The creation of a distinct concept of hypnosis owes its existence mostly to a charismatic 18th century healer named Franz Anton Mesmer (1734-1815).
Mesmer had a deep interest in Paracelsan astrological principles, and the supposed direct influence of heavenly bodies on human health, by means of what were believed by Mesmer and others to be measurable physical forces (as opposed to the subtle forces of later occult doctrines interpreting Mesmerism).
Mesmer first applied magnets to patient's bodies in elaborate theatrical rituals that often resulted in expected spasmodic muscular contractions and collapse, and often the cure of various kinds of illness. Mesmer favored the rationalist views of his time, taking on terms like gravitation and magnetism to originally describe his theories of his healing work, and how the subtle fluids within the body could be influenced by him.
Mesmerism caught on widely, attracting followers to many spiritualist, religious, and scientific variations of mesmerism, as well as to 'mesmerism' as a dramatic form of entertainment for its own sake ('stage hypnosis').
It was highly influential in a number of popular movements, some of which are still very popular today.
The clearest transition between Mesmer's animal magnetism and modern therapeutic hypnosis was represented by Manchester surgeon James Braid, who coined the term hypnosis (from previous use by French researchers) in 1843. The term refers to Hypnos, the Greek god of sleep, because most forms of mesmerism at that time involved the production of an apparently sleep-like condition.
Braid, as many scientists and physicians before and after him, recognized in hypnosis certain legitimate psychological phenomena of interest, but requiring much more systematic investigation to understand. Mesmer had come to believe that it was not physical forces via magnets but he himself that was producing the cures he produced. Others not long after Mesmer soon began to suspect that the human imagination played a much larger role in the process than did any physical forces or capacities of the mesmerist. This was important, because mesmerism went through a number of periods of great disrepute due to associations with occultism and various kinds of blatant charlatanism.
A split arose between those interested in hypnosis as a subject of scientific investigation and as an adjunct to medical treatment, and those who considered it a tool for personal or spiritual fulfillment, or for esoteric investigations of religious or 'magical' nature. Faith healing, mind cure, and Christian Science were all heavily influenced by hypnosis, and derived much of their impetus in the late 19th century from the reputation of Mesmer and later mesmerists. Various followers of the highly influential Theosophical Society and of the Hermetic Order of the Golden Dawn magical fraternity found great affinity for the magnetic theories of mesmerism, which they often interpreted in a semi-metaphorical way rather than as literal electromagnetism.
In the early scientific study, Braid at first thought that hypnotic induction would yield a unique condition of the nervous system that was linked somehow to certain cures by suggestion. He later rejected this, and other physiological explanations of hypnosis, and emphasized "mental" factors almost exclusively. The theory of neural inhibition has never been completely rejected as applicable, however, though often considered insufficient by itself. Ivan Pavlov later greatly expanded on the neural inhibition theory in his concept of the physiology of sleep (as a progressive cortical inhibition, which turns out to be fairly accurate - in general if not in detail).
This neurological explanation of hypnosis was strongly rejected by Charcot, who believed that the best hypnotic subjects were 'hysterics,' and that hypnosis was therefore a manifestation of what was then considered the mental illness of hysteria. His belief turned out to be wrong, and his view of hysteria as a distinct mental illness as well, and his psychopathological view was rejected by the end of the 19th century. Two legacies of the neurological pathological theories of Charcot and the so-called "Paris school" of hypnosis that have endured are cortical inhibition theory and the later development of dissociation theory, though neither one serves as a complete theory of hypnosis on its own.
In the early 20th century, the foundation for most hypnotic theory was laid by the members of the so-called "Nancy school" of hypnosis (such as Liebault and Bernheim) who elaborated a theory of hypnotic suggestion based onideomotor action.
This theory had eventually replaced not only the early neuro-pathological view, but also Braid's early psychological theory, "monoideism," the theory that un-conflicted ideas automatically lead to actions. Ideomotor action theory says that ideas suggested by the hypnotist lead automatically to actions, which are then experienced by the subject as unwilled. Ideomotor action is another example of a useful but incomplete model of hypnotic responding. The Nancy school was perhaps most notable in their de-emphasis of hypnotic ritual and their strong emphasis on suggestion as a mundane though useful psychological process.
Sigmund Freud had originally studied under Charcot and had a deep interest in hypnosis for much of his life. In 1889, he shifted from Charcot's view to that of the Nancy school's emphasis on suggestion rather than hysteria, believing that patients often remembered repressed memories in a beneficial process under hypnosis. Freud was reportedly a very poor hypnotist, being limited to a simple authoritarian style of induction, and in 1896, he rejected hypnotic induction ritual as unnecessary and too likely to foster unwanted amorous advances by patients ('transference,' and the theory of hypnosis as an eroticized dependent relationship). Freud replaced the hypnotic procedure with simply placing his hand on the subject's forehead to help establish what he believed was the proper social relationship of doctor in dominance over patient.
What qualified acceptance of hypnosis in medicine that we have today is largely due to the efforts of pioneers in the experimental study of hypnosis, starting in the 1920's and 30's. Foremost early researchers were Clark Hull and his then student, Milton Erickson. Hull's 1933 discussion of scientific research into hypnosis (Hypnosis and Suggestibility) is still considered a classic.
Erickson later came to disagree with Hull on the important issue of fundamental approach, stressing the complex subjective inner processes operating in hypnosis, rather than the measurable correlates and standardized procedures promoted by Hull. Hull went on to make important contributions in learning theory, while Erickson went on to become the name most closely associated with clinical hypnosis today.
Milton Erickson died in 1980, but left a legacy of often zealous followers, a number of important contributions to the field, and several offshoot schools of applied psychology based on his core principles of indirect strategic therapy and suggestion, and based on hypothetical unconscious processes and indirect forms of human communication. Examples include Jay Haley's strategic model of therapy, the MRI Interactional model, the Erickson-Rossi hypnotic theories, Neurolinguistic Programming (NLP), and a number of later frameworks such as that of Lankton (1983) and Gilligan (1987). The 'Ericksonian' models deliberately blur the traditional distinction between hypnosis and other forms of therapy, and share this basic idea with the 'skeptical' view of hypnosis, which we will consider in the next section.
In addition to Erickson and Hull, modern scientific research into hypnosis is often associated with a period of intense experimental research in the late 1950's and early 1960's by notables such as J.P Sutcliffe, T.X. Barber, M.T.Orne, E.R. Hilgard, R.E. Shor, and T.R. Sarbin. The work of these researchers had been particularly influential on the current scientific view of hypnosis, especially as viewed in medicine.