The Dunning-Kruger Effect

Medically Reviewed by Jabeen Begum, MD on February 07, 2024
Written by Shishira Sreenivas, Shawna Seed
7 min read

The Dunning-Kruger effect happens when when someone who isn't especially knowledgeable in a particular area overestimates how much they know or how good they are at an activity. 

This faulty perception is a type of what psychologists call cognitive bias.

The Dunning-Kruger effect was named after two Cornell University psychologists, David Dunning, PhD, and Justin Kruger, PhD. They coined the term in a paper on their observations of this behavior in 1999.

Cognitive bias is an umbrella term used to describe a reasoning error or flaws in judgement. Your brain may overlook basic things like logic, strategy, and probability. Think of it like a blind spot as you navigate your day-to-day life. Cognitive bias can create gaps in knowledge that go on to affect how you make decisions. This then shapes how you understand the world around you.

Anyone and everyone can have cognitive biases. In fact, most people are unaware they have certain biases ingrained in them. Basically, people with this type don't know that they are ignorant of their own ignorance.

Over time, this bias-based decision-making can have short- and long-term consequences. It can bleed into important parts of your life, like relationships and work. It may even affect your general world view.

To observe this phenomenon, Dunning and Kruger gave students tests of grammar, logical reasoning, and humor. The psychologists found that those who scored in the bottom 25% tended to overestimate their ability and test score. Most predicted their scores to be above the 60th percentile.

On the other hand, those who overperformed--those in the top 25% of the students--also incorrectly assessed their final result. Most of these students estimated their scores to be in the 70th to 75th percentile range. But most actually scored above the 87th percentile. Although this is also not a realistic self-assessment, the researchers found that this group was competent enough to understand how they got a higher score, unlike the low performers. In other words, the gap between perceived and actual performance is smaller.

Dunning-Kruger Curve

The Dunning-Kruger effect is also called the Dunning-Kruger Curve. 

An inexperienced person might start with high confidence that doesn't match their knowledge or abilities. As they learn more, they understand their shortcomings, and their confidence drops even though their knowledge has increased. As they gain more knowledge and experience, their confidence rebounds, but it's never as high as it was in the beginning. 

Scientists have continued to research the Dunning-Kruger effect. Some studies reinforced the findings, and others have suggested that the effect shown in the 1999 paper might merely reflect how statistics work. Some suggest that the effect, while real, is not as big as it appeared in the study.

So, what makes some people convinced they're more qualified or knowledgeable than they really are? In the original study, Dunning and Kruger say they pinpointed two major things that are directly responsible for causing this particular bias.

They are:

Incompetence in a given field or topic. This is the lack of skill or knowledge required to do things that result in the best possible outcome.

Lack of metacognition. Simply put, metacognition is the ability to think about thinking. People with this bias lack the basic knowledge and insight required to realize whether a decision, an opinion, or a belief is correct or not.

Other researchers have suggested further causes. They include: 

  • Intuition vs. analytic thinking. People who rely more on their intuition may not have the data to understand that their intuition is wrong, and people who rely more on data are analytical enough to recognize the possibility they could be wrong. 
  • Wanting to make decisions quickly, people fall back on familiar thinking patterns instead of processing new information.
  • Anchoring, a process where people establish a benchmark in their minds for how they think they'll do, and then don't update that benchmark with newer, relevant information about their knowledge and abilities.

The effect doesn’t happen only to people with a lack of skills or level of education. It can happen to anyone. You may spot the Dunning-Kruger effect among people who:

  • Are poor performers
  • Are overconfident
  • Lack appropriate skills
  • Lack knowledge
  • Lack the ability to be self-aware

Studies have observed the Dunning-Kruger effect among:

  • College undergraduate students completing an exam
  • Medical students and their ability to self-assess interviewing skills
  • Clerks on their job performance
  • Medical lab technicians on their job expertise and skills

 

The Dunning-Kruger effect phenomenon isn't limited to labs and studies. You can see it--and its consequences--almost everywhere in the real world.

This includes:

Work

At work, everyone can be prone to overestimating their ability to perform well at their job. But showing too much overconfidence without the necessary evidence to back it up could make it hard to manage expectations among your co-workers and managers.

The Dunning-Kruger effect can affect many parts of the work environment.

This includes:

  • Recruiting candidates who seem confident but, in reality, are unqualified for the position
  • Tension and conflict that create a toxic environment

To combat this, managers often hold yearly and semiannual performance reviews to give employees feedback on their work ethic and the quality of their work.

Politics

The Dunning-Kruger effect can have an impact on your knowledge of politics and current affairs. One recent study took a look at its effects on political knowledge and discussion.

The study found that people with little to no knowledge of policy may voice strong opinions. These opinions could have short- and long-term real-life consequences within society.

Some examples include when you see people:

  • Sharing political opinions as facts on social media 
  • Resisting any counterarguments that may not align with their political beliefs
  • Assessing others' political knowledge based on their own ideas and beliefs
  • Believing stereotypes about those who don't have the same political beliefs
  • Being unwilling to listen or discuss politics with actual political experts
  • Holding strong political biases or doubling down on them, especially when they engage with people who don't share the same views
  • Spreading misinformation that can have dangerous consequences

The study notes that there needs to be more in-depth research done on the Dunning-Kruger effect and its role in politics.

Health

One study that looked at how well people understood their health found the Dunning-Kruger effect: Those with the lowest "health literacy" rated themselves as knowledgeable. That can lead to people choosing unhealthy or risky behaviors while believing they are taking good care of themselves. Several studies have shown that people who refuse vaccinations overestimate their knowledge about vaccine safety.

Education

Students who are overconfident about how well they know material may underestimate how much they need to study for exams.

Social relationships

Studies looking at racist and sexist attitudes found that people overestimate how fair their views are. The more prejudiced a person was, the more fair they believed themselves to be.

The Dunning-Kruger effect is an unconscious cognitive bias. Most people don’t realize their overconfidence or their overestimation of their skills. This makes it hard to overcome. But it can start with conscious training to improve self-reflection and curb biases.

Here are some tips to overcome your own bias:

  • Understand the nature of your bias. Try to recognize and categorize probable biases. This will allow you to approach your biases in a more open and informed way.
  • Work on improving self-awareness. There are several evidence-based tests available to help you weed out any unconscious biases you may be holding.
  • Share and discuss your biases with others. Lack of skill or knowledge may stop you from recognizing your own limits. But others around you can help point them out and give you a new perspective--one you may have missed otherwise.
  • Be open to criticism. This is key if you're aiming to overcome an unconscious bias. It can help you improve on any reasoning errors or flaws in judgment moving forward.

 

The Dunning-Kurger effect was first identified by researchers at Cornell University. They found that low performers on a test overestimated how well they'd done, and high performers underestimated their own success. It's a type of something called cognitive bias, and it can happen to anyone. The effect can have an impact at work, in politics, at school, and on your health. The best way to avoid it is to try to recognize your own biases and be more self-aware.

Is the Dunning-Kruger effect real?

Since Cornell University researchers first named it in 1999, numerous other studies have looked at the concept. Some have cast doubt on the concept, or suggested it's not as big as reported. But studies have found the Dunning-Kruger effect in many areas: among medical students, college students, and in attitudes about politics and health. 

What are the four stages of the Dunning-Kruger effect?

The four stages describe not the effect itself, but four stages of learning any skill or new information. They are: 

  • Unconscious incompetence, when you don't know what you don't know 
  • Conscious incompetence, when you're aware of what you don't know but haven't yet learned it 
  • Conscious competence, when you're gaining knowledge 
  • Unconscious competence, when you've mastered something 

Is the Dunning-Kruger effect good or bad?

If you overestimate your knowledge and abilities, you may run into problems at work or school. The Dunning-Kruger effect can also affect your health, politics, and relationships with others.