On sketches that illustrate eye focus, it is shown that humans, when looking straight ahead, focus their vision at a point between their eyes. I came to the conclusion that it is not true, and we focus similarly to the picture on the right.
I have a small experimental proof for it. Look in the mirror. What point are you looking at most of the time? For me, it is the right eye. It is the ‘main’ eye. If you are looking at your eye too, try switching focus to a different eye and keep it there for some time. It might feel weird, and I think that’s because you are switching your main eye. If you got acquainted with that feeling, try looking around with a switched main eye. It certainly feels as if you are focusing similarly to the right picture.