[lordnacho]

I don't buy that at all.

Think about the potential hidden states (already knows the answer vs blank) vs the evidence you could get from the person answering right or wrong. What should your prior be? Surely that there's a very large chance this person is not a genius. Now how much is that going to move, given that by far most people are not geniuses?

To put it another way, what would you do to impress someone following your reasoning? I would pretend like I didn't know it, and then act out the miraculous direct line to the answer.

As for looking at how people behave in front of a hard problem, what on earth do you know about that? Do you have evidence connecting people's behaviour to subsequent on-the-job performance, both for people you hired and those you didn't?