Over at Neatorama, they've posted this great little diagram of the various ways you can trick your mind into doing weird things:
Click the image for a closer look.
The most interesting of these techniques is the one in the upper left corner. It's called the Ganzfeld Procedure, a method for tricking the mind into seeing images through sensory deprivation. Wikipedia has this to say about it:
A ganzfeld experiment (from the German for “entire field”) is a technique used in the field of parapsychology to test individuals for extra-sensory perception (ESP). It uses homogeneous and unpatterned sensory stimulation to produce an effect similar to sensory deprivation. The deprivation of patterned sensory input is said to be conducive to inwardly-generated impressions. The technique was devised by Wolfgang Metzger in the 1930s as part of his investigation into the gestalt theory.
Parapsychologists such as Dean Radin and Daryl J. Bem say that ganzfeld experiments have yielded results that deviate from randomness to a significant degree, and that these results present some of the strongest quantifiable evidence for telepathy to date. Critics such as Susan Blackmore and Ray Hyman say that the results are inconclusive, and call for further study before such results can be scientifically accepted.
Pretty awesome if you ask me. I'm going to try it out tonight, I'll post the results tomorrow...