The Enchanting Subject Of Consciousness (Or Is It A Black Hole?)
Review of Enchanted Looms: Conscious Networks In Brains and Computers By Rodney Cotterill
John G. Taylor
Centre for Neural Networks
Department of Mathematics
King's College, Strand
London, WC2R 2LS
U.K.
john.g.taylor@kcl.ac.uk
Copyright (c) John Taylor 2000
PSYCHE, 6(2), February 2000
Previously Held: http://psyche.cs.monash.edu.au/v6/psyche-6-02-taylor.html
KEYWORDS: Consciousness, neural networks, binding, attention, qualia unconsious processing, filling in.
REVIEW OF: Rodney Cotterill (1998) Enchanted Looms: Conscious Networks in Brains and Computers. Cambridge, UK: Cambridge University Press, 400 pp. ISBN: 0 521 62435 5
(hardback) AUS$ 44.95
The subject of consciousness is proving to be almost like a black hole
to those who draw close to it. Once seduced inside the event horizon,
they appear lost to normal scientific activity but follow a trajectory
towards an explanation of the phenomenon which others, standing well
away from the fateful edge, shout out to them is impossible to follow
scientifically or is of little interest to those in the scientific
mainstream. Those already lost to the black hole hear the cries of their
companions but cannot escape the fatal attraction exerted on them. And
as more and more fall into the black hole it expands, so swallowing more
and more into its ever roomier interior. Will information ever get out
about what the intrepid explorers have discovered? Or will there just be
a gradual separation into those who have disappeared and those who
resolutely turn their eyes from the glorious sight of infalling
colleagues.
The above is a bit of exaggeration, I grant, but is along the lines of
comments I myself have received about my own interest in consciousness,
both from colleagues and my nearest and dearest. Rodney Cotterill has
also fallen into the black hole of consciousness, but he has shown by
his excellent book that information can be sent back from inside the
event horizon. It may be just part of the radiation of heat from the
surface (the so-called "Hawking radiation"), but it contains some
important indications of the nature of the interior. It is also
beautifully written. Indeed, the dedication at the beginning -- "for all
who care for the mentally infirm" -- is apposite, indicating that the
book has been written from the heart as well as the head.
Cotterill starts with a gentle introduction to the nature of and puzzles
about conscious experience, including a very effective picture of the
author drawn by portrait-drawing robot in Japan (in actuality by a
line-extraction algorithm), and moves on to a description at a simple
level of the anatomy and physiology of the brain. A good description of
brain imaging and the difference between top-down and bottom-up
processing then follows. A chapter on the living neuron and brain-type
neural networks then leads to neural network learning rules and their
relation to some of the learning processes in the brain, including
associative memory nets, topographic maps and feedforward nets learning
by the delta rule. The complexity of visual processing and the
marvellously crystalline structure of the cerebellum are then described,
including muscular and emotional control systems in the brain. Synchrony
and the binding problem and attentional processing are then clearly
considered, moving to eye movements and visual processing as a set of
associated actions, and the involvement of working memory in
higher-level processing. The results of Libet on the timing of
consciousness in relation to spontaneous movements are briefly
discussed, before a return to consciousness at page 293, in which there
is emphasis on unconscious processing as prior to the emergence of
consciousness.
We have now come to the longest (83 pages) and most important chapter of
the book, entitled "Midwives of Reflection". It is in this chapter that
the main intellectual meat of the book resides, the real message coming
out of the "black hole" of consciousness research. It commences with a
discussion of the problems associated with the definition of
consciousness, and the beginnings of the deeper analysis of human
conscious experience by a discussion of the phenomenon of "filling in",
the gap in visual experience associated with the blind spot. Cotterill
shows some excellent "hands-on" examples of this, and justifies the
presence of some form of inner experience -- the controversial "qualia"
-- which is missing in a blind person (so countering the argument of
Dennett that qualia do not exist, since he claimed that there is no
filling in for the blind spot, in contradiction to actuality). This
leads to a vivid description of other sensory illusions, such as the
cutaneous rabbit, and so to the body matrix of Melzack. It is the latter
which is suggested as being involved in the process of filling in; it is
an automatic process at an unconscious level. A discussion of Searle's
features of unity of conscious experience, intentionality and focus
versus periphery is then given, and Sommerhoff's Integrated Global
Representation mentioned.
However, this still does not home in on consciousness in any precise
way, as Cotterill admits. After some further remarks on top-down versus
bottom-up, consciousness begins to emerge in the section "The theatre
that never closed" as "a mechanism that enables us to relate to our
personal space," which needs considerable unpacking, some of which is
begun in that section. He claims that the key to consciousness is time:
"And I believe that the key factor is time. If the organism is to have
the ability of responding to the temporal texture of its environment, on
the time scale inherent in that texture, it will have to be able to
retain a temporary record that spans a sufficient amount of that
texture." An appeal to action-based perception and the active
acquisition of information finally leads to a description of the
suggested "core circuitry of consciousness". This involves a set of
recurrent loops joining the posterior lobes to the frontal lobe of the
brain. This is supported by some brain imaging results and developed in
more detail in the following subsections. To get to the nub, qualia are
proposed to arise from motor action and internal re-afference, suggested
as arising from intrafusal fibre activity developed from independent
gamma neurons; thus we arrive at "the idea that qualia are inextricably
related to the body's musculature...", for which some evidence is
presented. Further discussion ensues on volition, sleep, language,
intelligence (in humans and other primates), concluding with the
impressively entitled section "Consciousness will be seen in computers".
I have a number of cavils about small points, such as that the scan-path
approach (p. 277) to visual processing has now been discarded by
psychologists; only 250 milliseconds (p. 293) are needed for
consciousness to be aroused in a replication of Libet's experiment on
consciousness of spontaneous motor acts (Keller and Heckhausen,
1990). Moreover, the latter experimental duplication leads to a very
different view of the way that consciousness is implicated: "...the time
of feeling an urge to move necessarily coincides with the change of
control from a lateral unconscious to a medial conscious process." In
the process, it is attention to naturally occurring unconscious motor
acts, asked for by the experimenter, which causes the acts to be driven
into consciousness. There is no problem about "free will" from this
point of view.
I have a deeper point to make about the nature of consciousness being
presented in the book. At the end of the book Cotterill states "What,
then, is my prescription for simulating consciousness in a computer?
That is one of the things this entire book has been leading up to,
because the only reliable way to achieve this goal would be to emulate
the anatomy and physiology of the only structure we can be sure is
conscious: the human brain." As he then admits, this is a bit of a
cop-out since it will be a long time off before such a complex
simulation will be done. However it is not clear to me that such a
simulation would do the trick, since we know that it is being replicated
in wet-ware every second by billions of examples here on earth. It would
still leave unprobed the principles on which the emergence of conscious
experience depends. It is that which this book was about. Why did
Cotterilll not follow up the issue of time that he emphasised for
consciousness, as I noted earlier? There are numerous approaches using
working memory modules as basic to this emergence (as discussed, for
example, in Taylor, 1999). These systems handle time in a flexible and
powerful manner and are closely related to attentional brain centres, as
modern brain imaging experiments have now shown. The basing of
consciousness on gamma afferent feedback is also dangerous, in the light
of results on deafferented patients who have difficulties of movement
but not apparently of consciousness (Cole and Paillard, 1995).
However, these comments are part of the controversial subject that is the study of consciousness. In all, this is a beautifully written book, and one of value to anyone wandering near the black hole of consciousness. It is one of an increasing number of messages now coming out from the event horizon, suggesting that the hole may not be so black as it seems.
References
Cole, J. & Paillard, J. (1995). Living without touch and peripheral
information about the body position and movement: Studies with
deafferented subjects. In J.L. Bermudez, A. Marcel & N. Eilan
(Eds.) The Body and The Self* (pp. 245-266). Cambridge, MA: MIT
Press.
Keller, J. & Heckhausen, H. (1990). Readiness potentials preceding
spontaneous motor acts: voluntary vs. involuntary
control. Electroencephalography and Clinical Neuropsycholgy, 76,*
351-361.
Taylor, J.G. (1999). The race for consciousness. Cambridge, MA: MIT
Press.
