Q: According to scientists, a Ouija board is not all trickery or illusory correlation. What's the real physiological effect to help explain its workings?

A: In case you've never used one, it allows players to ask questions of the spirit world and get answers from a planchette, or marker, that moves across a board marked with letters, numbers, and the words "yes," "no," "maybe" and "good-bye," say Stephen Macknik and Susana Martinez-Conde in "Sleights of Mind." It's believed that the players themselves unconsciously move the planchette via the "ideomotor effect," where voluntary muscles make tiny movements outside of conscious awareness that can cause the marker to drift toward one letter, then another, and so on. Though the movements are self-generated, the illusion of an outside force is compelling.

Now not to be killjoys, but "if you want to expose the illusion of the Ouija board, ask the players to put on blindfolds as they move the planchette. Their spelled out messages will be gibberish."

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