https://en.wikipedia.org/wiki/Bicameral_mentality

> Jaynes uses "bicameral" (two chambers) to describe a mental state in which the experiences and memories of the right hemisphere of the brain are transmitted to the left hemisphere via auditory hallucinations.

[snip]

> According to Jaynes, ancient people in the bicameral state of mind experienced the world in a manner that has some similarities to that of a person with schizophrenia. Rather than making conscious evaluations in novel or unexpected situations, the person hallucinated a voice or "god" giving admonitory advice or commands and obey without question: One was not at all conscious of one's own thought processes per se. Jaynes's hypothesis is offered as a possible explanation of "command hallucinations" that often direct the behavior of those with first rank symptoms of schizophrenia, as well as other voice hearers.