for instance, 84 Cornell undergraduates were asked to complete a test evaluating their knowledge of American Standard Written English (ASWE). They were then asked to rate their own grammar ability and test performance.

Those who scored lowest on the test (10th percentile) tended to drastically overestimate both their perceived grammar ability (67th percentile) and test score (61st percentile).

In contrast, those who scored highest on the test tended to underestimate their ability and test score.

In the decades since this study was published, numerous other studies have reproduced similar results.

The Dunning-Kruger effect has been documented in domains ranging from emotional intelligence and second-language acquisition to wine knowledge and the anti-vaccination movement.

Causes of the Dunning-Kruger effect

Why do people overestimate their own abilities?

In a 2011 chapter from Advances in Social Experimental Psychology, Dunning proposes a “double burden” associated with low expertise in a given subject.

Without expertise, it’s hard to perform well. And it’s hard to know you’re not performing well unless you have expertise.

Imagine taking a multiple-choice test on a topic you know next to nothing about. You read the questions and choose the answer that seems the most reasonable.

How can you determine which of your answers are correct? Without the knowledge required to choose the correct answer, you can’t evaluate how accurate your responses are.

Psychologists call the ability to evaluate knowledge — and gaps in knowledge — metacognition. In general, people who are knowledgeable in a given domain have better metacognitive ability than people who aren’t knowledgeable in that domain.

How to recognize it

Our brains are hardwired to look for patterns and take shortcuts, which help us to quickly process information and make decisions. Often, these same patterns and shortcuts lead to biases.

Most people have no trouble recognizing these biases — including the Dunning-Kruger effect — in their friends, family members, and co-workers.

But the truth is that the Dunning-Kruger effect affects everyone, including you. No one can claim expertise in every domain. You might be an expert in a number of areas and still have significant knowledge gaps in other areas.

Moreover, the Dunning-Kruger effect isn’t a sign of low intelligence. Smart people also experience this phenomenon.

The first step to recognizing this effect is something you’re already doing. Learning more about the Dunning-Kruger effect can help you pinpoint when it might be at work in your own life.

Overcoming the Dunning-Kruger effect

In their 1999 study, Dunning and Kruger found that training enabled participants to more accurately recognize their ability and performance. In other words, learning more about a particular topic can help you identify what you don’t know.

Here are a few other tips to apply when you think the Dunning-Kruger effect is at play:

Take your time. People tend to feel more confident when they make decisions quickly. If you want to avoid the Dunning-Kruger effect, stop and take the time to investigate snap decisions.

Challenge your own claims. Do you have assumptions you tend to take for granted? Don’t rely on your gut to tell you what’s right or wrong. Play devil’s advocate with yourself: Can you come up with a counter argument or rebuttal to your own ideas?

Change your reasoning. Do you apply the same logic to every question or problem you encounter? Trying new things can help you break out of patterns that will increase your confidence but decrease your metacognition.

Learn to take criticism. At work, take criticism seriously. Investigate claims that you don’t agree with by asking for evidence or examples of how you can improve.

Question longstanding views about yourself. Have you always considered yourself a great listener? Or good at math? The Dunning-Kruger effect suggests you should be critical when it comes to assessing what you’re good at.

Be open to learning new things. Curiosity and continuing to learn may be the best ways to approach a given task, topic, or concept and avoid biases like the Dunning-Kruger effect.

The takeaway

The Dunning-Kruger effect is a type of cognitive bias that suggests we’re poor evaluators of gaps in our own knowledge.

Everyone experiences it at some point or another. Curiosity, openness, and a lifelong commitment to learning can help you minimize the effects of Dunning-Kruger in your everyday life.

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Medically reviewed by Timothy J. Legg, Ph.D., CRNP — Written by Carly Vandergriendt on May 15, 2020