Schizophrenia Voices

 50-Year-Old Theory on Schizophrenia's "Voices" Confirmed by Recent Study at Science Alert. 

"In healthy people, using inner speech produces the same kind of reduction in brain activity as when they speak out loud," Whitford says. "But in people who hear voices, that reduction of activity doesn't happen. In fact, their brains react even more strongly to inner speech, as if it's coming from someone else. That might help explain why the voices feel so real."

Underlying study from  University of New South Wales Sydney, patients from Sydney and Hong Kong

This has long been believed anecdotally by people who have heard lots of schizophrenics relate what voices are telling them. Auditory hallucinations can vary quite a bit, and focusing on an individual can lead one to leap to conclusions, which is why hallucinations in literature do not fit this pattern well. But hearing a thousand versions reveals a common pattern of voices accusing them of what they fear most, or explaining to them what they have already believed. A striking example was a patient of mine who had a severely disabled nonverbal son who required a great deal of care. After his wife died he gradually developed the idea that the young man was communicating to him mentally that he hated his life and wanted to die.  The impression became overwhelming, and he eventually killed him. It is not difficult to see that this was his own wish projected onto his son.

The method they set up to test the idea was clever.  The result reminded me very much of unshakeable delusions that schizophrenics can have, now narrowed down to a brain inability to compare one narrative against another simultaneously, so that new data and explanations cannot be held firmly in the mind, and the installed narrative cannot be dislodged. The lack of brainwave answer for internal versus external speech seems similar.