I was confused by the answers too, but from the experiments I have done as posted before, I think the eye position means the pupil, it’s position will change if you move your pupil to see different directions. Jenny said that this kind of change might due to fluctuations, but when I move pupil to look at the screen from left to right, the ‘X’ coordinate increases, so the change is following the coordinates system.
Can you help me with this? Thanks a lot.