Dissociative states in multiple personality disorder: a quantitative study.

Multiple personality disorder (MPD) patients may experience themselves as several discrete alter personalities who do not share consciousness or memories with one another. In this study, we asked whether MPD patients are different from controls in their ability to learn and remember, and their ability to compartmentalize information. MPD patients were not found to differ from controls in overall memory level. Learning of information by MPD patients in disparate personality states did not result in greater compartmentalization than that of which control subjects were capable. However, there were qualitative differences between the cognitive performance of patients and that of controls attempting to role-play alter personalities. Our results suggest that simple confabulation is not an adequate model for the MPD syndrome, and we consider a possible role for state-dependent learning in the phenomenology of MPD.