The Dunning-Kruger Effect

Watching the women’s Arial finals the other night gave me a tremendous sense of respect for their ability (Great job Laura Peel!!). However, waking up to the news of Norway’s curling team and their pants got me thinking that surely curling is something I could do. I mean I have played bowls before, surely, I would be average at curling. I think it’s safe to say that I would be well below average at curling and nowhere near Olympic level but why would I initially think I could do it?

The Dunning-Kruger effect occurs when individuals with low skill levels overestimate their abilities, conversely, individuals with high skill levels underestimate their abilities. This was shown in a study by Kruger & Dunning (1999) where undergraduate students of introductory courses in psychology were self-assessed on the domains of intellectual skills, grammar and sense of humour. Following the self-assessments, the students then estimated where they ranked on the results within the class. Results found that competent students underestimated their class ranks, while incompetent students with test scores that placed them in the 12th percentile estimated they ranked in the 62nd percentile.

Kruger & Dunning (1999) reasoned that the illusory superiority that occurs in the low skilled individuals is due to a metacognitive inability to recognise their own ineptitude. As stated by Dunning (2005), “If you’re incompetent, you can’t know your incompetent. The skills you need to produce the right answer are exactly the skills you need to recognise what a right answer is”.

Metacognition is something that I will be talking about more in-depth as the year goes on as it is central to many areas of our life. Metacognition (meta meaning ‘beyond’ & cognition meaning ‘thinking & awareness’) is the process of thinking about thinking. Metacognition is our ability to self-analyse and reflect on our thoughts, motivations and behavioural processes. In it’s absence we are left with little self-reflection or self-awareness, making objective evaluations about our competence or incompetence extremely difficult.  

In a study by Simons (2013), competitive bridge players predicted their results for bridge sessions before playing and received feedback about their actual performance following each session. Despite knowing their own relative skill and showing unbiased memory for their performance, they made overconfident predictions consistent with a Dunning–Kruger effect. This bias persisted even though players received accurate feedback about their predictions after each session. The finding of a Dunning–Kruger effect despite knowledge of relative ability suggests that differential self-knowledge is not a necessary precondition for the Dunning–Kruger effect. At least in some cases, the effect might reflect a different form of irrational optimism.

As for highly skilled individuals, Kruger & Dunning (1999) reasoned that due to their higher skill levels, tasks were completed with a higher level of ease. Due to this higher level of ease, assumptions were made that the task is easier than it is and therefore more people would be competent in completing it. I often find this prominent when talking to someone about their job, they talk very quickly about complicated processes that I have very little understanding of with the assumption that everybody would surely understand such processes.   

The Dunning-Kruger effect has been noticed for centuries and is reflected in one of my favourite quotes by Albert Einstein, “As our circle of knowledge expands, so does the circumference of darkness surrounding it”. Over confidence and irrational optimism can be the result of not growing our circle of knowledge and therefore having little ability for introspection and self-evaluation. This can lead us to not only make unhealthy decisions but to continue to make unhealthy decisions


Dunning, D. (2005). Self-insight: Roadblocks and Detours on the Path to Knowing Thyself. New York: Psychology Press. pp. 14–15

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. Retrieved from

Simons, D. J. (2013). Unskilled and optimistic: Overconfident predictions despite calibrated knowledge of relative skill. Psychonomic Bulletin & Review, 20(3), 601-7. Retrieved from