The GM's point of view
Interesting topic.
Many GM's often when they look at the board aren't really looking at the board. They're doing their calculation in their head. So they sometimes look to the side, or close their eyes, even get up and walk around. More so in the longer time games than short blitz though.
Karpov is interesting in that in his games I noticed he often does a quick scan of the whole board. I'm guessing to take inventory so that he doesn't forget about that B on a1 or something. Maybe a habit he picked up very early and become procedure?
Do you know of anybody who has done that to the players of a chess game?