In short, what their finding is, is that people who are really stupid don't even know how stupid they are because they are too stupid to understand how stupid they are, and conversely, people who are really intelligent underestimate how really intelligent they are, which is why they don't understand how other people aren't as smart as they are.
Examples of this can be seen any time you think of some gozzlehead picking up what he (and it's ALWAYS a 'he') thought was a dud firecracker, only to have it go off in his hand, or the guy who gets a severe injury at work from fooling around with the paper cutter and then, returning after a period of recuperating, demonstrates for his boss just what had gone wrong 5 weeks ago on his first morning back, resulting in another trip to the hand clinic.
(Then there was the guy who got injured by fooling around with the paper cutter when the paper cutter's husband showed up.)
|Cletus from The Simpsons. He was once beaten in tic-tac-toe by a chicken.|
You can see a video of John Cleese explaining all this.
I heard a wise man opine that there are four kinds of people: Those who know, and know they know; those two know, but don't know they know; those who don't know, and know they don't know; and those who don't know, and don't know they don't know.
That last group is supposed to be the worst to be around. I don't know.