For decades people have claimed that spirits control Ouija boards.
However, scientists now claim the "mysterious" movement on a Ouija board is caused by the "ideomotor effect," when muscles can move without a person being aware.
According to BBC.com, the people make the board movements unconsciously, but claim it's a spirit or some other supernatural being.
Ouija boards were invented in the 1890s as a parlor game, but were also used by people trying to contact the dead during the First World War. The board game also become popular because of scary movies such as "The Exorcist."
Scientists explain the Ouija board effect by hanging a ring from a foot-long piece of string held by a human. Even if the person's arm is held still, the ring will still sway because the string helps to exaggerate tiny movements of the person holding the string.
Apparently, the same principle applies to Ouija boards and so-called "dowsing rods" that are supposed to detect everything from water to gold under the ground.
Psychologist Daniel Wegner, who died last month, theorized that the mental processes that control movement are not connected to different mental processes that decide what caused the movement.