There is a term, something like "double think" or "second guess", I believe, but I am pretty sure it's not either of those. It refers to the act of getting into an opponent's head and imagining what they're thinking, then opting for the obvious choice that's so simple, they'll never think you'd try it.
That made no sense.
Classic example: the purloined letter. Since the obvious places are the first places someone would look for something, they're also, by proxy, the LAST places the searcher would think that the hider would hide something. So the hider, knowing this, elects to hide the object in plain sight.
Another, perhaps simpler one, from my own story: two people are on the run. They hide out in a particular house for a period of time, are discovered, and escape. They move around to a few different places, each time just a few steps ahead of their pursuers. After a while they consider returning to the first house, because it's such an obvious hiding place, nobody would think to look there.
Am I on something? Or is there a term, somewhere, that refers to this line of thinking specifically?