Maybe we could address cheating in online chess by showing various images throughout a game.
The intuition here is that these images will have some impact on your thinking patterns.
So the idea is to see whether you are reacting as a typical human being would when viewing these images while playing chess.
For example, some images may have a negative effect in tactical positions.
One can have players play a against a computer every once in a while without telling them to see if they are cheating.