The ouija, also known as a spirit board or talking board, is a flat board marked with the letters of the alphabet, the numbers 0–9, the words "yes", "no", "hello", and "goodbye", along with various symbols and graphics. It uses a planchette as a movable indicator to indicate the spirit's message by spelling it out on the board during a séance. Participants place their fingers on the planchette, and it is moved about the board to spell out words. "Ouija" has become a trademark that is often used generically to refer to any talking board. Following its commercial introduction by businessman Elijah Bond on July 1, 1890, the Ouija board was regarded as a harmless parlor game unrelated to the occult until American Spiritualist Pearl Curran popularized its use as a divining tool during World War I. Paranormal and supernatural beliefs associated with Ouija have been harshly criticized by the scientific community, since they are characterized as pseudoscience. The action of the board can be parsimoniously explained by unconscious movements of those controlling the pointer, a psychophysiological phenomenon known as the ideomotor effect.