The expression bicameral mind is indebted to the Latin words bi (two) and camera (room). It refers to the purported existence of two virtual rooms or compartments within the mind. The bicameral mind theory was formulated during the 1960s, and subsequently published in book form in 1976 by the American psychologist Julian Jaynes (1920-1997). It involves the hypothesis that ontogenetically, modern human consciousness might well originate from the breakdown of a primitive bicameral 'mind-space', and that hallucinations can therefore be interpreted as a sign of regression to that prior evolutionary stage. Jaynes speculates that the pre-conscious mentality characteristic ofindividuals in ancient cultures was consciously aware of endogenously mediated percepts, but not of their being mediated by the mind's own 'second chamber'. In this sense, Jaynes' theory may be seen as a conceptual precursor of today's *inner speech models of hallucinatory experience, notably the * defective corollary discharge model, which seeks to explain the misattribution of endogenous linguistic signals in individuals with * verbal auditory hallucinations (VAH) in terms of a failure in corollary discharge (or 'feedforward') signal that normally allows the brain's speech perception areas to recognize an incoming signal as 'its own'. Jaynes illustrates his bicameral mind thesis with numerous references to Homer (c. 750-c. 700 BC), who depicted the heroes of the Iliad as individuals devoid of self-awareness as we know it today. As a consequence, according to Jaynes, these individuals seldom referred to themselves, and seemed to lack the linguistic tools to express their own strivings and emotions. As Jaynes maintains, "In distinction to our own subjective conscious minds, we can call the mentality of the Myceneans a bicameral mind. Volition, planning, initiative is organized with no consciousness whatever and then 'told' to the individual in his familiar language, sometimes withthe visual aura ofafamiliarfriend orauthor-ity figure or 'god', or sometimes as a voice alone.The individual obeyed these hallucinated voices because he could not 'see' what to do by himself." Jaynes interpretes Homer's narrative style as a sign that the mind of the Myceneans was radically different from ours, i.e. that it lacked our present introspective, self-reflective nature, rendering it incapable of unmasking hallucinations as phenomena from within. As Jaynes suggests, "What triggered these hallucinations? I suggest it was even the slight stress ofmaking a decision in a novel circumstance, whereas in ourselves in modern times the stress threshold for such triggering of a verbal hallucination is much higher. The reason they are so prevalent in all cultures today, in the hospital patients and homeless..., in children and speechless quadriplegics, is because they were once the genetic basis of this ancient mentality, and the genes for this potentiality are still with us today. Verbal hallucinations, we think, evolved along with the evolution of language during the late Pleistocene as the response part of the brain register of all admonitory information. Its survival value at first was simply to direct an individual in various long-term tasks, which cued their occurrence. By 9000 BC, such voices were called what we call gods. The bicameral mind produced a new kind of social control that allowed agricultural civilizations to begin." Jaynes' bicameral mind hypothesis has been discarded and defended for many different reasons, but scientific interest in his work has been re-awakened by the consistent findings of right-sided activation patterns in the brain, as retrieved with the aid of neuroimag-ing studies in individuals with verbal auditory hallucinations.
References
Dierks, T., Linden, D.E.J., Jandl, M., Formisano, E., Goebel, R., Lanfermann, H., Singer, W. (1999). Activation of Heschl's gyrus during auditory hallucinations. Neuron, 22, 615-621.
Jaynes, J. (1976). The origin of consciousness in the breakdown of the bicameral mind. Boston, MA: Houghton Mifflin Company.
Kuijsten, M., ed. (2006). Reflections on the dawn of consciousness: Julian Jaynes's bicameral mind theory revisited. Henderson, NV: Julian Jaynes Society.
Sher, L. (2000). Neuroimaging, auditory hallucinations, and the bicameral mind. Journal of Psychiatry & Neuroscience, 25, 239-240.
Sommer, I.E.C., Aleman, A., Kahn, R.S. (2003). Left with the voices or hearing right? Later-alization of auditory verbal hallucinations in schizophrenia. Journal of Psychiatry and Neuroscience, 28, 17-18.