Are dumb people too dumb to know that they're dumb? Apparently so, according to research. From Life's Little Mysteries:
With more than a decade's worth of research, David Dunning, a psychologist at Cornell University, has demonstrated that humans find it "intrinsically difficult to get a sense of what we don't know." Whether an individual lacks competence in logical reasoning, emotional intelligence, humor or even chess abilities, the person still tends to rate his or her skills in that area as being above average.
Dunning and his colleague, Justin Kruger, formerly of Cornell and now at New York University, "have done a number of studies where we will give people a test of some area of knowledge like logical reasoning, knowledge about STDs and how to avoid them, emotional intelligence, etcetera. Then we determine their scores, and basically just ask them how well they think they've done," Dunning said. "We ask, 'what percentile will your performance fall in?'"
The results are uniform across all the knowledge domains: People who actually did well on the test tend to feel more confident about their performance than people who didn't do well, but only slightly. Almost everyone thinks they did better than average. "For people at the bottom who are really doing badly — those in the bottom 10th or 15th percentile — they think their work falls in the 60th or 55th percentile, so, above average," Dunning told Life's Little Mysteries. The same pattern emerges in tests of people's ability to rate the funniness of jokes, the correctness of grammar, or even their own performance in a game of chess. "People at the bottom still think they're outperforming other people."