Hypnosis has been defined as "...a special psychological state with certain physiological attributes, resembling sleep only superficially and marked by a functioning of the individual at a level of awareness other than the ordinary conscious state." This definition captures our common understanding of hypnosis; however, research has not only revealed that hypnosis is a much more complicated thing, but it has also given rise to a number of definitions. One suggestion is that hypnosis is a mental state, while another links it to imaginative role-enactment.
Persons under hypnosis are said to have heightened focus and concentration with the ability to concentrate intensely on a specific thought or memory, while blocking out sources of distraction. Hypnosis is usually induced by a procedure known as a hypnotic induction involving a series of preliminary instructions and suggestions. The hypnotic suggestions may be delivered by a hypnotist in the presence of the subject, or may be self-administered ("self-suggestion" or "autosuggestion"). The use of hypnotism for therapeutic purposes is referred to as "hypnotherapy", while its use as a form of entertainment for an audience is known as "stage hypnosis".
The term "hypnosis" comes from the Greek word Hypnos which means sleep. The words "hypnosis" and "hypnotism" both derive from the term "neuro-hypnotism" (nervous sleep) coined by the Scottish surgeon James Braid around 1841. Braid based his practice on that developed by Franz Mesmer and his followers ("Mesmerism" or "animal magnetism"), but differed in his theory as to how the procedure worked.
There is a belief that hypnosis is a form of unconsciousness resembling sleep, but contemporary research suggests that hypnotic subjects are fully awake and are focusing attention, with a corresponding decrease in their peripheral awareness. Subjects also show an increased response to suggestions. In the first book on the subject, Neurypnology (1843), Braid described...