Why ‘We Are All Confident Idiots’ – The Dunning-Kruger Effect

‘ignorance more frequently begets confidence than does knowledge’ – Darwin

Dunce's Cap.Why is it that a little bit of knowledge appears to super-inflate peoples estimation of their abilities? Whereas a significant amount of knowledge in a field makes one painfully aware of their own limitations. Take for example a novice car driver, or pilot. Once most individuals get over the initial fear and trepidation of driving or flying, they are at a significantly higher risk of accident, and also over-estimate their own competence at the task. 1 However, those experienced drivers and pilots conversely underestimate their competence at the task. Now this phenomenon has been observed regularly throughout history, as noted by Darwin, Bertrand Russell and many others. But it was with David Dunning and Justin Kruger’s 1999 JPS article that it was formally described — and subsequently entitled the Dunning-Kruger Effect. 2

So what is the Dunning-Kruger effect? Well it is the tendency of those with little to no knowledge of a specific domain tending to inflate their self-assessments of their mastery of that domain. Simply put, people who know a little of a field think they know much more than they actually do. In fact in the study the participants test scores placed them lowly on the 12th percentile, but on average their self-assessment was around the 62nd percentile. That is a rather significant over-estimation of capability in an area. Conversely those who performed well in the text under-estimated their self-assessment. As Albert Einstein sagely observed: ‘The more I learn, the more I realize how much I don’t know’ and the inverse is true for novices.

dkgraphFrom this it is relatively easy to see the application to academic fields. Students and novices in a field will have a tendency to over-estimate their knowledge in a domain, while those who are SMEs underestimate in their presentations. This is highly common in complex fields where people may be able to absorb a small amount at the lay level, and then extrapolate their knowledge out to the entire domain. Notably without accounting for the pitfalls, caveats and speed bumps along the way that the experienced person will be only too aware of. But this is also likely exacerbated in areas where people are engaging in inter-disciplinary work. Being an SME in one domain does not instantly sideline the Dunning-Kruger effect from any other domain you may engage in.

Is this just self-aggrandisement or malicious hubris? Well, not quite, as Dunning observes this isn’t a conscious problem, it is a metacognitive issue. The Dunning-Kruger effect works at a level that is prior to any confirmation bias from cognitive dissonance or similar. As Dunning writes the effect ‘is “pre” cognitive dissonance. It’s not that people are denying their incompetence, they literally cannot see it in the first place, and so there’s nothing to deny or experience dissonance over’ 3 In fact logically one cannot see the effect of the bias, as to have the self-insight to recognise the ineptitude you need the expertise that you lack in that field.

So how to combat it? Well as a metacognitive bias it is hard to combat simply by knowledge of the bias itself. Of course knowing about it may make you question your self-assessments. But it wont help you catch the thinking in the act, as you can’t see the over-estimation errors anyway. Rather you need do avoid making the error in the first place, and the way that Dunning suggests you do that is via learning. Competence and learning in the fields that you are engaged in is the way to stave off this bias. However, he also observes that you can mitigate against the effect in the early stages of learning through finding those who provide you with useful assessments and getting them to act as a sounding board or cabinet. 4 I would add one more aspect to mitigating the Dunning-Kruger effect: humility. A lot of the effect is about making out that you know something when you don’t. Here humility can help by recognising that you don’t know everything in a domain, and having the ability to outwardly acknowledge this. Of course this can be hard for SMEs as they are expected to know everything in that domain. Nevertheless, those three aspects: learning, sounding-boards and humility; will help with mitigating against the bias.

By way of conclusion David Dunning has a fascinating article from late last year in the Pacific Standard available here: We Are All Confident Idiots (http://www.psmag.com/health-and-behavior/confident-idiots-92793) an interesting Reddit AMA here: http://www.reddit.com/r/science/comments/2m6d68 and the original paper is available here: http://psych.colorado.edu/~vanboven/teaching/p7536_heurbias/p7536_readings/kruger_dunning.pdf

Tell me how you mitigate against this effect in the comments. But let me leave you with this wonderful piece of self-recognition from Dunning & Kruger’s original journal paper:

Although we feel we have done a competent job in making a strong case for this analysis, studying it empirically, and drawing out relevant implications, our thesis leaves us with one haunting worry that we cannot vanquish. That worry is that this article may contain faulty logic, methodological errors, or poor communication. Let us assure our readers that to the extent this article is imperfect, it is not a sin we have committed knowingly. 5


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  1. Pavel, Samuel, Michael Robertson, and Bryan Harrison. “The Dunning-Kruger Effect and SIUC University’s Aviation Students.” Journal of Aviation Technology and Engineering 2, no. 1 (2012). http://docs.lib.purdue.edu/jate/vol2/iss1/6.
  2. Kruger, Justin, and David Dunning. “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, no. 6 (1999): 1121–34.
  3. David Dunning AMA: http://www.reddit.com/r/science/comments/2m6d68
  4. http://www.reddit.com/r/science/comments/2m6d68/science_ama_seriesim_david_dunning_a_social/cm1jnlc
  5. Justin Kruger and David Dunning, “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, no. 6 (1999): 1121–34.
  • Gillian Porter

    I think this graph works with what you’re saying…