The ideomotor effect has to do with the influence that suggestion has on involuntary or subconscious actions. In motor behavior, there are two parts to the brain activity. The first is the activity that results in the motor activity; the second is the registration of that activity in the conscious mind. The ideomotor effect happens when the second part, the conscious registration, is circumvented.
The effect was first observed by William B. Carpenter in 1852, in his investigation of dowsing. He proposed the ideomotor effect as a third class of unconscious behavior, along with excitomotor (such as breathing and swallowing) and sensorimotor (reflex actions).
The ideomotor effect has been well documented; however, it still remains an effect that is largely unknown to most people, including scientists.
A classic example of the ideomotor effect in action dates back to the use of a held pendulum as far back as 371 CE. An operator would hold the pendulum and attribute certain meanings depending on which direction the pendulum would swing. Priests used this technique to channel divine messages. Alchemists used it to determine the composition of an object. The results were very convincing, until double-blind trials failed to yield the same results.
The ideomotor effect is sometimes known as the Clever Hans effect. It is named after a horse, Clever Hans, who was said to be able to understand and solve basic arithmetic problems and give the answer by tapping its hoof. It was later found out that the horse had no mathematical abilities, but was simply picking up visual cues from its owner when to start and stop tapping.
Many phenomena have been attributed to the ideomotor effect, including:
- Ouija boards
- Automatic writing
- Facilitated communication
- The movement of the table and other objects in seances
- An apparent "life energy," or chi, in Chinese medicine
- Action- the actual motion of the pendulum or other object, which is the result of minor unconscious motor activity, usually greatly amplified
- Projection - the responsibility for the action is connected to something other than the operator
- Attribution - because of the projection, the action is attributed to some new science, undiscovered phenomenon, or paranormal activity
- Delusion - the operator is considered to be someone with an exceptional ability
- Self-confirmation - once the ideomotor effect begins to take place, psychological reinforcement can amplify the effect and prevent falsification in the mind of the operator