THE ANATOMY OF CONSCIOUSNESS • 29information—such as differentiated sounds, or visual stimuli, or recog
nizable nuances of emotion or thought—at any one time, and that the
shortest time it takes to discriminate between one set of bits and another
is about ‘/is of a second. By using these figures one concludes that it
is possible to process at most 126 bits of information per second, or
7,560 per minute, or almost half a million per hour. Over a lifetime of
seventy years, and counting sixteen hours of waking time each day, this
amounts to about 185 billion bits of information. It is out of this total
that everything in our life must come—every thought, memory, feeling,
or action. It seems like a huge amount, but in reality it does not go that
far.
The limitation of consciousness is demonstrated by the fact that
to understand what another person is saying we must process 40 bits of
information each second. If we assume the upper limit of our capacity
to be 126 bits per second, it follows that to understand what three
people are saying simultaneously is theoretically possible, but only by
managing to keep out of consciousness every other thought or sensation.
We couldn’t, for instance, be aware of the speakers’ expressions, nor
could we wonder about why they are saying what they are saying, or
notice what they are wearing.
Of course, these figures are only suggestive at this point in our
knowledge of the way the mind works. It could be argued justifiably that
they either underestimate or overestimate the capacity of the mind to
process information. The optimists claim that through the course of
evolution the nervous system has become adept at “chunking” bits of
information so that processing capacity is constantly expanded. Simple
functions like adding a column of numbers or driving a car grow to be
automated, leaving the mind free to deal with more data. We also learn
how to compress and streamline information through symbolic means—
language, math, abstract concepts, and stylized narratives. Each biblical
parable, for instance, tries to encode the hard-won experience of many
individuals over unknown eons of time. Consciousness, the optimists
argue, is an “open system”; in effect, it is infinitely expandable, and
there is no need to take its limitations into account.
But the ability to compress stimuli does not help as much as one
might expect. The requirements of life still dictate that we spend about
8 percent of waking time eating, and almost the same amount taking
care of personal bodily needs such as washing, dressing, shaving, and
going to the bathroom. These two activities alone take up 15 percent
of consciousness, and while engaged in them we can’t do much else that
requires serious concentration. But even when there is nothing else