Theideomotor phenomenon is apsychological phenomenon wherein a subject makes motionsunconsciously. Also calledideomotor response (orideomotor reflex) and abbreviated toIMR, it is a concept inhypnosis and psychological research.^[2] It is derived from the terms "ideo" (idea, ormental representation) and "motor" (muscular action). The phrase is most commonly used in reference to the process whereby a thought or mental image brings about a seemingly "reflexive" or automaticmuscular reaction, often of minuscule degree, and potentially outside of theawareness of the subject. As in responses to pain, the body sometimes reacts reflexively with an ideomotor effect to ideas alone without the person consciously deciding to take action. The effects ofautomatic writing,dowsing,facilitated communication,^[3]applied kinesiology, andouija boards have been attributed to the phenomenon.^[4][5]

The associated term "ideo-dynamic response" (or "reflex") applies to a wider domain, and extends to the description of all bodily reactions (including ideo-motor and ideo-sensory responses) caused in a similar manner by certain ideas, e.g., the salivation often caused by imagining sucking a lemon, which is a secretory response. The notion of an ideo-dynamic response contributed toJames Braid's first neuropsychological explanation of the principle through whichsuggestion operated inhypnotism.

With the rise ofSpiritualism in 1840s,mediums devised and refined a variety of techniques for communicating, ostensibly, with the spirit world includingtable-turning andplanchette writing boards (the precursor to laterOuija boards). These phenomena and devices quickly became the subject of scientific investigation.^[6][7]

The termideomotor was first used byWilliam Benjamin Carpenter in 1852. In ascientific paper that specifically discussed the means through whichJames Braid's "hypnotism" produced its effects,^[8] Carpenter derived the wordideomotor from the componentsideo, meaning "idea" or "mental representation", andmotor, meaning "muscular action". In the paper, Carpenter explained his theory thatmuscular movement can be independent ofconscious desires or emotions;^[8] hence the alternative term "Carpenter effect".

Carpenter was a friend and collaborator of James Braid, the founder of modern hypnotism. Braid soon adopted Carpenter's ideo-motor terminology, to facilitate the transmission of his most fundamental views, based upon those of his teacher, the philosopherThomas Brown,^[9] that the efficacy of hypnotic suggestion was contingent upon the subject's concentration upon a single (thus, "dominant") idea.

In 1855, Braid explained his decision to abandon his earlier term "mono-ideo-motor", based on Carpenter's (1852) "ideo-motor principle", and adopt the more appropriate and more descriptive term "mono-ideo-dynamic".^[10] His decision was based upon suggestions made to Carpenter (in 1854) by their friend in common,Daniel Noble, that the activity that Carpenter was describing would be more accurately understood in its wider applications (viz., wider than pendulums and ouija boards) if it were to denominated the "ideo-dynamic principle":^[11]

In order that I may do full justice to two esteemed friends, I beg to state, in connection with this termmonoideo-dynamics, that, several years ago, Dr. W. B. Carpenter introduced the termideo-motor to characterise the reflex or automatic muscular motions which arise merely from ideas associated with motion existing in the mind, without any conscious effort of volition. In 1853, in referring to this term,Daniel Noble said, "Ideo-dynamic would probably constitute a phraseology more appropriate, as applicable to a wider range of phenomena." In this opinion I quite concurred, because I was well aware that an idea couldarrest as well asexcite motion automatically, not only in the muscles of voluntary motion, but also as regards the condition ofevery other function of the body. I have, therefore, adopted the termmonoideo-dynamics, as still more comprehensive and characteristic as regards the true mental relations which subsist during all dynamic changes which take place, in every other function of the body, as well as in the muscles of voluntary motion.^[12]

Scientific tests by the English scientistMichael Faraday, Manchester surgeonJames Braid,^[13] the French chemistMichel Eugène Chevreul, and the American psychologistsWilliam James andRay 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".^[14] They also show that suggestions that can guide behavior can be given by subtle clues (Hyman 1977).

Some operators claim to use ideomotor responses to communicate with a subject's "unconscious mind" using a system of physical signals (such as finger movements) for the unconscious mind to indicate "yes", "no", "I don't know", or "I'm not ready to know that consciously".^[15]

A simple experiment to demonstrate the ideomotor effect is to allow a hand-held pendulum to hover over a sheet of paper. The paper has words such as "yes", "no", and "maybe" printed on it. Small movements in the hand, in response to questions, can cause the pendulum to move towards the words on the paper. This technique has been used for experiments inextrasensory perception,lie detection, and ouija boards. This type of experiment was used byKreskin^[16] and has also been used by illusionists such asDerren Brown.^[17]

A 2019 study of automatic pendulum movements using a motion capture system showed that pendulum effect is produced when the fingers holding the pendulum generate an oscillating frequency close to the resonant frequency of the pendulum. At an appropriate frequency, very small driving movements of the arm are sufficient to produce relatively large pendulum motion.^[18]

It is strongly associated with the practice ofanalytical hypnotherapy based on "uncovering techniques" such asWatkins' "affect bridge",^[19] whereby a subject's "yes", "no", "I don't know", or "I don't want to answer" responses to an operator's questions are indicated by physical movements rather than verbal signals; and are producedper medium of a pre-determined (between operator and subject) and pre-calibrated set of responses.^[20]

• Media related toIdeomotor phenomenon at Wikimedia Commons

• Human physiology
• Hypnosis
• Phenomena
• Parapsychology

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