Ernest Hilgard refers to the most prominent advocate of altered state of conciousness in hypnosis. Hildgard in 1986 put forward a Neo-dissociation theory. According to this theory, th ere is a dissociation or division of conciousness into separate channels of mental activity in hypnosis. This dissociation or division allows the person to focus his attention hypnotist and, simultaneously, enable is to perceive other events peripherally or subconciously.