Post-hypnotic suggestion

Hypnosis is a state of human consciousness involving focused attention and reduced peripheral awareness and an enhanced capacity to respond to suggestion. The term may also refer to an art, skill, or act of inducing hypnosis.

Theories explaining what occurs during hypnosis fall into two groups. Altered state theories see hypnosis as an altered state of mind or trance, marked by a level of awareness different from the ordinary conscious state. In contrast, nonstate theories see hypnosis as a form of imaginative role-enactment.

During hypnosis, a person is said to have heightened focus and concentration. The person can concentrate intensely on a specific thought or memory, while blocking out sources of distraction. Hypnotised subjects are said to show an increased response to suggestions. Hypnosis is usually induced by a procedure known as a hypnotic induction involving a series of preliminary instructions and suggestion. 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". Stage hypnosis is often performed by mentalists practicing the art form of mentalism.

The term "hypnosis" comes from the ancient Greek word ὕπνος hypnos, "sleep", and the suffix -ωσις -osis, or from ὑπνόω hypnoō, "put to sleep" (stem of aorist hypnōs-) and the suffix -is. The words "hypnosis" and "hypnotism" both derive from the term "neuro-hypnotism" (nervous sleep), all of which were coined by Étienne Félix d'Henin de Cuvillers in 1820. These words were popularized in English by the Scottish surgeon James Braid (to whom they are sometimes wrongly attributed) around 1841. Braid based his practice on that developed by Franz Mesmer and his followers (which was called "Mesmerism" or "animal magnetism"), but differed in his theory as to how the procedure worked.

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