by Steven D. Johnson
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The Dunning-Kruger Effect
Last month's rant about the unhandyman that butchered dozens of projects in the house I am
remodeling provoked some interesting responses from readers. Bruce, from Medway, MA suggested that
I may have encountered the Dunning-Kruger effect, which was first identified in 1999, and which
suggests that those who are unskilled often make poor decisions, but that their own incompetence
denies them the ability to appreciate their mistakes, giving them the illusion of superiority and
the feeling that they are "above average." Conversely, the Dunning-Kruger Effect postulates that
those who are highly skilled often underrate their own abilities.
Justin Kruger and David Dunning, at the time working at Cornell University, made clear that the
effect is not limited to the unskilled. Sometimes the skilled suffer from the same effect, which
they identified as a "paradoxical defect in the perception of skills," in oneself and in others.
They cited a 1994 study of college professors wherein 94% rated their own performance as above
average when judged against their peers. As my statistics professor friend insists, it is quite
impossible for 94% of any group to be above average for that same group.
As for the folks with high-level skills, it appears that some erroneously (and most probably
subconsciously) assume everyone else has those same skills, thus they underrate their own on a
relative basis. If you find that cutting dovetails is easy, something in your brain may say "This
must be easy for everyone," thus you may underrate your own capabilities on a comparative basis.
In a later paper, Kruger and Dunning suggest that the root cause of the effect is that poor
performers do not learn from feedback suggesting a need to improve.
It is interesting to note that there was some additional work done that may indicate that this is
an American phenomenon. The effect is muted in Europeans and with East Asians, it appears that the
opposite of the Dunning-Kruger Effect is true. East Asian people tend to underestimate their
abilities, with an aim toward improving the self and getting along with others.
This is all quite interesting, but my friend (thankfully, I am quite confident, one of the 6% of
college professors that has his feet firmly planted in the world of reality), suggested that
external influences would have an impact on the Dunning-Kruger Effect. For example, my unhandyman
may well have been receiving positive feedback from friends, family, and neighbors. Certainly it
would be plausible that a beloved spouse who tells you how handy, creative, and resourceful you are
could lead you to believe that your skills are, indeed, above average. That positive reinforcement
might lead you to undertake more and more projects.
That input sounds logical, but highly skilled people often also receive positive feedback, and
often the feedback is from others, outside the individual's circle of family and friends. This
feedback might carry even more weight, yet many high-performers still consider themselves less
It is a mystery to me, but one worth exploring further. An instructor once told me that the more
I learned, the more I would realize that I did not know. It may be that simple. In their first
paper, Dunning and Kruger quoted Bertrand Russell: "One of the painful things about our time is that
those who feel certainty are stupid, and those with any imagination and understanding are filled
with doubt and indecision."
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