HOW COMMON ARE THESE BEHAVIORS?
The frequency of multiple personality has been debated over time. While some descriptions of these behaviors occurred early in the 20th century, but from the 1920s to the early 1970s, there was a marked deficit of cases (Spanos, 1994). Kohlenberg (1973) termed these behaviors as being “relatively rare” as did Caddy (1985); other reports saw it as very numerous in number late in the last century. For instance there were more cases reported from the mid-1970s to the mid-1980s than in the previous two hundred years (Orne, Dinges, & Orne, 1984). Curiously, the substantial increase in reported cases has occurred almost exclusively in North America. This behavior pattern is rarely diagnosed in the United Kingdom, France, and Russia; no case has ever been reported in Japan (Spanos). In North America, the bulk of reported diagnoses is made by a small minority of professionals. Most professionals go through an entire career and rarely if ever see such behaviors, (Mersky, 1992; Modestin, 1992; Spanos).
The dramatic increase in the reported numbers of cases has been attributed to differing factors. Possibly, cases which were un-diagnosed in previous decades are now being diagnosed due to greater vigilance for these behaviors; it has also been proposed that the label is being applied (and over-diagnosed) to individuals whose behaviors are readily suggestible (American Psychiatric Association, 1994). One can reasonably conclude that the prevalence of Dissociative Identity Disorder was disputed in the late 20th century and still is disputed. Some readers may also dispute the validity of this diagnosis as the DSM-IV, unlike earlier versions of the DSM, does not provide any diagnostic reliability information, (American Psychiatric Association, 1994). Hopefully the up-coming DSM-V will clarify the situation.
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