Hypnosis (from the Greek hypnos, “sleep”) is “a trance-like state that resembles sleep but is induced by a person whose suggestions are readily accepted by the subject.”
The technique is used for medical purposes to relieve anxiety or otherwise improve or alter behaviour. It is also used in popular stage acts in which subjects are persuaded to perform bizarre feats.
Other variations include mass-hypnosis, in which crowds are simultaneously influenced, and autosuggestion in which a subject persuades themself.
Hypnotic susceptibility is the measurable responsiveness that a person has to hypnosis. Not all people can be hypnotized, but about 10% of people respond exceptionally well.
There is little evidence linking susceptibility to intelligence or personality traits, but some research has linked hypnosis to the amount of imagination in subjects. Recent research suggests that highly hypnotizable people have high sensory and perceptual gating abilities that allow them to block some stimuli from awareness.
There is a common claim that no one can be hypnotized against their will.
New research, developed by board-certified hypnotist Gerald Kein, claims that everybody is equally hypnotizable and that “people accept hypnosis in direct relationship to the amount of fear they have”. Successful hypnosis is attained by the removal of inhibitory fear. With fear removed, most individuals can be deeply hypnotized in 5-10 seconds. Licensed mental health professionals are generally not trained in these techniques and use the old Progressive Relaxation (PR) hypnotic induction developed in the 1940s.