In 2015, doctors in Germany reported the extraordinary case of a woman who suffered from what has traditionally been called “multiple personality disorder” and today is known as “dissociative identity disorder” (DID). The woman exhibited a variety of dissociated personalities (“alters”), some of which claimed to be blind. 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.
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