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30 January 2005 |
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It does seem, however, that his theory can clarify a lot of different problems. The distinction between conscious and unconscious action, for example, is simply a matter of whether the em field was, or was not, playing a decisive role at the time. As we drive along the road, our over-learned responses produce robust patterns of firing in the neurons which require no intervention from the em field; but if we hit a novel situation our neuronal response becomes confused and less co-ordinated, and the subtle influence of the em field takes over - we begin to think about what we are doing again. |
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 That's all very well - but we
don't stop thinking altogether while we're driving. If our mind wanders,
we start thinking about something else. If McFadden is right, these other
thoughts must be coming from neuronal activity too, mustn't they? So he
thinks that in that case the electromagnetic field will be most
influenced, not by the strongest patterns of firing, but by weaker ones?
That doesn't make much sense. If his theory were right, it wouldn't be
that our mind wanders - we'd suddenly find that our actions had gone
terrifyingly out of conscious control every time a habitual pattern of
behaviour kicked in.
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 No, no. How could we be terrified by something which,
by definition, we have stopped paying attention to? Besides, the contents
of consciousness are not decided merely by the largest electrical
influence - I'll explain that in a moment. The theory also offers a
convincing explanation of qualia. It would be perfectly possible for our
brains to run unconsciously through pure neuronal computation, taking
account of sensory inputs and modifying behaviour accordingly -
but it is the extra buzz of em activity which gives them their phenomenal
qualities, engaging them in the process of consciousness. This view has
the advantage of setting qualia apart from the routine causality of
mental processes without rendering them irrelevant. McFadden thinks fading
and absent qualia are perfectly possible; but at the same time a person or
robot without qualia would be readily distinguishable from a fully
conscious person. McFadden doesn't think, incidentally, that artifical
consciousness is impossible, if the machine were constructed in the right
way. There are fascinating results here from Sussex University. A neural
network was trained to distinguish two tones: once trained it emerged
that some of the cells which were essential to performing the task
were not actually connected to the rest! The only explanation is
that they were contributing to the performance of the network through some
field effect - very much as the em field hypothetically would do. The
implication is that this network had a dim, restricted form of phenomenal
experience. | ||
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| I
simply don't see why we should assume that an electromagnetic 'buzz' has
anything more to do with qualia and actual experiences than the firing of
neurons (or any other physical process). The problem is that physical
processes and real experiences are as different as chalk and cheese, and
substituting one physical process for another makes no difference
whatever. | ||
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| If you take that line, you're simply making the
problem unanswerable by definition. But anyway, McFadden's theory also
offers an obvious solution to the issue of free will. The problem with
free actions is that they seem to come out of nowhere; well, the truth is
that come out of the em field. They really are exceptions to the
underlying neuronal causal process, but there's nothing spooky or magic
about them: they are perfectly normal results of normal physical
processes. | ||
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| The theory
seems incomplete to me. After all, the brain (and the rest of the body) is
full of activity which generates electromagnetic fields. Why should only
some of them, on this reading, be conscious? For that matter, why aren't
ambient electromagnetic fields, like that of the Earth itself, conscious?
Why don't television broadcasts have minds of their own, and given the
strength of them, why don't they over-ride our conscious thoughts? At
least Susan Pockett acknowledges that only certain kinds of patterns of
activity can be conscious. | ||
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| First, it's obvious that a degree of somplexity is necessary:
no one supposes a simple electromagnetic field is automatically conscious.
Second, the brain is actually rather well insulated from outside fields.
Where magnetic fields are strong enough and targeted in the right place,
theyundoubtedly do disrupt mental activity. Although there is a difference
here between Pockett and McFadden, he accepts that not all field
effects arising from the brain are the same. He specifies that only
those which eventually influence motor neurons are to be regarded as
conscious. | ||
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| Why only
those? it seems a very arbitrary distinction. And at the time some field
event takes place, you can't tell for sure whether it will set off a chain
of events that impinges on motor neurons, can you? But it must either be
conscious or not at the time it happens, surely? | ||
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| Yes, of course. The distinction is a practical one which
could no doubt be sharpened up theoretically: the basic point is clearly
that we'r talking about reportable processes in some sense. But we still
haven't touched on possibly the strongest advantage of the theory, namely
that it also deals with the binding problem. It has always been a mystery
how the different bits of data from different senses get bound together
into a coherent, consistent account of reality: but if there is an
overarching em field which picks up neuronal influences from all the
senses and transmits the combined result instantly over the brain, the
solution is clear. | ||
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What really puts me off the theory, though, is that it seems like another blow in favour of electricity. We've always suffered from treating the brain as if it were made of copper wire, when it's perfect clear that subtle chemical effects are absolutely crucial. In fact, I'd say one of our big problems here is that we draw a major distinction between physics and chemistry which Nature simply doesn't recognise. | ||
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| There's an element of truth in that, but I think
McFadden's theory is a corrective to the 'copper-wire' view, not a
reinforcement of it. He points out that these effects exist - ephaptic
coupling of nerve activity through electromagnetic fields is an
established fact - and surely they need to be considered. | ||
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The bottom line here is that McFadden (and Pockett) want electromagnetism to do what the spirit does in traditional accounts, but it just isn't up to the job. | ||
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| I see it as a strength of the theory that it sits well
with intuitive and traditional ideas about the way the mind works, while
requiring nothing but ordinary mainstream science to sustain it. One of
its virtues is that it is amenable to experimental testing, and I have no
doubt that over time evidence will accumulate. What I'd really like to see
is an AI project in parallel, seeing whether there aren't practical
advantages to the kind of set-up McFadden describes. Unfortunately I don't
think this is happening at the moment. | ||
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