Ideomotor effect
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The ideomotor effect involves small bodily movements that occur involuntarily and subconsciously, rather than by deliberate decision. Some psychologists describe it as a form of dissociation, since the brain sends signals to the muscles directly, bypassing human consciousness. The term was coined by psychologist/physiologist William B. Carpenter in 1852.
The biological explanation for the existence of the ideomotor effect is that it involves the same involuntary and unconscious movements that make up our non-verbal communication. This includes facial expressions and (small) changes in posture. Though non-verbal communication plays a lesser role among humans than among animals, because humans have speech (verbal communication), it is still important. Some estimate that more than 80% of communication in humans is non-verbal. Many courses in professional communication train people to be more aware of non-verbal communication.
When magnified in certain circumstances this unexpected behaviour can have the appearance of being a supernatural occurrence. Skeptics have proposed the ideomotor effect as an explanation for phenomena observed in Ouija board séances, automatic writing, dowsing, and the use of a pendulum.
Probably the first major scientist to become concerned about the mischief being created by ideomotor action, although he did not know the concept by this name, was the French chemist Michel Eugène Chevreul. Chevreul became interested in the experiments of some of his fellow chemists around the beginning of the nineteenth century. These colleagues were using what was known as "the exploring pendulum" to analyze chemical compounds.
The first recorded use of the exploring pendulum occurred around 371 C.E. A priest would bow over a plate, the edge of which was marked with the letters of the alphabet. This "diviner" or "oracle" would hold a ring, suspended from a thin thread, over the center of the plate. A question would be put to the priest. The movements of the ring would then be observed. When the ring was set in motion, it would swing toward one of the letters. This letter would be recorded; then the same process would be used to select another letter. This would continue until one or more words, which answered the question, would be generated. In this, we see the origins of the modern Ouija board, used to this day by occultists for divination purposes.
(The following two paragraphs were taken surreptitiously from Ray Hyman's article, "The Mischief Making of the Ideomotor Effect" in Science Meets Alternative Medicine pg. 101. They need to be researched and re-written.)
In 1808, a Professor Gerboin of Strasbourg wrote an entire book on use of the pendulum for chemical analysis. As a budding scientist, Chevreul was intrigued, but he remained skeptical. He was surprised, however, to find that the pendulum worked as advertised when he tried it over a dish of mercury. He carried out more tests, however. To see if a physical force was responsible for the movement of the pendulum, he placed a glass plate between the iron ring and the mercury. To his surprise, the oscillations diminished and then stopped. When he removed the glass plate, the pendulum movements resumed. He next suspected that the pendulum moved because it was difficult to hold his arm steady. When he rested his arm on a support, the movements diminished but did not stop altogether.
Finally, Chevreul did what none of his predecessors had thought of doing. He conducted the equivalent of what we would call a double-blind trial. He blindfolded himself and then he had an assistant interpose or remove the glass plate between the pendulum and the mercury without his knowledge. Under these conditions, nothing happened. Chevreul concluded, "So long as I believed the movement possible, it took place; but after discovering the cause I could not reproduce it." His experiments with the pendulum show how easy it is "to mistake illusions for realities, whenever we are confronted by phenomena in which the human sense-organs are involved under conditions imperfectly analyzed." Chevreul used this principle of expectant attention to account for the phenomena of dowsing, movements of the exploring pendulum, and the then current fad among spiritualists, table-turning.
External links
- The Skeptics' Dictionary: Ideomotor Effect (http://www.skepdic.com/ideomotor.html)
- Quackwatch: How People Are Fooled by Ideomotor Action (http://www.quackwatch.org/01QuackeryRelatedTopics/ideomotor.html)