The Ideomotor Effect: Why a Pendulum Moves

What the ideomotor effect is

The ideomotor effect is the body's habit of turning a thought into a small movement without your deciding to move or noticing that you did. Simply picturing a direction, or expecting an outcome, is enough for the muscles in your fingers, wrist and arm to make tiny adjustments that way.

Most of the time those adjustments go unseen. A pendulum is different: a weight hanging from a chain magnifies every tremor of the hand, so movements too small to feel become an obvious swing, back and forth, side to side, or around in a circle.

The important word is "without": without conscious intent, without felt effort, and without any dishonesty. People watching a pendulum move usually feel, quite sincerely, that they aren't moving it. In one sense they're right. Their will isn't moving it; their expectation is.

Chevreul and the ring over mercury

The French chemist Michel-Eugène Chevreul was among the first to test the pendulum carefully. In an open letter to the physicist André-Marie Ampère, published in 1833 in the Revue des Deux Mondes, he described experiments he had run back in 1812 with an iron ring hanging from a thread.

Held over mercury, an anvil or a living animal, the ring swung; when he slid a glass plate underneath, it stopped. It looked like a force coming from the material. But when he rested his arm on a wooden support, the swing weakened, and when he was blindfolded it nearly vanished. He held the pendulum over the mercury for about a quarter of an hour and it never started again.

His conclusion: an involuntary muscle movement he couldn't perceive set the pendulum going, and watching the swing made it grow. Two decades later he expanded the subject into an 1854 book, De la baguette divinatoire, du pendule dit explorateur et des tables tournantes, on the divining rod, the so-called exploring pendulum and turning tables.

Carpenter and the word "ideomotor"

The English physiologist William Benjamin Carpenter coined the term "ideo-motor" in 1852, in a lecture published by the Royal Institution of Great Britain under the title On the influence of suggestion in modifying and directing muscular movement, independently of volition.

Carpenter was writing at the height of mesmerism and the new craze for hypnotism, and he wanted a physiological account of effects that many people credited to magnetic fluids or spirits. His idea was simple and powerful: a thought that fills your attention can produce movement on its own, much as a reflex answers a stimulus.

In that paper and in later writing, the same explanation was applied to the divining rod, the pendulum and, soon after, the tables that tipped and turned at séances. Decades later William James took up ideomotor action in The Principles of Psychology (1890), and the idea has been part of basic psychology ever since.

Faraday and table-turning

In 1853 table-turning was sweeping Europe and North America: a few people rested their hands on a table and, after a while, the table moved. Michael Faraday, the great experimenter at the Royal Institution, set out to find where the force came from.

He built a simple gadget: a light lever attached to a piece of cardboard lying on the table, with its long arm serving as a pointer. If the sitters' hands pushed sideways while the table stayed put, the pointer gave them away. When the sitters couldn't see the pointer, it wavered even though they insisted they were pressing straight down. Once they could watch it and see their own push, the effect stopped.

Faraday reported his result in a letter to The Times printed on June 30, 1853, and in a longer account in The Athenaeum on July 2: the table moved because of the sitters' own muscular pressure, applied without their knowing. He didn't accuse anyone of cheating. He showed that the body pushes before the mind notices.

What current research says

Psychologists still study ideomotor actions because they reveal something intriguing: the body sometimes expresses information the conscious mind can't put into words.

A University of British Columbia study, published in 2012 in Consciousness and Cognition by Hélène Gauchou, Ronald Rensink and Sidney Fels, had people answer yes-or-no general knowledge questions with a Ouija board. When participants felt they were only guessing, their spoken answers were at chance, while the answers they gave through the planchette were right more often.

The authors didn't conclude that the board had powers. They concluded that nonconscious knowledge can surface through small movements. It's a lab finding with clear limits, but it helps explain why a pendulum can seem to "know" something you haven't yet admitted to yourself.

Why the ideomotor effect makes the pendulum a mirror

The ideomotor effect means the pendulum doesn't bring in information from outside; it draws it out of you. What moves the chain is a blend of what you know, what you expect, what you fear and what you hope. That's why a pendulum can't predict events, yet it can show you very clearly which way you're leaning.

Treat each swing as a question handed back to you. If the pendulum says yes and you feel relief, that relief is telling you something. If it says yes and your chest tightens, that's worth noticing too. The swing is the prompt; the real answer is what you notice in your body when you see it.

Seen this way, using a pendulum is closer to journaling or thinking out loud than to consulting an oracle. You don't have to believe in hidden forces for it to help, and you don't have to give it up to respect the science.

See it for yourself

You can run a homemade version of Chevreul's test in a few minutes. You don't need any special equipment, just a pendulum or a ring on a thread.

On Paths, the "your hand" engine makes the same effect visible: you hold your phone like a pendulum, or the pendulum hangs from your mouse pointer on a computer, and your own micro-movements decide the answer.

• Hold the pendulum with your elbow in the air and think hard about "back and forth" without deliberately moving your hand. Watch what happens.
• Now rest your forearm and wrist on the table and try again. The swing usually shrinks.
• Ask a friend to hide a coin under one of two cups without telling you which, then ask the pendulum where it is. Write down the results over several rounds.
• Repeat with your eyes closed and compare how much the pendulum moves.

Talking about the ideomotor effect without judgment

Explaining the ideomotor effect isn't the same as calling anyone gullible. People who use a pendulum aren't moving it on purpose, and the feeling that it moves by itself is a real experience. What changes is the explanation for that experience.

Plenty of longtime pendulum users know about the effect and work with it: they calibrate their yes and no, ask questions that leave room for feeling, and take the answer as one more piece of information rather than an order. That's the way Paths invites you to use it.