People often think Jaynes’ bicameral control hypothesis is imaginative yet implausible as an actual mechanism of cognitive control. Well, if you look at the research on schizophrenic voice hearing, it becomes quite clear that bicameral control is a reality for a small percentage of the population.
Fowler et al have noted that, in those who have experienced trauma, auditory verbal haclluinations (AVHs) typically involve critical comments or comments about the person’s day-to-day experiences. This observation is consistent with the conclusion of a study of AVH phenomenology in patients with schizophrenia and in those without any psychiatric diagnoses, by Leudar et al.This study concluded that AVHs are “focused on the regulation of everyday activities” (p. 896). Similarly, Nayani and David note that 46% of their sample of patients with schizophrenia said their AVHs had come to replace their “voice of conscience” (p. 185) and that a proportion relied on their AVH for making decisions. (link)
Here we have a perfectly clear clinical example of bicameral control. Such patients have subconsciously authorized the auditory verbal hallucinations (AVH) to control their behavior in times of decision making. The same process of authorization is also evident in hypnosis. The hypnotized person will authorize the hypnotist to automatically control their behavior with verbal commands. With hypnosis, the voice is everything; it is the direct link to the behavior of hypnotized person. AVHs are simply this process but internalized by means of stored admonitory wisdom. In times of decision making or stress, the stored admonitory wisdom is triggered and experienced as an AVH. The internal commands and judgements serve to control behavior by means of linguistic self-regulation. This is something normal people can do through conscious inner speech mechanisms. The neural code of language is capable of representing patterns of action that can control behavior when neurally active. These would be stored in terms of what cognitive scientists called “action-oriented representations”. We can quite literally “tell ourselves what to do”. It is the same with AVH except that instead of conscious inner speech we have subconscious admonitory wisdom stored in terms of a personality (usually a social authority) that is capable of commanding, judging, critiquing, guiding, cursing, etc. So, far from being simply an imaginative hypothesis based on speculation, the bicameral control hypothesis is actually grounded on sound neuropsychological observation and self-reports.