How Do You Know Where You're Looking?

In the lab, we have a couple of eye trackers that allow us to figure out where you're looking. And then we also work on where your attention goes even when your eyes are static. We can actually read the electrodes on the back of your head and tell whether you're paying more attention on the left right. So for some of the geeker syche level experiments, would really want to dig under the hood and find out what's going on, we've used that technique. But i think for most practical purposes, the eye tracker gets that done.