The Stance scanned

stance 23Dan Dennett famously based his view of consciousness on the intentional stance. According to him the attribution of intentions and other conscious states is a most effective explanatory strategy when applied to human beings, but that doesn’t mean consciousness is a mysterious addition to physics. He compares the intentions we attribute to people with centres of gravity, which also help us work out how things will behave, but are clearly not a new set of real physical entities.

Whether you like that idea or not, it’s clear that the human brain is strongly predisposed towards attributing purposes and personality to things. Now a new study by Spunt, Meyer and Lieberman using FMRI provides evidence that even when the brain is ostensibly not doing anything, it is in effect ready to spot intentions.

This is based on findings that similar regions of the brain are active both in a rest state and when making intentional (but not non-intentional) judgements, and that activity in the pre-frontal cortex of the kind observed when the brain is at rest is also associated with greater ease and efficiency in making intentional attributions.

There’s always some element of doubt about how ambitious we can be in interpreting what FMRI results are telling us, and so far as I can see it’s possible in principle that if we had a more detailed picture than FMRI can provide we might see more significant differences between the rest state and the attribution of intentions; but the researchers cite evidence that supports the view that broad levels of activity are at least a significant indicator of general readiness.

You could say that this tells us less about intentionality and more about the default state of the human mind. Even when at rest, on this showing, the brain is sort of looking out for purposeful events. In a way this supports the idea that the brain is never naturally quiet, and explains why truly emptying the mind for purposes of deep meditation and contemplation might require deliberate preparation and even certain mental disciplines.

So far as consciousness itself is concerned, I think the findings lend more support to the idea that having ‘theory of mind’ is an essential part of having a mind: that is, that being able to understand the probable point of view and state of knowledge of other people is a key part of having full human-style consciousness yourself.

There’s obviously a bit of a danger of circularity there, and I’ve never been sure it’s a danger that Dennett for one escapes. I don’t know how you attribute intentions to people unless you already know what intentions are. The normal expectation would be that I can do that because I have direct knowledge of my own intentions, so all I need to do is hypothesise that someone is thinking the way I would think if I were in their shoes. In Dennett’s theory, me having intentions is really just more attribution (albeit self-attribution), so we need some other account of how it all gets started (apparently the answer is that we assume optimal intentions in the light of assumed goals).

Be that as it may, the idea that consciousness involves attributing conscious states to ourselves is one that has a wider appeal and it may shed a slightly different light on the new findings. It might be that the base activity identified by the study is not so much a readiness to attribute intentions, but a continuous second-order contemplation of our own intentions, and an essential part of normal consciousness. This wouldn’t mean the paper’s conclusions are wrong, but it would suggest that it’s consciousness itself that makes us more ready to attribute intentions.

Hard to test that one because unconscious patients would not make co-operative subjects…

Measuring consciousness

measureThere were reports recently of a study which tested different methods for telling whether a paralysed patient retained some consciousness. In essence, PET scans seemed to be the best, better than fMRI or traditional, less technically advanced tests. PET scans could also pick out some patients who were not conscious now, but had a good chance of returning to consciousness later; though it has to be said a 74% success rate is not that comforting when it comes to questions of life and death.

In recent years doctors have attempted to diagnose a persistent vegetative state in unresponsive patients, a state i which a patient would remain alive indefinitely (with life support) but never resume consciousness; there seems to be room for doubt, though about whether this is really a distinct clinical syndrome or just a label for the doctor’s best guess.

All medical methods use proxies, of course, whether they are behavioural or physiological; none of them aspire to measure consciousness directly. In some ways it may be best that this is so, because we do want to know what the longer term prognosis is, and for that a method which measures, say, the remaining blood supply in critical areas of the brain may be more useful than one which simply tells you whether the patient is conscious now. Although physiological tests are invaluable where a patient is incapable of responding physically, the real clincher for consciousness is always behavioural; communicative behaviour is especially convincing. The Turing test, it turns out, works for humans as well as robots.

Could there ever be a method by which we measure consciousness directly? Well, if Tononi’s theory of Phi is correct, then the consciousness meter he has proposed would arguably do that. On his view consciousness is generated by integrated information, and we could test how integratedly the brain was performing by measuring the effect of pulses sent through it. Another candidate mught be possible if we are convinced by the EM theories of Johnjoe McFadden; since on his view consciousness is a kind of electromagnetic field, it ought to be possible to detect it directly, although given the small scales involved it might not be easy.

How do we know whether any of these tests is working? As I said, the gold standard is always behavioural: if someone can talk to you, then there’s no longer any reasonable doubt; so if our tests pick out just those people who are able to communicate, we take it that they are working correctly. There is a snag here, though: behavioural tests can only measure one kind of consciousness: roughly what Ned Block called access consciousness, the kind which has to do with making decisions and governing behaviour. But it is widely believed that there is another kind, phenomenal consciousness, actual experience. Some people consider this the more important of the two (others, it must be added, dismiss it as a fantasy). Phenomenal consciousness cannot be measured scientifically, because it has no causal effects; it certainly cannot be measured behaviourally, because as we know from the famous thought-experiment about  philosophical ‘zombies’ who lack it, it has no effect on behaviour.

If someone lost their phenomenal consciousness and became such a zombie, would it matter? On one view their life would no longer be worth living (perhaps it would be a little like having an unconscious version of Cotard’s syndrome), but that would certainly not be their view, because they would express exactly the same view as they would if they still had full consciousness. They would be just as able to sue for their rights as a normal person, and if one asked whether there was still ‘someone in there’ there would be no real reason to doubt it. In the end, although the question is valid, it is a waste of time to worry about it because for all we know anyone could be a zombie anyway, whether they have suffered a period of coma or not.

We don’t need to go so far to have some doubts about tests that rely on communication, though. Is it conceivable that I could remain conscious but lose all my ability to communicate, perhaps even my ability to formulate explicitly articulated thoughts in my own mind?  I can’t see anything absurd about that possibility: indeed it resembles the state I imagine some animals live their whole lives in. The ability to talk is very important, but surely it is not constitutive of my personal existence?

If that’s so then we do have a problem, in principle at least, because if all of our tests are ultimately validated against behavioural criteria, they might be systematically missing conscious states which ought not to be overlooked.