People with dissociative identity disorder (DID) and schizophrenia-spectrum disorders (SSD) both hear voices, but the experiences differ in key ways. DID participants reported voices as more internally located and generated, louder, and less controllable, and they endorsed more thought disorder symptoms. After accounting for sex, depersonalization, and childhood maltreatment, differences in voice loudness and controllability disappeared, but the DID group still reported more internal origin and derailment. The SSD group reported more distress, metaphysical beliefs about voices, incoherent thoughts, and word substitution. These latter features may reflect more psychotic processes.
Dissociative identity disorder (DID) is characterized by distinct identity states, each with its own sense of self, but whether these states provide a continuous self over time (diachronic unity) had not been studied. This study assessed diachronic disunity in 14 adults with DID (in both adult and child identity states), 19 adults with psychosis, 55 general-population adults, 26 general-population children, and 23 adults imagining themselves as children. Diachronic disunity appeared to some degree in all groups, not only psychiatric samples. DID adults reported more dissociation and self-confusion than psychosis and adult comparison groups but did not differ on the diachronic measure.