WHAT IS MULTIPLE PERSONALITY?
The behavior pattern commonly known as Multiple Personality Disorder but now called Dissociative Identity Disorder (American Psychiatric Association, 1994) might be considered only a recent phenomenon. This behavior, however, was described in every DSM system since its inception (American Psychiatric Association, 1952, 1968, 1980, 1987, 1994); in addition, Flournoy (1900) described similar behaviors at the turn of the century. With a liberal interpretation, the self-report of the Biblical demoniac in Mark resembles those of multiple personalities: "my name is legion, for we are many," indicating that these behaviors are possibly ancient.
The diagnostic literature shows the definition of multiple personality as changing markedly over the editions of the Diagnostic and Statistical Manual of Mental Disorders. In the DSM-I, these behaviors were termed Dissociative reaction, (American Psychiatric Association, 1952), which came to be called Hysterical neurosis, dissociative type in the DSM-II (American Psychiatric Association, 1968). In each of these, multiple personality was not viewed as a discrete disorder but was grouped with somnambulism, amnesia, and fugue states. Only in the DSM-III does Multiple Personality Disorder appear as a separate diagnostic category, with a description of this behavior. This disorder's defining features were proposed being "the existence within the individual of two or more distinct personalities, each of which is dominant at a particular time," (American Psychiatric Association, 1980, p. 257). The DSM-IIIR of 1987 gave nearly identical defining features as "the existence within the individual of two or more distinct personalities or personality states," (American Psychiatric Association, 1987, p. 269). The defining features evolved further in the DSM-IV where this behavior pattern came to be termed Dissociative Identity Disorder. Its features became, "the presence of two or more distinct identities or personality states that recurrently take control of behavior," (American Psychiatric Association, 1994, p. 484). Both the 1980 and the 1994 definition bear close resemblance to defining features of individuals with behavioral repertoires referred to as “mediums,” “channelers” and “psychics,” (Hines, 1988; Spanos, 1994). In these latter three categories however, the differential personality repertoires, the differential self-report, and the differential remembering are under the control of more obvious public discriminative antecedents.
The subtle change in the 1994 definition is notable; distinct personalities were no longer seen as existing within the person or as a part of the person, but the behaviors displayed different states or conditions. This definition is less organismic or person-centered and more behavioral-environmental in theory than earlier versions. With the reader’s indulgence, the personality is behavior with variations or as "topographical subdivisions of behavior, occasioned by discriminative stimuli and controlled by reinforcement contingencies." A person whose behavior is consonant with this diagnostic label displays a personality showing more variability than that of the "average or normal" individual; the individual lacking one coherent personality displays a personality repertoire which is very divergent, with large variation in the contingencies between antecedents and responses. The antecedents, i.e., people, places, events, etc., of the individual in question occasion more responses of an idiosyncratic nature which are maintained by reinforcement contingencies singular to that individual. Along this approach, one writer took the new definition to mean that the individual displaying these behaviors could no longer be described as having more than one personality. Instead, the person should be viewed as having less than one whole, coherent personality (Sapulsky, 1995). Likewise Kohlenberg & Tsai (1991) reported that such individuals might not have acquired all the characteristics of a stable, singular personality.