Interesting, so the eye does that even when we are trying to look to one side? That's odd, since we don't perceive much during the head turn, itself. I need to go find some studies to read!I'm enjoying this discussion.
So..
The hand is quicker than the eye.
Action is quicker than reaction.
Ergo- If I punch first, you shouldn't be able to slip that punch. (if it's in your repertoire) but you will many times.
I know it's a straw man argument, but how else was I going to get to use the word ergo?
Actually - the eye runs slightly slower than the turn of the head. Less than ten milliseconds. Interestingly enough, when the head snaps either right or left, the eyes move slightly in the opposite direction in order to keep focus within the center of the field of vision.