The Dissociative Taxon and Dissociative Identity Disorder.

A total of 491 participants from four previous studies, 443 of whom were diagnosed with dissociative identity disorder (DID) on the Dissociative Disorders Interview Schedule, completed the Dissociative Experiences Scale (DES). Their results were analyzed to determine how many were in the dissociative taxon (DES-T) on the DES. Of the 443 individuals with DID, 419 (94.6%) were in the taxon, 13 (2.9%) were out of the taxon and 11 (2.5%) were indeterminate. The DES-T is therefore very effective at identifying people with DID as being in the dissociative taxon, although it does have a false negative rate of 5.4%. Out of 48 people with no dissociative disorder on the Dissociative Disorders Interview Schedule, the DES-T identified 26 (54.2%) as being in the taxon and 22 (45.8%) as being out of the taxon with no indeterminate cases. The clinical diagnoses of these 48 individuals are unknown: all were inpatients in the same Trauma Program. Thus, the sensitivity of the DES-T for confirming that individuals with DID are in the dissociative taxon was 94.6% and the specificity of the DES-T for confirming that individuals with no dissociative disorder are not in the dissociative taxon was 45.8%. It is possible that the DES-T yields false positives for taxon membership; this possibility should be investigated in future research.