clipped from en.wikipedia.org

The Dunning-Kruger effect is the phenomenon wherein people who have little knowledge think that they know more than others who have much more knowledge.

Kruger and Dunning noted a number of previous studies which tend to suggest that in skills as diverse as reading comprehension, operating a motor vehicle, and playing chess or tennis, "ignorance more frequently begets confidence than does knowledge" (as Charles Darwin put it). They hypothesized that with a typical skill which humans may possess in greater or lesser degree,

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.
4. If they can be trained to substantially improve their own skill level, these individuals can recognize and acknowledge their own previous lack of skill.