What's the secret to a Ouija board? Up until World War I, the device was treated like a harmless parlor game, but people began debating the board's paranormal properties after American Spiritualists touted it as a divining tool. All occultism aside, we still argued about whether the board's "messages" were manipulated consciously or subconsciously.
To settle the argument, Sunker Abaji Bisey, an Indian scientist, invented a "spirit typewriter," or a ouija board that used blank typewriter keys instead of letters. In a patent from 1922, Bisey wrote that he developed the device as a means to receive so-called spiritual transmissions without human interference. Each key was attached to a letter or number hidden under the circular tray. While using the ouija board, the operator would spin the device several times before allowing "the spirits" to type on the blank keys using the handheld triangle. That ensured that the operator could not in any way see the letters the Ouija board was supposedly selecting. At the end of the session, you could pull out the ribbon to see if there were a message on it. The spirit typewriter seems to have vanished--we're not sure if it ever succeeded in debunking the powerful Ouija board.
(Scientists now see the Ouija board, which is used in most corners of the world, as an example of the ideomotor effect in action: an unconscious physical movement. Basically, we're doing it without knowing we're doing it. Except when people know they're doing it. Which they sometimes do.)
Read the full story in "Is the Ouija-Board Controlled Subconsciously?"