Bicameralism (the philosophy of "two-chamberedness") is a hypothesis in psychology that argues that the human brain once assumed a state in which cognitive functions were divided between one part of the brain which appears to be "speaking", and a second part which listens and obeys—a bicameral mind. The term was coined by psychologist Julian Jaynes, who presented the idea in his 1976 book The Origin of Consciousness in the Breakdown of the Bicameral Mind, wherein he made the case that a bicameral mentality was the normal and ubiquitous state of the human mind only as recently as 3000 years ago.
Brain hemispheres and bicamerality 
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Julian Jaynes saw bicamerality as primarily a metaphor. He used governmental bicameralism 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. The metaphor is based on the idea of lateralization of brain function although each half of a normal human brain is constantly communicating with the other through the corpus callosum. The metaphor is not meant to imply that the two halves of the bicameral brain were "cut off" from each other but that the bicameral mind was experienced as a different, non-conscious mental schema wherein volition in the face of novel stimuli was mediated through a linguistic control mechanism and experienced as auditory verbal hallucinations.
The bicameral mentality would be non-conscious in its inability to reason and articulate about mental contents through meta-reflection, reacting without explicitly realizing and without the meta-reflective ability to give an account of why one did so. The bicameral mind would thus be a "zombie mind" lacking metaconsciousness, autobiographical memory and the capacity for executive "ego functions" such as deliberate mind-wandering and conscious introspection of mental content. When bicamerality as a method of social control was no longer adaptive in complex civilizations, this mental model was replaced by the conscious mode of thought which, Jaynes argued, is grounded in the acquisition of metaphorical language learned by exposure to narrative practice.
Jaynes' case for bicameralism 
According to Jaynes, ancient people in the bicameral state of mind would have experienced the world in a manner that has some similarities to that of a schizophrenic. Rather than making conscious evaluations in novel or unexpected situations, the person would hallucinate a voice or "god" giving admonitory advice or commands and obey without question: one would not be at all conscious of one's own thought processes per se. Research into "command hallucinations" that often direct the behavior of those labeled schizophrenic, as well as other voice hearers, supports Jaynes's predictions.
Jaynes built a case for this hypothesis that human brains existed in a bicameral state until as recently as 3000 years ago by citing evidence from many diverse sources including historical literature. He took an interdisciplinary approach, drawing data from many different fields. Jaynes asserted that, until roughly the times written about in Homer's Iliad, humans did not generally have the self-awareness characteristic of consciousness as most people experience it today. Rather, the bicameral individual was guided by mental commands believed to be issued by external "gods" — commands which were recorded in ancient myths, legends and historical accounts. This is exemplified not only in the commands given to characters in ancient epics but also the very muses of Greek mythology which "sang" the poems: the ancients literally heard muses as the direct source of their music and poetry.
For example, in the Iliad and sections of the Old Testament no mention is made of any kind of cognitive processes such as introspection, and there is no apparent indication that the writers were self-aware. According to Jaynes, the older portions of the Old Testament (such as the Book of Amos) have few or none of the features of some later books of the Old Testament (such as Ecclesiastes) as well as later works such as Homer's Odyssey, which show indications of a profoundly different kind of mentality — an early form of consciousness. However the Epic of Gilgamesh, considered by many historians to be the oldest known recorded story (ca. 2000-2100 BC), features characters whose actions are deeply rooted in introspection and dream analysis.[original research?]It can be argued in turn that many distinct sources for the epic are known from over a 2,000-year timeframe, and earlier versions now lost may have been consistent with Jaynes model.
In ancient times, Jaynes noted, gods were generally much more numerous and much more anthropomorphic than in modern times, and speculates that this was because each bicameral person had their own "god" who reflected their own desires and experiences. He also noted that in ancient societies the corpses of the dead were often treated as though still alive (being seated, dressed and even fed) and argued that the dead bodies were presumed to be still living and the source of auditory hallucinations (see ancestor worship). This adaptation to the village communities of 100 individuals or more formed the core of religion. Unlike today's hallucinations, the voices of ancient times were structured by cultural norms to produce a seamlessly functioning society. In Ancient Greek culture there is often mention of the Logos, which is a very similar concept. It was a type of guiding voice that was heard as from a seemingly external source.
Jaynes inferred that these "voices" came from the right brain counterparts of the left brain language centres—specifically, the counterparts to Wernicke's area and Broca's area. These regions are somewhat dormant in the right brains of most modern humans, but Jaynes noted that some studies show that auditory hallucinations correspond to increased activity in these areas of the brain.
Even in modern times, Jaynes notes that there is no consensus as to the cause or origins of schizophrenia (the subject is still hotly debated). According to Jaynes, schizophrenia is simply a vestige of humanity's earlier state. Recent evidence shows that many schizophrenics don't just hear random voices but experience "command hallucinations" instructing their behavior or urging them to commit certain acts. As support for Jaynes's argument, these command hallucinations are little different from the commands from gods which feature so prominently in ancient stories. Indirect evidence supporting Jaynes's theory that hallucinations once played an important role in human mentality can be found in the recent book Muses, Madmen, and Prophets: Rethinking the History, Science, and Meaning of Auditory Hallucination by Daniel Smith.
Breakdown of bicameralism 
Jaynes theorized that a shift from bicameralism marked the beginning of introspection and consciousness as we know it today. According to Jaynes, this bicameral mentality began malfunctioning or "breaking down" during the second millennium BC. He speculates that primitive ancient societies tended to collapse periodically, (as in Egypt's Intermediate Periods and the periodically vanishing cities of the Mayas) as changes in the environment strained the socio-cultural equilibria sustained by this bicameral mindset. The mass migrations of the second millennium BC, caused by Mediterranean-wide earthquakes, created a rash of unexpected situations and stresses that required ancient minds to become more flexible and creative. Self-awareness, or consciousness, was the culturally evolved solution to this problem. This necessity of communicating commonly observed phenomena among individuals who shared no common language or cultural upbringing encouraged those communities to become self-aware to survive in a new environment. Thus consciousness, like bicamerality, emerged as a neurological adaptation to social complexity in a changing world.
Jaynes further argues that divination, prayer and oracles arose during this breakdown period, in an attempt to summon instructions from the "gods" whose voices could no longer be heard. The consultation of special bicamerally operative individuals, or of casting lots and so forth, was a response to this loss, a transitional era depicted for example in the book of 1 Samuel. It was also evidenced in children who could communicate with the gods, but as their neurology was set by language and society they gradually lost that ability. Those who continued prophesying, being bicameral according to Jaynes, could be killed. Leftovers of the bicameral mind today, according to Jaynes, include religion, hypnosis, possession, schizophrenia and the general sense of need for external authority in decision-making.
The idea that language is a necessary component of subjective consciousness and more abstract forms of thinking has been gaining acceptance in recent years, with proponents such as Andy Clark, Daniel Dennett, William H. Calvin, Merlin Donald, John Limber, Howard Margolis, Peter Carruthers, and José Luis Bermúdez. Philosopher Gary Williams has recently defended Julian Jaynes against Ned Block's criticisms in the journal Phenomenology and the Cognitive Sciences.
A collection of Jaynes's essays on bicameralism combined with those of contemporary scholars was published in 2007, in a book titled Reflections on the Dawn of Consciousness: Julian Jaynes's Bicameral Mind Theory Revisited. Included in this book is new support for Jaynes's theory by Marcel Kuijsten, psychological anthropologist Brian J. McVeigh, psychologists John Limber and Scott Greer, clinical psychologist John Hamilton, philosophers Jan Sleutels and David Stove, and sinologist Michael Carr (see shi "personator"). The book also contains an extensive biography of Julian Jaynes by historian of psychology William Woodward and June Tower, and a Foreword by neuroscientist Michael Persinger.
Critical responses 
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Richard Dawkins discussed Jaynes's theory in his recent book The God Delusion. In his chapter on the roots of religion, Dawkins writes: "It is one of those books that is either complete rubbish or a work of consummate genius, nothing in between! Probably the former, but I'm hedging my bets." Others considered Jaynes's hypothesis worthy and offer conditional support, arguing the notion deserves further study.
In a 1987 letter to the American Journal of Psychiatry, Dr. H. Steven Moffic questioned why Jaynes's theory was left out of a discussion on auditory hallucinations by Drs. Assad and Shapiro. In response, Drs. Assad and Shapiro wrote, "…Jaynes' hypothesis makes for interesting reading and stimulates much thought in the receptive reader. It does not, however, adequately explain one of the central mysteries of madness: hallucination."
Drs. Asaad and Shapiro's comment that there is no evidence for involvement of the right temporal lobe in auditory hallucination was incorrect even at that time. A number of more recent studies provide additional evidence to right hemisphere involvement in auditory hallucinations. Recent neuroimaging studies provide new evidence for Jaynes's neurological model, i.e. auditory hallucinations arising in the right temporal-parietal lobe and being transmitted to the left temporal-parietal lobe. This was pointed out by Dr. Robert Olin in Lancet and Dr. Leo Sher in the Journal of Psychiatry and Neuroscience, and further discussed in the book Reflections on the Dawn of Consciousness.
The philosopher Daniel Dennett suggested that Jaynes may have been wrong about some of his supporting arguments, especially the importance he attached to hallucinations, but that these things are not essential to his main thesis. He also wrote that:
If we are going to use this top-down approach, we are going to have to be bold. We are going to have to be speculative, but there is good and bad speculation, and this is not an unparalleled activity in science. […] Those scientists who have no taste for this sort of speculative enterprise will just have to stay in the trenches and do without it, while the rest of us risk embarrassing mistakes and have a lot of fun. --Daniel Dennett
Gregory Cochran, a physicist and adjunct professor of anthropology at the University of Utah, wrote: "Genes affecting personality, reproductive strategies, cognition, are all able to change significantly over few-millennia time scales if the environment favors such change — and this includes the new environments we have made for ourselves, things like new ways of making a living and new social structures. ... There is evidence that such change has occurred. ... On first reading, Breakdown seemed one of the craziest books ever written, but Jaynes may have been on to something." Author and historian of science Morris Berman writes, "[Jaynes's] description of this new consciousness is one of the best I have come across." Danish science writer Tor Nørretranders discusses Jaynes's theory favorably in his book The User Illusion: Cutting Consciousness Down to Size.
Evidence taken to contradict Jaynes's proposed date of the transition from bicameralism is the Gilgamesh Epic: although the story of Gilgamesh was recorded centuries before the Old Testament, and though its setting is contemporaneous or earlier than the Old Testament stories, the Gilgamesh story describes such features as introspection. Jaynes himself, noting that the most complete version of the Gilgamesh epic dates to post-bicameral times (7th century BC), dismisses these instances of introspection as the result of rewriting and expansion by later conscious scribes, and points to differences between the more recent version of Gilgamesh and surviving fragments of earlier versions. ("The most interesting comparison is in Tablet X." - detailed in The Origin of Consciousness, 1982 edition, p. 252f.) Others, such as science fiction author Neal Stephenson in Snow Crash, have since conjectured that heroic epics and myths may be rooted in isolated individuals who became self-aware early and could accordingly outmatch and manipulate their fellows.
Brian McVeigh maintains that many of the most frequent criticisms of Jaynes' theory are either incorrect or reflect serious misunderstandings of Jaynes' theory, especially Jaynes' more precise definition of consciousness. Jaynes defines consciousness—in the tradition of Locke and Descartes—as "that which is introspectable." Jaynes draws a sharp distinction between consciousness ("introspectable mind-space") and other mental processes such as cognition, learning, and sense and perception—which occur in all animals. He argues that this distinction is frequently not recognized by those offering critiques of Jaynes' theory.
Similar ideas 
Neuroscientist Michael Persinger has studied the role of the right temporal lobe in the feeling of a sensed presence and god beliefs by stimultation with a so-called God helmet. The neuroscientist V.S. Ramachandran discusses cases of hyperreligiosity in patients with temporal lobe epilepsy. Other theorists have also made the claim that consciousness is a social construction, including Lev Vygotsky, Rom Harré, and George Herbert Mead. Cognitive psychologist David R. Olson has written on the impact of reading and writing to cognition and the mind. Lloyd deMause and the psychohistorians have advanced a model that aims to understand the ubiquity of the schizotypal personality in the Old World. The main difference between psychohistorians and Julian Jaynes is that psychohistorians focus on childrearing modes as the main cause of the schizoid personality.
In his book The Master and His Emissary, psychiatrist Iain McGilchrist reviews scientific research into the role of the brain's hemispheres, and cultural evidence, and he proposes that since the time of Plato the left hemisphere of the brain (the "emissary" in the title) has increasingly taken over from the right hemisphere (the "master"), to our detriment. McGilchrist, while accepting Jayne's intention, felt that Jayne's hypothesis was "the precise inverse of what happened" and that rather than a shift from bicameralism there evolved a separation of the hemispheres.
The Origin of Consciousness was financially successful, and has been reprinted several times. The book was originally published in 1976 (ISBN 0-395-20729-0) and was nominated for the National Book Award in 1978. It has since been reissued (ISBN 0-618-05707-2). A new edition, with an afterword that addressed some criticisms and restated the main themes, was published in the US in 1990. This version was published in the UK by Penguin Books in 1993 (ISBN 0-14-017491-5). It has been translated into Italian, Spanish, German, French, and Persian.
See also 
- Behavioral modernity
- Dual brain theory
- FOXP2, a gene that is implicated in the development of language skills.
- Lateralization of brain function
- Mythopoeic thought
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- Jaynes, Julian. (1976) The Origin of Consciousness in the Breakdown of the Bicameral Mind. Pg. 221
- Zechariah, 13: 2-3
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- Keen, Sam, "Julian Jaynes: Portrait of the Psychologist as a Maverick Theorizer," Psychology Today, November 1977, vol 11, pp. 66-7
- Keen, Sam, "The Lost Voices of the Gods (Interview with Julian Jaynes)", Psychology Today, November 1977, vol 11, pp 58-60
- Moffic, H. Steven (May 1987). "What About the Bicameral Mind?". American Journal of Psychiatry 144 (5).
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- Olin, Robert (1999). "Auditory Hallucinations and the Bicameral Mind". Lancet 354 (9173): 166. doi:10.1016/S0140-6736(05)75304-6. PMID 10408523.
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- Kuijsten, Marcel (2007). Reflections on the Dawn of Consciousness: Julian Jaynes's Bicameral Mind Theory Revisited. Julian Jaynes Society. pp. s. 116–120. ISBN 0-9790744-0-1.
- Dennett, Daniel (1986). "Julian Jaynes's Software Archeology". Canadian Psychology 27 (2).
- Daniel Dennett (1998) "Julian Jaynes’s Software Archeology." In: Brainchildren: Essays on Designing Minds.
- Edge Foundation (2006). "What Is Your Dangerous Idea?" http://www.edge.org/q2006/q06_4.html
- Berman, Morris (2000). Wandering God: A Study in Nomadic Spirituality. ISBN 0-7914-4442-2.
- Nørretranders, Tor (1991). User Illusion: Cutting Consciousness Down to Size. ISBN 0-7139-9182-8.
- McVeigh, Brian (2007). "Elephants in the Psychology Department: Overcoming Intellectual Barriers to Understanding Julian Jaynes's Theory". Julian Jaynes Society.
- Persinger, Michael (1987). Neuropsychological Bases of God Beliefs. Praeger. ISBN 0-275-92648-6.
- Ramachandran, V.S. (1999). Phantoms in the Brain: Probing the Mysteries of the Human Mind. Harper Perennial. ISBN 0-688-17217-2.
- Vygotsky, Lev (1962). Thought and Language. MIT Press. ISBN 0-262-22029-6.
- Harré, Rom (1984). Personal Being. Harvard University Press. ISBN 0-674-66313-6.
- Mead, George H. (1934). Mind, Self, and Society. Chicago University Press. ISBN 0-226-51667-9.
- Olson, David R. (1994). The World on Paper: The Conceptual and Cognitive Implications of Writing and Reading. Cambridge University Press. ISBN 0-521-44311-3.
- deMause, Lloyd (2002). The Emotional Life of Nations. Other Press. ISBN 1-892746-98-0. Archived from the original on 2002-10-06.
- McGilchrist, Iain (2009). The Master and his Emissary. Yale University Press. p. 262. "I believe he [Jayne] got one important aspect of the story back to front. His contention that the phenomena he describes came about because of a breakdown of the 'bicameral mind' - so that the two hemispheres, previously separate, now merged - is the precise inverse of what happened."
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