Well I got both those questions right by following the heuristic that the most obvious answer off the top of my head would not be the answer. To my mind on any

Well I got both those questions right by following the heuristic that the most obvious answer off the top of my head would not be the answer. To my mind on any test that was supposed to be hard the appearance of any obvious an answer triggers me to check for the proverbial trick question. On the other hand, most brain puzzler type questions that get discussed on HN (for example interview questions at Google) I find to be damn hard. I can't imagine that "smart" people would do worse than "stupid" people on truly hard problems. I guess that is the area of bias being pointed to in the OP.