Superior Index Go to the next: Chapter 9
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Like any theory worth its salt, the one being put forward here has been the subject of a number of challenges, most of which are listed below. I would like to emphasize that none of these objections is a straw man. All have actually been put forward in opposition to the theory - most of them by anonymous journal referees, but some by friends or by people who at least were willing to sign their names to their misgivings. These objections are as follows:
Objection 1: If consciousness is a pattern in the electromagnetic field, one would expect that electric fields like those generated by power cables or domestic mains voltages, or magnetic fields such as those generated by MRI (magnetic resonance imaging) machines should directly affect consciousness. They demonstrably do not. Therefore the theory must be wrong.
It is certainly true that no subjectively discernable changes in consciousness are produced by the proximity of a wall socket or an overhead power transmission line. However it is not true that such changes would be expected. The rate of radiation of energy by oscillations of any field is proportional to the fourth power of the frequency of the oscillations, so at mains voltages of 230 or 110 volts the amount of radiation generated by oscillations at 50 or 60 Hz is tiny. While mains voltage can certainly introduce artefacts into the recording of EEGs, by inducing currents in the wires connecting the recording electrodes to the amplifiers, it simply does not produce strong enough radiation to alter the intricate spatial electromagnetic configurations proposed to be consciousness at their generation sites in the brain. If major external electric currents are passed directly through the brain, as in electroconvulsive therapy, there are genuine disruptions of the electric fields within the brain and there are also major disruptions in consciousness. (This can only be regarded as supportive and not conclusive evidence for the present hypothesis however, since electroconvulsive therapy also changes patterns of neural firing and various other physiological parameters). But it is highly unlikely that radiation from domestic power lines could induce any disruption of the electric field patterns in the brain.
On the other hand, the magnets in MRI machines do produce huge magnetic fields, which should in principle be large enough to affect intracerebral electromagnetic configurations. It is also true that the only changes in consciousness that are occasionally experienced in MRI machines are some visual scintillations, which are generally thought to be caused by firing of neurons induced by the machine-generated electromagnetic fluctuations. As with radiated 50 Hz electric fields, the external magnetic fields generated by an MRI machine certainly do affect the recording of EEG waveforms, by inducing currents in the recording hardware, but the question still is whether there could be any effective coupling between the imposed magnetic fields and the kinds of intricate spatial electromagnetic configurations proposed as being consciousness. In other words, do the magnetic fields in an MRI machine materially affect the brain-generated spatiotemporal configurations we are talking about at their source?
This is a question probably best attacked empirically. Recent advances in technology have allowed the recording of EEGs inside MRI machines and the answer seems to be that once the recording artefacts are dealt with, the magnetic field in MRI machines does not significantly affect the EEG (Allen, Polizzi, Krakow, Fish, & Lemieux, 1998 [13]; Jenkins, et al., 1996 [131]; Muri, et al., 1998 [202]). Of course more such studies will be necessary when the precise spatiotemporal patterns that covary with particular sensory experiences have been identified. In fact this is a very good potential source of disconfirming data, but the indications so far are good for the theory.
Objection 2: If consciousness is an oscillation in the electromagnetic field then it should be able to be radiated by the brain and therefore telepathy should at the very least be more common than it is (assuming that one believes it ever does occur). Telepathy is actually rare or non-existent - certainly not an everyday phenomenon. Therefore the theory must be wrong.
The answer to Objection 2 is closely related to the answer to Objection 1. It concerns the known physics of electromagnetic radiation. The frequency of the major electromagnetic oscillations generated by the brain is in the range from 1 to about 100 Hz, with most of the power below around 45 Hz. The wavelength of 40 Hz electromagnetic oscillations can be calculated (by dividing the speed of light by the frequency of the oscillations) at approximately 8,000 km. The optimal length of antenna for picking up a radio signal is about one wavelength, so the optimal length of antenna for picking up 40 Hz radiation would be 8,000 km (which is somewhat larger than the size of a human brain). As mentioned above, the rate of radiation of energy by oscillations of any field is proportional to the fourth power of the frequency of the oscillations. Therefore the energy radiated at 40 Hz by a power source like the brain would be so small that either an extremely sensitive detector or an antenna approximately 8,000 km long would be needed, even to detect a generalised broadcast signal. To retrieve any specific information, the signal would probably need to be carried by oscillations with a wavelength similar to the size of the brain, which translates to microwave frequencies. Thus on the present hypothesis telepathy would not, in fact, be expected to be a common event.
Interestingly however, there is some evidence that external modulation of the brain's electromagnetic field can modulate conscious experience. For example:
These findings both support the present hypothesis and leave open the possibility that if the present hypothesis is correct, telepathy might be expected occasionally to occur. This is not the place to attempt a critical review of the extensive scientific literature on telepathy, but it is interesting in an anecdotal way to note that an experience of telepathic communication with his sister in a moment of crisis is reported to have been the impetus that led Hans Berger to initiate his original work on the human EEG. It is also interesting that the speculations above suggest the idea that the signals we are looking for in brain-generated electromagnetic activity might actually not be in the ELF (extremely low frequency) range where everyone is presently looking, but could turn out to be closer to the microwave frequency range - which is of course always filtered out in present-day electrophysiological recordings.
Objection 3: If, as proposed, the consciousness of an individual is the totality of the conscious configurations of the electromagnetic field that is associated with that individual's brain, then cutting the corpus callosum should have no noticeable effects on consciousness, since the field generated by one half of the brain is still contiguous with the field generated by the other half. But this operation apparently produces two individual consciousnesses associated with the one brain. Therefore the theory must be wrong.
This objection goes to a theory that purports to explain self consciousness, which the present theory does not. As pointed out in Chapter 1, the present theory is, at least at this stage, confined to simple consciousness. However the objection is a cogent one and deserves to be addressed.
Again, empirical findings must take precedence over predictions. A little delving into the voluminous empirical literature on split brains quickly reveals that, far from having a "split personality", split brain patients are actually remarkable mainly for the fact that it is very difficult to detect any changes at all in their consciousness. In fact early investigators were led to the exasperated and facetious conclusion that the purpose of the corpus callosum "must be mainly mechanical ... to keep the hemispheres from sagging" (Lashley quoted by Kandel et al (Kandel, Schwartz, & Jessell, 1995 [140])). It was not until Roger Sperry performed a series of clever experiments involving presentation of sensory input to only one half of the brain (a situation which virtually never occurs in everyday life) that the separation of right brain from left brain in commissurotomised patients could be detected behaviorally at all (Sperry, 1982 [265]; Sperry, 1984 [266]; Sperry, 1966 [267]; Sperry, 1968 [268]). Recent work in what then became a huge research field arrives at the conclusion that, in the case of vision for example, interhemispheric transfer of information is not entirely absent in commissurotomised subjects. There appear to be two systems, one of which can be split and the other which can not (Corballis, 1994 [57]; Corballis, 1995 [58]). There is no universally accepted explanation for the fact that part of the system of visual experience can not be split by cutting the corpus callosum. One possibility is that this system is subserved by the conscious field.
Objection 4: This is not a new theory - it was the secret hope of early EEG workers and it was put forward by Popper. However it was tested and disproved by Kohler, Lashley and Sperry in the 1940s and 50s. The theory has already been shown to be wrong.
As mentioned above, it is quite likely that Hans Berger did secretly hope to discover the secrets of consciousness by studying the EEG. However, being a good Teutonic scientist, he was careful never to state this in print - and none of the other early EEG workers made any such statements either, at least to my knowledge. The present theory was certainly not put forward in Karl Popper's published writings. Again to my knowledge, even Wolfgang Kohler never actually proposed in so many words that consciousness was identical with certain configurations in the electromagnetic field, although his Field Theory certainly skirts around the issue. The experiments by Lashley and Sperry which are often misconstrued as being adequate tests of either Kohler's theory or the present one are discussed in Chapter 7. In my view they do not disprove either hypothesis.
Objection 5: You haven't shown that electromagnetic fields can actually process information, as consciousness can. Neurons can do information processing, either by acting as switches or by acting as analogue systems, but there is no evidence that electromagnetic fields can perform that kind of computing. But consciousness does do information processing. Therefore the theory can't be accepted at this stage
This objection can be approached from two angles:
This is not entirely a comfortable response to the objection as stated however. The reader fresh from Chapter 7 may notice a certain ambivalence here about whether consciousness per se does or does not have any causal effects (which could perhaps be equated with information processing, although it is not entirely clear just what the latter necessarily entails). Therefore it comes as some relief to note that
The information processing possible using this kind of volume conduction mechanism is almost certainly blunter (less accurate and in some ways slower) than that possible using the precise digital properties of neuron-to-neuron transmission - but then so is the information processing that is postulated to occur in the conscious "global workspace" which is proposed by the leading process theory of consciousness (Baars, 1988 [16]).
Objection 6: This theory has no obvious advantages over the Neural Identity theory (which basically says that brain events per se are identical with consciousness). Therefore the theory can't be accepted at this stage
This objection is basically a statement that the psychoneural identity theory currently has possession of the minds of nine tenths of the biologists who think about these matters and that possession is nine tenths of the law. Against this it can be argued that even if the electromagnetic field theory did have no advantages over the neural identity theory, it is not necessarily the case that whatever theory appeared on the scene first is necessarily the right one.
However, it is true that most biologists at the end of the twentieth century do uncritically accept the psychoneural identity theory and therefore feel that even the consideration of any other theory is an unnecessary waste of time. So a discussion of the shortcomings of the psychoneural identity theory and a comparison of these with the advantages of the electromagnetic field theory is probably inevitable.
The first problem we encounter in attempting to discuss the psychoneural identity theory, however, is the lack of a clear statement of that theory. The generally accepted meaning of psychoneural identity is that consciousness is identical with brain events. But with what feature of brain events is it proposed that consciousness is identical? Obviously it is not simply the physical anatomy of the brain which is identical with consciousness, because in that case the brains of newly dead persons (or sleeping or anesthetised persons) would still be conscious. Perhaps it is the case that neural tissue contains some undiscovered Factor X - a chemical perhaps - which bestows the property of consciousness and disappears on death (or during sleep or anesthesia). In that case only some sorts of neural tissue must carry this factor and then only intermittently, because most of what goes on in the brain is not conscious for most of the time. This latter fact also poses a problem for the idea that the firing of action potentials per se is identical with consciousness. The peripheral motor nerves in the big toe fire action potentials and these are (almost) identical with the action potentials in the visual cortex, in terms of the movement of ions through membrane channels that underlies them. Is the big toe conscious? Most neurobiologists would say that it is not. But is the visual cortex conscious? Probably. Sometimes. So what's the difference? Well, if action potentials themselves are uniform in kind, perhaps there are "awareness neurons" which have special ways of firing action potentials. Perhaps particular kinds of bursts of action potential firing constitute consciousness, for example. This doesn't seem very likely and there is no evidence whatsoever connecting the idea to the realities of consciousness as measured in the laboratory. We're definitely struggling here.
Finally, we are forced to the conclusion that the only viable formulation of the psychoneural identity theory is that of the emergent-property theorist. Roger Sperry (Sperry, 1969 [269]) argues that consciousness is an emergent property of matter organized as nervous tissue. By this he means that consciousness is something "different from and more than" the sum of its parts, which emerges out of the complex spatiotemporal interaction of billions of neural elements. One more step and this would be the electromagnetic field theory of consciousness. But Sperry did not take that step.
So the ultimate version of the psychoneural identity theory turns out to be a close cousin - a precursor perhaps - of the electromagnetic field theory. Let us examine the advantages of taking the final step, from a version of the psychoneural identity theory which proposes that consciousness is identical with the spatiotemporally patterned firing of large masses of neurons, to the electromagnetic field theory which proposes that consciousness is identical with the patterns in the electromagnetic field produced by the firing of those neurons.
First, there is the issue of whether the firing of neurons per se can even be regarded as a member of the same category of phenomena as the subjective experience of the color blue. It simply does not seem to make intuitive or even logical sense to postulate identity between the subjective experience of blueness and the movement of ions into and out of cells in area V4 of the cerebral cortex. What does it mean to say that two entities are identical? Following Leibnitz's law as to the strict identity of indiscernables, to say that consciousness is identical with neural events is to say that these two possess all of their properties in common. But it seems patently obvious that the subjective experience of the color blue and the firing of action potentials in V4 have strikingly different properties, rather than all properties in common. On the other hand it seems more possible that the subjective experience of blueness should have all properties in common with a particular configuration of the electromagnetic field. Other configurations of the electromagnetic field apparently do have a wide variety of wonderful properties, so it seems not unreasonable that some configurations of the field should have the wonderful property of consciousness. In short, it simply seems less unlikely that a person should be identified with an everchanging, shimmering, invisible field that is spatially coincident with their brain than that they should be "nothing but a pack of neurons."
Secondly, the psychoneural identity theory implies that only neural tissue - and only certain kinds of neural tissue at that - can embody consciousness. In some sense this postulate necessarily involves "smuggling dualism in through the back door" as Globus puts it (Globus, 1973 [114]). What is it about matter that is organized as neural tissue that makes it potentially identical with consciousness, while matter organized in other ways is not? The psychoneural identity theory offers no clues. The electromagnetic field theory is not subject to this difficulty, however, as it admits the possibility that any kind of matter capable of generating the relevant configurations of the field could support consciousness.
None of the objections so far advanced against acceptance of the electromagnetic field theory of consciousness has much real force and certainly none of them even comes close to being fatal to the theory.