Archive for January, 2005

Johnjoe McFaddenBitbucket Susan Pockett isn’t the only person who thinks consciousness is basically an electromagnetic field. Johnjoe McFadden put forward a similar theory back in 2000 and his version has some advantages. There is a short account of the theory on his own website at the University of Surrey, with the two papers which flesh it out more fully. In his view, the endogenous electromagnetic (em) field produced by the human brain contains the same information as the neurons, but in a form which is analogue, integrated and distributed; all characteristics which seem to be shared by consciousness and not by the digital, discrete activity of the neurons themselves. His version of the theory steers well clear of epiphenomenalism and all its problems: the em field arises from neuronal activity in a normal way and has straightforward causal effects on the firing of neurons in its turn.

He concedes that the very small charges involved may mean that quantum effects are relevant; but quantum mechanics plays no special part in the theory and he does not rely on strange quantum effects to explain the strange properties of consciousness. 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.
BlandulaThat’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.
Bitbucket 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 artificial 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.
Blandula 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.
Bitbucket 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.
BlandulaThe 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.

Bitbucket First, it’s obvious that a degree of complexity 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, they undoubtedly 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.
Blandula>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?

BitbucketYes, of course. The distinction is a practical one which could no doubt be sharpened up theoretically: the basic point is clearly that we’re 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.

Blandula I don’t see that. Part of the binding problem is how processes which run at different speeds are co-ordinated: how does an instant field cope with that? And it seems to me that a single field would bind things together too much: if that’s where our view of reality comes from it would all be hopelessly melted together in an incoherent buzz. It is of the essence that the right things get bound together in the right way, not just instantly smudged together.
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.

Bitbucket 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.

Blandula The trouble with those ephaptic effects is that, as I understand it, they are mainly associated with disorders, like tinnitus. They’re like the sort of interference you would sometimes get between old-fashioned phone wires because of induction; unwanted signals in a system which was designed to work without them. After all, neurons go to great lengths to connect up with each other, often at great distances; surely direct effects from an em field are just going to be unhelpful noise.
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.

Bitbucket 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.