I've noticed that when you're going about your day to day life you can pull your attention or concentration so you visualise things in your head or actually out in the world.
I've found that when trying to ap as well my eyes roll back, sometimes or feel like my attention is sunk in my head, but I can also focus on the eyelids and seeing ahea into the blackness - the problem being they start to open.

The part where you watch behind your eyelids, is that the kind of thing you want to have when trying to ap, or do you want your eyes more back in your head, so to speak?