Human beings, as it turns out, have too much faith in themselves. The detection of falsehood is scarcely the only domain where they overestimate their abilities. Similarly, most people think they are likely to live longer than the mean. In a classic 1977 paper in the Journal of Experimental Psychology, Baruch Fischhoff, Paul Slovic, and Sarah Lichtenstein reported that people often pronounce themselves absolutely certain of beliefs that are untrue. Subjects would declare themselves 100 percent sure that, say, the potato originated in Ireland, when it actually came from Peru.
Overconfidence is nearly universal.
Not according to a widely publicized paper in last December's issue of the Journal of Personality and Social Psychology. Those who scored in the twelfth percentile in the logic test, for example, imagined that their skill in logic was at the sixty-eighth percentile. Now, if you are among the competent, you might derive some consolation from this research, since it implies that you are unlikely to be grossly overconfident. And there is more to worry about. Overconfidence also tends to rise with the complexity of the problem.