Neuroscientists have long known that most of what goes on in the brain is pre-conscious. Compelling evidence of this fact can be found in the work of scientists who have calculated the bandwidth of human consciousness. Researchers at the university of Pennsylvania, for example, have found that human retina transmits to the brain approximately 10 million bits of information per second, roughly the capacity of an ethernet connection; and Manfred Zimmermann, a german psyschologist, has calculated that our senses record an addtional one million bits per second. that gives our senses a total bandwidth of 11 million bits per second. Yet of this massive flow of information no more than about 40 bits per second actually reaches consciousness. We are, in other words, conscious of only a trivial slice of all the information coming into the brain for processing.
From John Coates amazing book, The Hour Between Dog & Wolf;