Case of apparent blindness proves multiple personality is not cultural or therapeutic artifact or metaphor: Alternate personalities are neurological.

“We present the case of a patient having dissociative identity disorder [multiple personality] who — after 15 years of misdiagnosed cortical blindness — step by step regained sight during psychotherapeutic treatment…

“In addition to its implications for the brain’s ability to control the inflow of visual information, the present case bears on discussions of the ontology of dissociative identity disorders [multiple personality]. In the literature on consciousness and the nature of the self, dissociative identity disorder has been taken as important evidence for the formulation of a scientific theory of the self. However, questions regarding the validity of the phenomenon have complicated the picture. From the onset, nosological description of dissociative identity disorders has been accompanied by an ongoing controversy about whether this disorder might be a cultural and therapeutic artifact. Recent psychobiological evidence has shown that different personality states are correlated with differing cortical activation patterns and has demonstrated neural correlates of switching between personality states. Yet that would still be compatible with a skeptical view that personality states are just metaphors reflecting differences in higher-level cognitive processing, or viewpoints that personality states result from therapeutic suggestions or elaborate forms of role playing. The case of BT contributes to this controversy by demonstrating that differences between personality states are not limited to higher level processing but can differ with respect to the fundamental processing of early sensory information and corresponding perceptual change. It therefore provides compelling evidence for the existence of the dissociated identities in a more biological sense” (1).

1. Hans Strasburger, Bruno Waldvogel. “Sight and blindness in the same person.” PsyCh Journal 4 (2015): 178–185. http://hans-strasburger.userweb.mwn.de/reprints/strasburger_waldvogel_2015_preprint.pdf