Via In Socrates’ Wake, I find this psychological gem:
[C]ognitive science offers some fairly sobering observations about our ability to judge ourselves and others…
[T]wo Cornell psychologists began with the following assumptions.
1. Incompetent individuals tend to overestimate their own level of skill.
2. Incompetent individuals fail to recognize genuine skill in others.
3. Incompetent individuals fail to recognize the extremity of their inadequacy.
To put their theories to the test, the psychologists asked a group of Cornell undergraduates to undergo a series of self-assessments, including tests of logical reasoning taken from a Law School Admissions Test preparation guide. Prior to being shown their test scores, the subjects were asked to estimate how they thought they would fare in comparison with the others taking the tests.
On average, participants placed themselves in the 66th percentile, revealing that most of us tend to overestimate our skills somewhat. But those in the bottom 25 percent consistently overestimated their ability to the greatest extent. For example, in the logical reasoning section, individuals that scored in the 12th percentile believed that their general reasoning abilities fell at the 68th percentile, and that their overall scores would be in the 62nd percentile. The authors point out that the problem was not primarily underestimating how others had done; those in the bottom quartile overestimated the number of their correct answers by nearly 50 percent. Similarly, after seeing the answers of the best performers — those in the top quartile — those in the bottom quartile continued to believe that they had performed well.