Dunning-Kruger Effect

January 24, 2023

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How intelligent do you think you are? Can you accurately predict your own skill level or judge the intelligence of your ideas? In 1999, David Dunning and Justin Kruger, two social psychologists, discovered that people are exceptionally poor judges of their abilities, revealing a cognitive bias that impacts almost everyone on the planet. This cognitive bias is called the Dunning-Kruger Effect.

Imagine someone sitting down to play chess for the first time. He believes he is intelligent – maybe more intelligent than average – so he assumes he can play chess better than the average person. However, chess is a complicated game that he knows almost nothing about. In other words, people have distorted perceptions of their own abilities. They fail to accurately predict their performance on a given task because they overestimate their intelligence. They are extremely confident in their abilities even though they do not know what they are doing. David Dunning and Justin Kruger found that people who know very little about a subject are more likely to overestimate their abilities, causing a large disparity between their imaged performance and actual performance. But now you may ask: why are poor-performers so confident in their abilities? Why does this cognitive bias warp our understanding of our intelligence? Well, the Dunning-Kruger Effect is often grounded in lack of self-awareness. Less intelligent people overestimate their abilities because they are unaware of what they do not know. In other words, humans become overconfident when we cannot recognise the gaps in our knowledge. 

Let’s go back to our chess player, who thinks he is a grandmaster without playing a single game of chess. He does not know what it means to play chess at a high-level. In fact, he does not understand the patterns and strategies used by great players, so he assumes he knows everything there is to know. In effect, he overvalues his natural intelligence and undervalues his lack of experience and expertise. But if you do not have experience with a subject, you cannot understand what it means to perform at a higher level. So, your perception of your abilities is muddled by your lack of experience and awareness. 

Ignorant people make the same faulty assumptions. They assume they know everything, overestimate their intelligence, and fail to recognize their shortcomings. Because they cannot identify their mistakes they cannot learn or improve. They cannot distinguish between ignorance and excellence because they do not understand what is required to achieve excellence in a given field. We call these requirements the standards of performance. They are the hurdles and challenges one must overcome to excel in any field. Some of these hurdles are things you need to learn and practice. Others are mistakes you need to understand and avoid. To paraphrase David Dunning, the skills required to succeed at a task are identical to the skills required to recognize your failures. If you cannot do one, you cannot do the other. 

Many inexperienced people do not respond well to apparent contradictions. If you present a challenging argument, their response is typically defensive or avoidant. This person is overconfident in his or her intelligence, so is convinced to have a better understanding is better than yours. Unfortunately, this is a common occurrence. Inexperienced people cannot evaluate their ideas or choices because their understanding is limited to one, very narrow, point of view. They believe what they are saying is perceptive even if others recognize the obvious flaws in their understanding. But no one likes to be wrong, especially inexperienced people. No one wants to find out that their understanding of the world is flawed. That is why narrow-minded people display an unrelenting loyalty to their opinions. This person thinks they are right because they want to be right and nothing you say is going to change their mind. But what happens when someone chooses to expand their perspective? What if someone opens their mind to new knowledge and that new knowledge changes their view of the world? Will they become more confident or less confident in their intelligence? 

David Dunning and Justin Kruger discovered that confidence decreases as people gain expertise. Ignorant people are dedicated to their ideas because they do not understand more. However, changing your perspective reveals a myriad of unknowns beyond your knowledge. Think about our chess player, who still believes he is the grandmaster. What happens when our chess player encounters a much more talented opponent, someone with a great understanding of the game? No matter how hard he tries, our chess player loses every single game. So, he reacts defensively. He criticizes the game of chess. He insults the other player until eventually he decides to open his mind. He buys a book on chess to learn more about the game. Like many curious amateurs, he begins to feel overwhelmed by the volume of information he does not understand. He was so confident in his abilities before but now he is aware of his limitations. He is beginning to understand the standards of performance. While new knowledge accelerates his understanding of the game, it also cripples his confidence. 

Just like ignorant people overestimate their abilities, intelligent people underestimate their abilities. Suddenly, you are aware of an overwhelming number of questions and mysteries. You finally recognise how challenging your field really is. Naturally, your confidence in your abilities sinks to an all-time low. Even though you are more capable than you were, you no longer value confidence over experience or expertise. You view yourself as an amateur with a lot to learn, even if you know much more than the average person. That is one reason why intelligent people underestimate their abilities, but there is one more reason. When you investigate a subject, and gain vital experience, you make another set of faulty assumptions. An inexperienced person cannot clearly observe the road ahead, but an experienced person cannot clearly see the road behind. In other words, intelligent people belittle their own expertise. You assume anyone can achieve your level of mastery. You assume the challenges you have overcome are simple or easy, no matter how difficult they really are. Return to our chess player, now he has played over a hundred games. He studied different strategies from grandmasters. In other words, he explored the depth of his field, and his perspective on the game has changed. Yet he underestimates his abilities. Even after he wins his first chess tournament, his confidence is much lower than it was at the beginning. He plays a better game of chess, but he does not accurately value his new experience or expertise. For this reason, the Dunning-Kruger Effect often graphs as an upside-down curve. On one end of the curve, expertise is low, and confidence is high. As expertise increases, confidence decreases. 

But eventually, you reach a turning point, where an intelligent person realizes how little they understand. Once you reach rock bottom, your confidence begins to increase. Your field starts to make sense. You begin to draw conclusions on your own and put complicated theories into practice. In other words, as expertise evolves into mastery, your confidence gradually increases. But note it is a different kind of confidence. The quiet confidence of a growing expert is nothing like defensive confidence at the other end of the spectrum. A growing expert only feels confidence in his abilities because he respects the difficulty of his field. He may be a leader in the industry. He may be an artist beloved by millions; yet he knows he has not learned everything there is to learn. He knows he will never have mastered his field. This mindset is what separates a confident amateur from a confident expert. Confident amateurs believe they know all there is to know. On the other hand, experts are well-aware of the gaps in their understanding. They believe in their abilities, but they know their shortcomings better than anyone.

So, what can we take away from Dunning and Kruger’s research? 

Intelligence, and our perception of our intelligence is often a paradox. We cannot know what we do not know until we know it. Often, recognising our lack of knowledge is more significant than finding actual answers. So, how do you properly judge your strengths and weaknesses? Well, the simple answer is: do not be afraid of what you do not know. Many people equate ignorance with stupidity, but they are different. An intelligent person is not afraid to admit their ignorance because ignorance can change. Questions can be answered. So, take a deeper interest in the things you believe. Make an effort to widen your perspective, and most of all keep your ego out of the equation. 


Chamorro-Premuzic, T. (2019). Why Do So Many Incompetent Men Become Leaders? Harvard Business Review Press.

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