It might be a form of matter. This initially seems just plain wrong -- the very phrase "mind over matter" shows that intuitively we put the two in different categories. But intuition or folk psychology has a history of being wrong, and in fact there's a whole theory (initiated but now disparaged by philosophers, but still accepted as a given by many neurophysiologists) which essentially says that consciousness just IS the working brain. That's known as Psychoneural Identity Theory, rebranded by Francis Crick as "The Astonishing Hypothesis." For my taste there are rather too many holes in this idea. Not only does it intuitively seem wrong, it also demands that the matter making up conscious brains should somehow have radically different properties from the matter making up rocks, or tables, or speed-boats -- or single neurons kept alive in a dish, or recently deceased whole brains -- or even living brains that have been anesthetized. But none of the measurement techniques we have available can find any difference between the atoms and molecules that make up these various entities. So I don't find that theory at all satisfying. What are the other possibilities?
Consciousness might be "a process, not a thing." This one is called functionalism, and it's espoused by most psychologists. There have been huge debates about the validity of functionalism as a paradigm. As far as I can see it's fine for experiments designed to look at the processes underpinning cognition, but no good at all for studying consciousness. This makes it unsurprising that psychologists in general are functionalists, because it is only relatively recently that the discipline of psychology emerged from under the yoke of behaviorism, which basically denied the existence of consciousness altogether. Those psychologists who do now study consciousness tend to espouse functionalism because the father of psychology William James rightly pointed out that consciousness changes on a time scale of fractions of seconds. Things don't change on a time scale of fractions of seconds. Processes, or streams (as in ‘the stream of consciousness’) do.
Which brings us to the electromagnetic field theory of consciousness. The electromagnetic fields produced by working brains also change on a time scale of fractions of seconds. But unlike "processes" or "streams," electromagnetic fields are not abstractions -- they're real physical entities. Electromagnetic fields are LIKE things, but they're not material things. They can exist in the same physical space as material things. They're (relatively) easily measured. We know they're generated by functioning brains. We even know how they're generated by functioning brains. So my proposal is that some sorts of spatiotemporal electromagnetic patterns ARE consciousness.
MLU: And you have certainly done your homework with this unique and controversial theory. In your books and papers you have not only provided evidence to back up your thesis, you have also addressed criticism. Briefly, what objections have you encountered, and how have you responded?
SP: Probably the most common objection, the one everybody immediately thinks of, is that external electric or magnetic fields such as those produced by hairdryers, high tension power lines and MRI machines don't have any effects on consciousness. Of course it’s quite true that such external fields do not influence consciousness, but that can be seen as an objection only if you misunderstand the characteristics of the (putatively) conscious fields in the EM field theory of consciousness. In fact the theory specifically predicts that spatially unpatterned fields like those produced by hairdryers and so on will NOT influence consciousness. This is because, to use the terminology of physics, there is no coupling between these fields and the putatively conscious fields generated by the brain. The brain-generated fields are three-dimensional spatial patterns, which simply ride up and down on time-varying but spatially unpatterned external fields like boats on an ocean. In principle, it certainly should be possible to cancel the putatively conscious fields using an external field -- but to do this you would have to impose a external field that was precisely patterned with the inverse of the conscious field's spatial pattern. Since I don't yet know either the exact characteristics of any particular conscious field, or any sufficiently clever means of generating patterned external fields, I can't yet do that test of the theory. But fortunately I've recently realised that there is another method of cancelling the putatively conscious fields, which we'll come to later in the interview.