Your describing what i did at school for an hour a day for 7 years. I was never sure whether i was inducing a state where it was possible for distortions to happen, or if my imagination was going wild.
My practice was i would close my eyes for the prayers and when i reopened them i was miles away. Almost as if my response to being force to chruch was to create alternate imaginary belief system.
Im not sure if it helps in what your trying to achieve but basically optic illusions really help me with working out whether it is a true hallucination (whoa im seeing a dragon in broad daylight) or if its the conclusion of seeing shadows.