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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, cognitive bias refers to unfounded beliefs we may have, often without realizing it.

Keep reading to find out what the research says about the Dunning-Kruger effect, how to recognize it, and how to guard against it.

The Dunning-Kruger effect is when a person does not have skills or ability in a specific area but sees themselves as fully equipped to give opinions or carry out tasks in that field, even though objective measures or people around them may disagree. They are unaware that they do not have the necessary capabilities.

It also suggests that people with less competence in a given area are more likely to unknowingly overestimate their competence, while high performers often have a tendency to underestimate their skills and knowledge.

Experts have applied this concept to many aspects of life, from the ability to recognize faces to influencing political decisions without fully understanding the issues.

Dunning and Kruger’s original research, published in 1999, developed a common theme in psychological literature — that people’s perception of their own skill often does not match reality.

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

In the grammar study, 84 undergraduates completed a knowledge test on American Standard Written English, then rated their own grammar ability and test performance.

Those who scored the 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 tended to underestimate their ability and test score.

In a 2008 study, researchers asked students and others to assess their performance immediately after taking various tests. The results replicated those of Dunning and Kruger.

The overall results showed, on average, that:

  • People in the lower quarter in terms of performance expected to see a result of 60 percent, but they scored 38.4 percent.
  • People in the middle half expected to score 72.6 percent and scored 61.7 percent.
  • People in the upper quarter expected to score 75.6 percent and scored 84.1 percent.

The greatest overestimation was in the lower 25 percent of the class, and the greatest underestimation was in the top 25 percent.

Researchers have continued to investigate the Dunning-Kruger effect and why it happens.

Since the original study was published, various studies have produced similar results. But in recent years, some researchers have called into question the statistical model that Dunning and Kruger used. There are also criticisms that people are overusing the theory when it is not really relevant.

Some people say that, statistically, the argument does not hold up, and chance played a greater role than Dunning and Kruger allowed for. They argue that the theory is popular simply because people like to find patterns to explain why things happen.

A number of psychologists have been looking into why people sometimes think they can do more or less than they actually can.

One possible reason is the lack of skill in itself. In other words, people don’t know what they don’t know.

The second possible reason relates to a lack of insight. People are unable to see clearly what they can and cannot do because they don’t have the understanding they need to do this. This insight is known as metacognition, and it relates to knowing about knowledge.

If a person consistently overestimates their ability, they may also be more likely to reject feedback, and this can play a role in continued underperformance. If a student, for example, accepts and acts on feedback after scoring low on a test, they may do better next time.

However, those who already feel they know enough may disregard feedback because they don’t see the need. This prevents them from learning and progressing as much as they could.

In a 2021 study, researchers used electroencephalograms (EEGs), which measure brain activity, to compare the time it takes for a person to assess themselves as high or low performers. The results suggested that to reach either decision, the person uses different thought and memory processes.

Taking time to remember facts and events may produce a more accurate result than basing self-assessment on snap decisions and intuition, according to the researchers.

Dunning and Kruger investigated the performance of students to test their theory, and other researchers have found similar results in the academic field.

Here are some other areas where researchers have found significant results.

In medicine and medical training

A 2020 article discusses the impact of the Dunning-Kruger effect in graduate medical students.

Drawing on previous studies, the author notes physicians with lower competency levels tended to rate themselves higher than their performance suggested. Those who scored in the lowest 25 percent in peer assessments rated themselves 30 to 40 percent higher than others in their group.

Regarding feedback, those with lower competency levels were also more likely to reject feedback or see it as inaccurate or unhelpful.

As in other fields, awareness of their own skills and knowledge gaps is essential for healthcare professionals. Recognizing their own weaknesses will prompt them to seek professional development that will help them maintain their clinical expertise. It can also help boost self-confidence in those who might rate their skills as lower than they really are.


The Dunning-Kruger theory has proved popular in management research and development.

At work, it can lead to the following:

  • companies recruiting people who seem confident but have difficulty fulfilling their job role
  • people with limited skills and knowledge gaining promotions, while others with more expertise do not
  • difficulty responding constructively to feedback, so that performance does not improve despite guidance
  • the sharing and promotion of incorrect information

This can lead to tension and dissatisfaction in the workplace and with clients. It could also:

  • lead to errors in decision making
  • affect the prospects and performances of people reporting to a manager
  • impact the effectiveness of the overall workforce


A 2013 study asked people who identified with political parties to rate their knowledge of various social policies. Results showed that, while people expressed confidence in their own political expertise, their explanations of specific policies and ideas suggested their knowledge and understanding were limited. The Dunning-Kruger effect could at least partially explain this.

A 2017 study noted that people who analyze the least and could most benefit from questioning their beliefs also tend to have the most confidence that they are right. This is one reason political debate often seems futile, said the authors.

The author of a 2018 article further argues that people with low levels of political expertise are also more likely to align themselves with a political party. This increases their political confidence and sense of political identity. However, it effectively also allows that party to make their decisions for them. Aligning closely with a party can prevent people from thinking critically about the views they express.


Logically, only half of all drivers can be better than average. But in a 2013 study, 673 out of 909 motorists described themselves as “better than average“ drivers.

The researchers found that individual drivers tended to use their own criteria for what it means to be a “good“ driver. For example, a person may believe that their ability to run a red light without causing harm makes them a good driver.

This becomes significant if a person who believes they are an exceptional driver uses this belief as a license to take risks on the road.

In the United States, over 5.5 million accidents and over 30,000 deaths result from risky driving every year. Nurturing a more realistic view of individual driving abilities may help reduce this number.


In a survey, researchers asked 1,310 adults in the United States various questions to investigate attitudes about the link between autism and the measles, mumps, and rubella (MMR) vaccine.

Over one-third of the participants thought they knew as much or more than doctors and scientists about what causes autism. Those with low levels of knowledge showed particular confidence.

These findings suggest that the Dunning-Kruger effect may play into issues such as the decision to vaccinate children and to encourage or discourage others to do so.

Anyone can be susceptible to the Dunning-Kruger effect. It does not reflect low intelligence, but rather a lack of insight and reflection on our own abilities.

A person who is very knowledgeable in a field but lacks insight into their own performance can easily overestimate or underestimate their own ability.

A 2021 study found that those who scored high on intellectual humility were less likely to overestimate their performance in two tests. Intellectual humility is being able to accept that we may not be right about our ideas and attitudes and being open to questioning and revising them.

Reflecting on our own experience and ability and seeking feedback from others can help anyone, regardless of their educational level, form a more accurate picture of what they know and what they don’t know.

The Dunning-Kruger effect can cause us to over- or underestimate our abilities. This can affect a person’s progress and confidence in various fields.

Challenging the effect in our own lives may help us work, study, and discuss issues with those around us more effectively.

Here are some tips that may help overcome the Dunning-Kruger effect:

  • Take time to reflect. Some people feel more confident when they make decisions quickly, but snap decisions can lead to errors of judgment. Reflecting on where we went wrong last time can also help us move forward.
  • See learning as a way forward. If you are afraid to ask questions in case it reveals inadequacies, remember that no one knows everything. Asking the question or asking for help can enable you to move forward.
  • Challenge your own beliefs. Are there things about yourself or the world that you have always believed and never questioned? As the world changes, revisiting our beliefs can help us keep up with those changes.
  • Change your reasoning. Do you apply the same logic to every question or problem you encounter? Trying new approaches can help you break out of unhelpful patterns.
  • Learn from feedback. Many people feel threatened by feedback, but feedback can help us progress or improve. If you are unsure if feedback is fair, take time to reflect on your own actions and performance before deciding the other person is wrong.

Teachers can help by focusing not only on what people learn but how they learn it. By fostering a view of intelligence as malleable, they can show students that low performance can be changed through the constructive use of reflection and feedback.

The Dunning-Kruger effect is a type of cognitive bias that suggests people are not always the best evaluators of their own performance.

Everyone is prone to this effect, but curiosity, openness, and a lifelong commitment to learning can help minimize its effect.