Just watched a show on LSD and towards the end they had a study of three groups. One group of mentally ill people, one group of people on LSD and one group of perfectly normal people.
They showed them the picture of a hollow map from both the convex view and the concave view. None of the normal people could ever see the difference. But those on LSD AND mentally ill COULD see the difference.
They explained it something like....with certain areas of the brain shut down, there's more power to other parts of the brain which are able to process things much faster and more comprehensively. The test subjects invariably said that time seemed to slow down OR think they seemed to go much faster.