Ideomotor effect

The ideomotor effect is a psychological phenomenon wherein a subject makes motions unconsciously (i.e., without conscious awareness). As in reflexive responses to pain, the body sometimes reacts reflexively to ideas alone without the person consciously deciding to take action. For instance, tears are produced by the body unconsciously in reaction to the emotion of sadness, usually without any intervention of conscious will.

Stage hypnotists exploit the ideomotor effect for entertainment value, convincing volunteers to perform some action without consciously deciding to do so. The volunteers usually have no memory of their performance, much like sleepwalkers who are unaware that they are acting on stimulus existing almost entirely in their own minds. More subtle unconscious physical reactions are often used by magicians and illusionists to perform "mind-reading" tricks.

Automatic writing, dowsing, facilitated communication, and Ouija boards have also been attributed to the effect of this phenomena. Mystics have often attributed this motion to paranormal or supernatural force. Many subjects are unconvinced that their actions are originating solely from within themselves.

The term was first used in a paper discussing the means through which the Ouija board produced its results, by William Benjamin Carpenter in 1852. In the paper, Carpenter explained his theory that muscular movement can be independent of conscious desires or emotions.

Scientific tests by the English scientist Michael Faraday, the French chemist Michel Chevreul, and the American psychologists William James and Ray Hyman have demonstrated that many phenomena attributed to spiritual or paranormal forces, or to mysterious "energies," are actually due to ideomotor action. Furthermore, these tests demonstrate that "honest, intelligent people can unconsciously engage in muscular activity that is consistent with their expectations" (Hyman 1999). They also show that suggestions that can guide behavior can be given by subtle clues (Hyman 1977).

Some alternative medicine practitioners claim they can use the ideomotor effect to communicate with a patient's unconsciousness using a system of physical signals (such as finger movements) for the unconscious mind to indicate "yes", "no" or "I'm not ready to know that consciously". Scientific studies have not been conducted to support this method.