Using EEGs, the doctors were able to ascertain that the brain activity normally associated with sight wasn't present while a blind alter was in control of the woman's body, even though her eyes were open. Remarkably, when a sighted alter assumed control, the usual brain activity returned.
This was a compelling demonstration of the literally blinding power of extreme forms of dissociation, a condition in which the psyche gives rise to multiple, operationally separate centers of consciousness, each with its own private inner life.
Modern neuro-imaging techniques have demonstrated that DID is real: in a 2014 study, doctors performed functional brain scans on both DID patients and actors simulating DID. The scans of the actual patients displayed clear differences when compared to those of the actors, showing that dissociation has an identifiable neural activity fingerprint. In other words, there is something rather particular that dissociative processes look like in the brain.
There is also compelling clinical data showing that different alters can be concurrently conscious and see themselves as distinct identities. One of us has written an extensive treatment of evidence for this distinctness of identity and the complex forms of interactive memory that accompany it, particularly in those extreme cases of DID that are usually referred to as multiple personality disorder...read more>>>...
