Why we're all overconfident

Here's a phenomenon we've all noticed: a friend insists they're right about something, refuses to waver in spite of doubters, and then consults Wikipedia, only to realize that they're dead wrong.
We might laugh, but it happens all the time. Think about those poor people on Jay Leno or Jimmy Kimmel who get cornered on a topic and say things that are decidedly untrue.

There's actual science behind that phenomenon, argues Cornell professor David Dunning. He's recreated similar experiments in the lab, asking subjects about fictions political figures, for example, or nonexistent cities — and gets much the same results as the late night hosts do.
"What we find is that people are quite ready to start talking about things they can't possibly know anything about because we made that thing up in our office just the week before," he explains.
The rationale for the behavior may be pretty sound, when you consider basic human behavior and communication.
"Whenever we're talking to other people, we j