A psychoneurotic reaction in which a portion of experience is split off, or isolated, from conscious awareness.As a neurotic reaction, dissociation is an unconscious attempt either (1) to protect the self from distressing and threatening impulses and events; or (2) to gain expression for forbidden desires without paying the penalty of guilt or anxiety. Dissociative reactions were at one time classified as one type of hysteria, the other being conversion reactions, in which emotional conflicts are expressed as bodily symptoms. Although the dynamics of the two disorders are similar, they are classified separately today.There are four primary kinds of dissociative reactions: amnesia, fugue,dual personality, and somnambulism. In some types of amnesia, the individual protects himself from distasteful experiences by an unconscious process of repression, or forgetting. In the fugue state, he obeys an unconscious urge to flee from a distressing situation,and afterward has no recollection of what he did during the episode. In dual or multiple personality, he gives expression to repressed urges by unconsciously assuming more than one identity. In somnambulism he expresses forbidden impulses and feelings through actions carried out during sleep.All these reactions are unconscious attempts to solve problems with a divided mind which keeps conflicting ideas and impulses apart. Aside from somnambulism, dissociative reactions comprise less than 5 per cent of psychoneurotic disorders today.