Roughly the same error as the above is made by Barfield in his review:
"The psycho-history of mankind, he says, can be understood only as an age-long progress, or transition, from the dominance of the right hemisphere, through a “bicameral mind” period when the
two hemispheres were both about equally effective, into the dominance of the left hemisphere, which largely prevails today and which may end either in the total atrophy of the right hemisphere or, better, in the reestablishment of a proper balance between them."
Jaynes was not saying the hemispheres were "equally effective," but instead, suggested right hemispheric dominance in BC-times (for anything important that is--not habitual tasks, of course). Cerebral asymmetry already existed--the conscious mind is just a different arrangement of that asymmetry (LH-dominant).
Aside from such mistakes, it is also rather annoying that Jaynes is criticized by one party for denying biology any role in consciousness, another party for including all of this nonsense about the double brain, etc--that is, everyone can find something to criticize, so long as they pretend that other parts of his argument don't exist. For Koch, he says too little about the brain; for Barfield, too much. Can't win! (Barfield's review is pretty good though IMO)
"By giving consciousness a cultural origin, says Christof Koch, chief scientific officer at the Allen Institute for Brain Science, 'Jaynes disavows consciousness as a biological phenomenon.'"
http://nautil.us/issue/24/error/conscio ... d-speaking"A reviewer may be pardoned for raising the perhaps irritating question: Then why all this stress on the not-very-relevant physical brain? If the division of labor between its two hemispheres in any particular epoch is likely to have been organized by cultural and aesthetic activity, and is in any case only inferable from cultural and aesthetic phenomena, to what exactly is it the master key?"
http://www.owenbarfield.org/bicameral-mind/