Hypnosis
Hypnosis is a process to assist focus and dissociation. Through hypnosis, the therapist can focus on a single ego state or segment of personality and dissociate other parts. Many practitioners today are hypnotically activating covert ego states and announcing that they have discovered another multiple personality. Although multiple personalities are usually studied through hypnosis, they should be diagnosed only when the ego states can become overt spontaneously and when the main personality is generally amnesic to what occurs when the alter is overt and executive. When a covert ego state can be induced to emerge only through hypnosis, we do not consider this as a true multiple personality, and it should not be diagnosed. Ego states are commonly found through student volunteers for hypnotic studies. Because hypnosis is a form of dissociation, it is not surprising to find that good hypnotic subjects often manifest covert ego states in their personalities without being mentally ill.
Read more about this topic: Ego-state Therapy