intensity. It is the same with differentiation-dissociation. Disorders such as dissociative identity disorder are often in the extreme end of the continuum that begins with normal differentiation. It is a matter of intensity. Therefore, the general principle of personality formation in which the process of separation has resulted in discrete segments, called ego states, with boundaries that are more or less permeable. Where however an ego state is a response to psychological trauma, it may remain completely walled-off from the rest of the personality. Ego states exist as a collection of perceptions, cognitions and affects in organised clusters. An ego state may be defined as an organized system of behavior and experience, whose elements are bound together by common principle. When one of these states is invested with ego energy, it becomes "the self" in the here and now. This state is executive, and experiences the other states which are then invested with object energy. Ego states vary in their volume. A large ego state may include all the various behaviors activated in one's occupation. A small ego state are the behaviours one experiences in a simple action, such as using a mobile phone. They may represent current modes of behavior and experiences or, as with hypnotic age regression, include many memories, postures, feelings, etc. that were apparently learned at an earlier age. They may be organised into different dimensions. For example, an ego state may be built around the age of 10. Another one may represent patterns of behavior toward a father or authority figures and thus overlap with experiences from the age of 10. Behaviors to accomplish a similar goal may be uniquely different from one ego state to another, especially in true multiple personalities. 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