Why incompetent people fail to recognize their incompetency.


Dunning–Kruger Effect

, explained.

What is the Dunning–Kruger Effect?

A common reading of the Dunning–Kruger Effect is that those people who are least competent at a task often incorrectly rate themselves as high-performers because they are too ignorant to know otherwise.

What it is

The Dunning-Kruger effect is a cognitive bias in which individuals are prone to assess their cognitive ability as greater than it truly is. Most simply, individuals who are the least competent at a task often incorrectly rate themselves as high-performing even when they lack particular knowledge or expertise.

The Dunning-Kruger effect is related to the cognitive bias of illusory superiority and comes from the inability of people to recognize their lack of knowledge or ability. In turn, these individuals will lack the ability to recognize their own mistakes and errors, making them exceptionally confident and biased self-evaluators. They are also unable to fairly judge other people’s performance.

This bias was first described by social psychologists David Dunning and Justin Kruger in 1999.  Dunning and Kruger found the bias by testing students in the areas of humor, grammar, and logic. They compared each individual student’s test results with the same student’s estimate of how well they scored. The results were that those who scored the lowest vastly overestimated their scores, while those who did best slightly underestimated their performance. It is illustrated in the graph below which shows those who have almost zero knowledge on a topic display low confidence, but those with a minimum level of competence vastly overestimate their abilities. As the level of knowledge increases, those who are more competent are more aware of the gaps in their knowledge and display lower confidence. On the far end of the spectrum are experts in a particular field who display a high degree of confidence. 


The fool doth think he is wise, but the wise man knows himself to be a fool.”—William Shakespeare Touchstone, in As You Like It .

A little knowledge is a dangerous thing” wrote the poet Alexander Pope in An Essay on Criticism, 1709.

Charles Darwin said, “Ignorance more frequently begets confidence than does knowledge”- in The Descent of Man in 1871


Dunning-Kruger Effect

Source: William Poundstone

In another study Ehrlinger et al. (2008) examined students in a collegiate debate tournament. They found that students performing in the lowest 25% greatly overestimated their skills. In fact,  they guessed they’d won almost 60% of their matches when in reality they had won around 22%. The lowest performers weren’t simply overcompensating for a lack of skill or boosting their confidence to hide their insecurities. Instead, they were genuinely unaware of their incompetence. The results showed that the debaters performing in the lowest 25% had the least knowledge of debating, so they were unable to accurately judge their own performance.

In short,  individuals who are the least competent at a task often incorrectly rate themselves as high-performing even when they lack particular knowledge or expertise.

Two Key Reasons Why this Bias Exists:

  1. Ego – We tend to overestimate our abilities and knowledge on various topics as a way to increase our confidence. We do not want to plead ignorance to others or ourselves. In turn, our minds create a natural defense to respond to these situations (Ehrlinger et al., 2008).
  2. Knowledge Gaps – our below-average abilities in an area inherently makes us a bad judge of how good we are in that skill. Therefore, having knowledge gaps makes it difficult for us to detect our own errors. Imagine trying to identify a well-written piece if you yourself do not possess solid grammar skills. (Dunning & Kruger, 1999).
“ Overestimation occurs, in part, because people who are unskilled in these domains suffer a dual burden: Not only do these people reach erroneous conclusions and make unfortunate choices, but their incompetence robs them of the metacognitive ability to realize it.” –  Dunning & Kruger


Why is it Important?

The Dunning-Kruger effect is highly evident in the workplace. When you see your coworker using Microsoft Word or Excel and becoming frustrated when they attempt to use more advanced functions to complete a task, you may notice that they resort to blaming the machine for “being glitchy”. In reality, it is more likely that your coworker is unable to complete the task because they don’t possess the knowledge to use more advanced functions and the true limitation is their own skill level.


Dunning-Kruger Effect Applied 

  1. Workplace evaluations The Dunning-Kruger effect can lead people to underperform because they don’t recognize what they could be doing better in their work, or more fundamentally, what good performance even looks like. If we were able to recognize our failings we would be more receptive to constructive criticism and set about fixing them. Self-evaluations programs in which employees are forced to confront their own skill deficiencies can encourage less-biased performance reviews. These programs address the problem created by the bias.
  2. Overconfidence between Men and Women – Dunning and Ehrlinger studied whether the Dunning-Kruger effect was different between men and women. To do so, they quizzed male and female college students on scientific reasoning. Before the quiz, the students rated their own scientific skills. The participants were told: “We wanted to see whether your general perception of Am I good in science? shapes your impression of something that should be separate: Did I get this question right?”  The study revealed that the women rated themselves more negatively than the men did on scientific ability. On a scale of 1 to 10, the women gave themes a score of 6.5 on average whereas the men gave themselves a score of 7.6. In terms of self-assessing how well the respondents thought they did the women thought they got 5.8 out of 10 questions right whereas men gave themselves a 7.1 These results are particularly telling because for the actual results their average was almost the same (woman scored 7.5 and men 7.9 on average).

TDL Insights 

Lateness, Defaulting on Commitments, and the Dunning-Kruger Effect 

Making plans is one way we attempt to optimize our productivity. However, we are often overly ambitious about what we can accomplish in a fixed amount of time. This phenomenon relates to both the planning fallacy and the Dunning-Kruger Effect. When we are bad at something, we believe we are better at it than we actually are and thus we assume we can complete a given task effectively and in a timely manner.


Further reading

Line, Jonathan. “Why You Might Not Be Sticking To Your Plans”. February 2017. The Decision Lab. https://thedecisionlab.com/might-not-sticking-plans/


Kruger, J., & Dunning, D. (1999). Unskilled and unaware of it: How difficulties in recognizing one’s own incompetence lead to inflated self-assessments. Journal of Personality and Social Psychology, 77(6), 1121-1134

Ehrlinger, Joyce, Kerri Johnson, Matthew Banner, David Dunning, and Justin Kruger. 2008. “Why the Unskilled Are Unaware: Further Explorations of (Absent) Self-Insight among the Incompetent.” Organizational Behavior and Human Decision Processes 105 (1): 98–121. https://doi.org/10.1016/j.obhdp.2007.05.002.