The first neuro-psychological theory of hypnotic suggestion was introduced early on by James Braid who adopted his friend and colleague William Carpenter's theory of the ideo-motor reflex response to account for the phenomenon of hypnotism. Carpenter had observed from close examination of everyday experience that under certain circumstances the mere idea of a muscular movement could be sufficient to produce a reflexive, or automatic, contraction or movement of the muscles involved, albeit in a very small degree. Braid extended Carpenter's theory to encompass the observation that a wide variety of bodily responses, other than muscular movement, can be thus affected, e.g., the idea of sucking a lemon can automatically stimulate salivation, a secretory response. Braid therefore adopted the term "ideo-dynamic", meaning "by the power of an idea" to explain a broad range of "psycho-physiological" (mind-body) phenomena. Braid coined the term "mono-ideodynamic" to refer to the theory that hypnotism operates by concentrating attention on a single idea in order to amplify the ideo-dynamic reflex response. Variations of the basic ideo-motor or ideo-dynamic theory of suggestion have continued to hold considerable influence over subsequent theories of hypnosis, including those of Clark L. Hull, Hans Eysenck, and Ernest Rossi. It should be noted that in Victorian psychology, the word "idea" encompasses any mental representation, e.g., including mental imagery, or memories, etc. Source Wikipedia