Dunning-Kruger effect: Definition, Examples, & Facts

Have you ever wondered how objectively you assess your skills? Do you struggle with impostor syndrome or perhaps inflated self-esteem? When it comes to honestly assessing your own strengths, you cannot ignore the Dunning-Kruger effect. It refers to a type of cognitive distortion where individuals misjudge their actual abilities.

Research has shown that less competent people tend to overestimate their skills, while more skilled professionals, by contrast, underestimate their strengths.

This effect refers to a special type of cognitive distortion in which a person is convinced that they are a highly skilled expert in a given field, but actually has very limited knowledge of the subject. This psychological phenomenon often causes people to make mistakes and bad decisions. As social psychologist David Dunning famously put it, “the irony of the effect is that some people are not smart enough to admit that they are not smart enough.”

Origins

This cognitive distortion is named after American psychologists David Dunning and Justin Kruger. In 1999, they tested their students on their sense of humor, logical reasoning, and knowledge of grammar.

What set this study apart was that before showing their students the results, the psychologists first asked them to estimate their performance in terms of percentile ranking. This is where things got interesting:

• students who scored around 15% in all tests overestimated their abilities by 50% or more;
• students with the highest scores on all three tests, by contrast, significantly underestimated themselves.

But is an incompetent person able to realize that they do not have enough knowledge? To investigate this, psychologists invited test participants with the lowest scores and asked them to evaluate other participants' answers and then reassess their own performance. And this is where it became even more revealing: the lowest-scoring students not only failed to recognize their own incompetence, but also gave themselves even higher scores than they had before. They began to accurately assess their abilities only after completing training on the topics that were tested.

This effect is typically illustrated as a graph that shows the relationship between self-confidence and competence. In essence, this is the journey most people take from novice to expert. The curve consists of 4 segments:

• Peak of “Mount Stupid”. A person is extremely confident in their abilities. They think: “I know absolutely everything!” This is where you can clearly see how people with little knowledge have high self-confidence and overestimate their own competence.
• Valley of Despair. This is a completely opposite feeling compared to the previous segment of the curve: “I know absolutely nothing!”
• Slope of Enlightenment. At this stage, a person has accumulated enough practical knowledge to put to use. Now a person realizes that they have room for growth and development.
• Plateau of Sustainability. This segment indicates that the person is already an expert and has developed well-founded self-confidence.

This effect is sometimes called know-it-all syndrome. It can be spotted in casual conversation. The following signs indicate that a person is affected by this cognitive distortion:

• overestimation of their own abilities;
• underestimation of the competence of colleagues;
• a failure to recognize their own lack of skill.

That said, a person may well admit their incompetence after completing training, even if their knowledge increases only slightly.

This effect can appear in anyone. If someone's self-esteem is inflated, it may show up as:

• an overly optimistic attitude toward the results of their own work;
• a tendency to embellish their past achievements;
• “I told you so!” - insistence that a person knew exactly how an event would end;
• a tendency to behave differently in private than in professional settings;
• a strong belief that they know everything there is to know.

At work, such people can become unbearable bosses. However, more competent and less assertive people remain in the shadows.

Example 1:

In 1995, a real-life incident perfectly illustrated this effect. Two banks were robbed, but because the robbers did not disguise themselves at all, they were identified and soon arrested. The robbers had rubbed their faces with lemon juice, believing this would prevent security cameras from capturing their faces. After all, lemon juice is used as invisible ink. Before the robbery, they even tested their hypothesis by taking a Polaroid photo. But either because of defective film, or because their faces were blurred during movement, their features were unrecognizable. This finally convinced the men that they were right.

Example 2:

Have you seen the movie "Florence Foster Jenkins" (2016) with Meryl Streep? The main character Florence Foster Jenkins dreamed of becoming an opera singer. Yet she had no real singing voice and no ear for music. But the lack of talent was no obstacle to the millionaire from New York. As a result, she was widely considered the worst singer in the world, but she believed that she had an incredibly beautiful voice.

This effect is closely related to issues with self-esteem. According to psychologists, people with extremely high self-esteem are more susceptible to the Dunning-Kruger effect. You have probably met such “know-it-alls” in your life, who in fact were complete novices, compensating for their lack of knowledge with assertiveness and self-confidence.

Here you can check your self-esteem using the Rosenberg Self-Esteem Scale.

On the opposite end of the spectrum sits impostor syndrome. A person with this syndrome constantly questions their own knowledge and overestimates the knowledge and skills of others. Sometimes such individuals are so immersed in a subject that they no longer understand how far they are ahead of others. Impostor syndrome is usually accompanied by low self-esteem.

In the workplace, such people find it difficult to stand up for their views. They may defer to colleagues and management even when they know the other side is wrong. Doubts about their abilities and low self-esteem keep them from actively advocating for their ideas.

Here you can take a free Imposter Syndrome Test to find out if you are underestimating your own knowledge.

Critics of the theory often point out that the authors cherry-picked their results to fit a pre-existing theory — though the findings themselves are more easily explained by regression toward the mean. Moreover, the apparent bias would likely be less pronounced with repeated testing.

In addition, many studies show that people tend to overrate their own knowledge, and some even completely refute the Dunning-Kruger theory. For example, in a study from the University of California, 80% of unskilled respondents correctly assessed their real abilities.

Here are five tips to help you avoid falling into this trap:

• try to question your own statements — come up with counterarguments to challenge your assumption that you are right;
• learn to accept criticism;
• communicate more with other people and remain open to alternative points of view;
• do not jump to conclusions;
• calibrate your confidence — it naturally adjusts as your knowledge and experience grow.

If you are constantly working on yourself, learning something new, developing your skills, then this syndrome is not an issue for you. But keep in mind that if you are an expert in a given field, you may still be a beginner in other areas.