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.