Ideomotor
The ideomotor effect is movement begun by an idea — a thought, an image, an expectancy — without a felt decision to move. The Chevreul pendulum swinging when you only imagine "left." Fingers that part on a yes. A head that nods before the mouth has agreed. The body voting quietly.
It is the most honest instrument in the room. It is also the most stolen by people who want a pendulum to fetch the future.
The long walk, including Chevreul, is in the ideomotor effect. This page is the noun.
What it is not
It is not a spirit. It is not the unconscious sending mail. It is not proof that "the body knows a hidden truth" and is ready to confess it. An ideomotor signal tells you that an idea has reached the muscles. It does not tell you the idea is correct, deep, or kind.
It is not the same as catalepsy. Catalepsy is a hold. Ideomotor is a start.
It is not a lie detector and not a diagnosis. Finger-sign systems ("this finger for yes") are useful as conversation with the body in front of you. They are worthless as archaeology of someone else's childhood.
How it is actually used
As a convincer. The pendulum, the magnetic fingers, the heavy book in the palm — tiny, harmless movements the person did not micromanage. After that, the question "does this work on me?" is no longer abstract. That is why learning hypnosis starts here and not at the induction.
As a channel. In a session, a finger-yes or a small nod is often cleaner than asking "are you under?" Asking hauls them up. Watching the channel lets them stay.
As a test of the room. If nothing moves, you do not shout. You change the size of the ask, or you believe the no. Forcing a pendulum is how you teach someone to fake for you.
Suggestion uses the same pipe: an idea, a little expectancy, a body willing to try it. Ideomotor is that pipe with the tap open just enough to see water.
Where the claims stop
A swinging weight will follow imagination. That is enough. It will not find your lost keys, name your trauma, or pick a stock. The moment you ask it to be an oracle, you have left the craft.
Between adults, the same quiet vote is how you notice a trigger landing, or a no that has not yet become a word. That is consent with the volume down — not a replacement for the word.
See also
The ideomotor effect · Catalepsy · Suggestion · Hypnosis pendulum · Suggestibility
FAQ
What is the ideomotor effect? Movement started by an idea rather than by a felt decision. Pendulums, yes-fingers, unplanned nods.
Does a moving pendulum mean I am hypnotised? It means an idea reached your hands. That is a foot in the door, not the whole house.
Are ideomotor signals always true? They are true as signals. They are not true as facts about the world. A yes-finger can mean yes, or please, or I want this over.
Is Chevreul's pendulum a hypnosis induction? It can become one. By itself it is a waking test of the same pipe induction later uses.