To be blunt, it’s possible to be so dumb that you’re unaware of your own idiocy (look to the left, look to the right … you get the point; that is, unless you’re dumb). Put another way, many dumb people think they’re smart. This, of course, is dumb.
How dumb are they? (Insert punch line here.)
In the classic study of overconfident idiots, Justin Kruger and David Dunning of Cornell University found that subjects scoring in the lowest quartile on tests of humor, grammar, and logic were also the most faulty in their self-assessments, predicting they would score in the 62nd percentile, when in fact they scored in the 12th.
Photocopy. Cut. And post this near your office watercooler.
The Lemon-Juice Thief
In their article in the Journal of Personality and Social Psychology, Dunning and Kruger offer the following case to illustrate overconfidence due to idiocy:
In 1995, a man named McArthur Wheeler was arrested for robbing two banks. The police had no trouble tracking him down: During the robberies he’d made no visible attempt at disguise and so had been captured clearly by the banks’ security cameras. When the cops showed him the damning surveillance footage, Wheeler protested, “But I wore the juice!” Apparently, he believed that rubbing his face with lemon juice would render it invisible to video cameras.