James Braid (surgeon) in the context of "Ideomotor phenomenon"

The ideomotor phenomenon is a psychological phenomenon wherein a subject makes motions unconsciously. Also called ideomotor response (or ideomotor reflex) and abbreviated to IMR, it is a concept in hypnosis and psychological research. It is derived from the terms "ideo" (idea, or mental 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 automatic muscular reaction, often of minuscule degree, and potentially outside of the awareness 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 of automatic writing, dowsing, facilitated communication, applied kinesiology, and ouija boards have been attributed to the phenomenon.

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 to James Braid's first neuropsychological explanation of the principle through which suggestion operated in hypnotism.