Archive for October, 2011

Zoned-out ratThe New Scientist suggests that zoned-out rats may give us a clue to consciousness.

It’s all to do with the Default Mode Network, or DMN. You might think that when we stop concentrating on a particular task and sit back for a few quiet minutes the level of activity in our brains would fall, but it turns out this isn’t really so: instead, more or less the same level of activity appears to continue, but it switches to a different set of areas – in particular, a linked set of areas in the cortex and elsewhere. This is the DMN, but what is it doing?

A completely honest answer, I think, would be that we don’t exactly know except that it’s something other than concentrating on a task.  In human subjects the DMN seems to be associated with daydreaming, but also with other detached modes of thought.  Why would this help explain consciousness? It seems that in patients with locked-in syndrome, where consciousness is fully retained but the patient is unable to move, the DMN is functioning normally, whereas in persistent vegetative syndrome, where consciousness is absent, it is disrupted.

I can think of a further reason to think that this might shed light on consciousness. It’s not much of a stretch to see DMN activity as being the kind of thinking that isn’t directly related to inputs and outputs. When we’re working on a task those are crucial, but one plausible account of the role of consciousness is exactly that it lets us escape from giving instant responses to our surroundings and lets us develop longer-term plans, deeper understanding, and more complex behaviour. If the DMN represents useful mental activity detached from inputs and outputs it is exactly the thing whose existence the behaviourists denied, which is pretty much the same as one conception of consciousness.

The New Scientist and others speak of the DMN as associated with introspection, but I can’t see the evidence for that. To be daydreaming or thinking in general terms about stuff that is or might be going on is not introspection. I think there’s some confusion going on here between thinking internally and thinking about what’s going on internally: and perhaps a further suggestion that introspection= self-awareness = consciousness: those are tenable but debatable equations which don’t seem to be vindicated or disproved by the mere existence of the DMN. So perhaps the excitement is premature.

The rats are not that reassuring either. The New Scientist reports that analogues of the human DMN have been found in monkeys, and now even in rats. That’s interesting, but unless we rate the consciousness of rats unusually highly it seems to show that the DMN  cannot explain any uniquely human level of consciousness. Fair enough: I don’t disdain rat consciousness altogether: but it’s worse than that because, as I understand it, the evidence currently suggests that younger human children don’t have an identifiable DMN. It would be somewhat weird to attribute to rats a level of reflective consciousness which is absent in human infants – wouldn’t it?  If more were needed to put us off, it is not quite 100% agreed that the DMN is in fact a functional entity in itself; it could yet turn out to be more like the mere absence of the TPN, the Task Positive Network which is its opposite (or complement) – the similar set of areas which appear to work together when we’re engaged in a specific task. Perhaps the level of neuronal activity in the brain stays high, not because the DMN is really processing anything, but because the brain just uses a lot of energy to tick over?

Still, if the DMN doesn’t explain what consciousness is, it’s hard to resist the view that it’s telling us something about how it works. Problems with the DMN have been put forward as possible causes of Alzheimer’s, autism, and schizophrenia (I think everything has been put forward as a possible cause of schizophrenia). The range of problems is perhaps an indication of the vagueness of the theories. There is some good evidence of a correlation between Alzheimer’s and disrupted DMN: but then the DMN includes quite a siginficant sampling of some important areas of the brain, so that may not mean all that much. It could be that when consciousness is disrupted the DMN tends naturally to get disrupted too, without that implying that the DMN actually runs or constitutes even the less-focused forms of consciousness.

At the end of the day what we’re left with is that our brains – and even rat brains – don’t use the same circuits for task-related and non-task related activity, but go through a fairly large-scale switch of resources.  Even if we’re idly daydreaming about driving into town already, it seems we bring in a different set of neurons to do it with. There has to be some good reason for this, but what…?

The latest issue of the JCS is all about pain.  Pain has always been tough to deal with: it’s subjective, not a thing out there in the world, and yet even the most hardline reductionist materialist can’t really dismiss it as an airy-fairy poetic delusion. We are all intensely concerned about pain, and the avoidance of it is among our most important moral and political projects. When you step back a bit, that seems remarkable: it’s easy to see more or less objective reasons why we should want to prevent disease, mitigate the effects of natural disasters, prevent wars and famines – harder to see why near or even at the top of the list of things we care about should be avoiding the occurrence of a particular kind of pattern of neuronal firing.

It’s hard even to say what it is. It seems to be a sensation, but a sensation of what? Of…. pain? Our other sensations give us information, about light, sound, temperature, and so on. Pain is often accompanied by feelings of pressure or heat or whatever, but it is quite distinct and separable from those impressions. In itself, the only thing pain tells us is: ‘you’re in pain’.  It seems sensible, therefore, to regard it as not a sensation in the same way as other sensations, but as being something like a kind of deferrable reflex: instead of just automatically moving our arm away from the hot pan it tells us urgently that we ought to do so. So it turns out to be something like a change in our dispositions or a change of weightings in our current projects.  That kind of account is appealing except for the single flaw of being evident nonsense.  When I’m in the dentist’s chair, I’m not feeling a change in my dispositions or anything that abstract, I’m feeling pain – that thing, that bad thing, you know what I mean, even though words fail me.

If it’s hard to describe, then, is pain actually the most undeniable of qualia? From some angles it looks like a quale, but qualia are supposed to have no causal effects on our behaviour, and that is exceptionally difficult to believe in the case of pain: if ever anything was directly linked to motivation, pain is it.  Undeniability looks more plausible: pain is pre-eminently one of the things it seems we can’t be wrong about. I might be mistaken in my belief that my hand has just been sheared off by a saw:  that ‘s a deduction about the state of the world based on the evidence of my senses; I don’t see how I could be wrong about the fact that I’m in agony because no reasoning is involved: I just am.

One of the contributors to the JCS might take issue with that, though. S. Benjamin Fink wants to present an approach to difficult issues of phenomenal experience and as his example he offers a treatment of pain which suggests it isn’t the simple unanalysable primitive we might think. In Fink’s view one of the dangers we need to guard against is the assumption that elements of experience we’ve always, as it happens, had together are necessarily a single phenomenon.  In particular, he wants to argue for the independence of pain and suffering/unpleasantness. Pain, it turns out, is not really bad after all (at least, not necessarily and in itself).

Fink offers several examples where pain and unpleasantness occur separately. An itch is unpleasant but not painful; the burning sensation produced by hot chillies is painful but not unpleasant (at least, so long as it occurs in the mouths of regular chili eaters, and not in their eyes or a neophyte’s mouth). These examples seem vulnerable to a counterargument based on mildness: itches aren’t described as pains just because they aren’t bad enough; and the same goes for spicy food in a mouth that has become accustomed to it. But Fink’s real clincher is the much more dramatic example of pain asymbolia. People with this condition still experience pain but don’t mind it. It’s not at all that they’re anaesthetised: they are aware of pain and can use it rationally to decide when some part of their body is in danger of damage, but they do so , as it were coldly, and don’t mind needles being stuck in them for experimental purposes at all. Fink quotes a woman who underwent a lobotomy to cure continual pain: many years later she reported happily that the pain was still there: “In fact, it’s still agonising. But I don’t mind.”

These people are clearly exceptional, but it’s worth noting that even in normal people the link between nociception, the triggering of pain-sensing nerve-endings, and the actual experience of pain is by no means as invariable and straightforward as philosophers used to believe back in the days when some argued that the firing of c-fibres was identical with the occurence of pain. Fink wants to draw a distinction between pain itself, a sensation, and suffering, the emotional response associated with it; it is the latter, in his view, which is the bad thing while pain itself is a mere colourless report. As a further argument he notes research which seems to show that when subjects are feeling compassion, some neural activity can be seen in areas which are normally active when the subjects themselves are feeling pain. The subjects, as it were, feel the the pain of others, though obviously without actual nociception.

So is Fink right? I think many people’s first reaction might be that unpleasantness just defines pain, so that if you’re feeling something that isn’t unpleasant, we wouldn’t want to call it pain. We might say that people with asymbolia experience nocition (not sure that’s really a word but work with me on this) but not pain. Fink would say – he does say – that we ought to listen to what people say. Usage should determine our definition, he says, we should not make our definitions normatively control our usage.  But he’s in a weak position here. If we are to pay attention to usage, then surely we should pay attention to the usage of the vast majority of people who regard pain as a unitary phenomenon, not to a small group of people with a most unusual set of experiences which might have tutored their perceptions in unreliable ways. I’m not sure it’s clear that asymbolics, in any case, insist that what they’re aware of is proper, echt pain – if they were asked, would they perhaps agree that it’s not pain in quite the ordinary sense?

I’m also not convinced that suffering, or unpleasantess, is really a well-defined entity in the way Fink requires. Unpleasantness may be a slight lapse of manners at a tea-party;  you might suffer badly on the stock exchange while happily sipping a cocktail on your sun-lounger. I’m not sure there is a distinct complex of emotional affect we can label as suffering at all. And if there is, we’re back with the sheer implausibility of saying that that’s what the bad stuff is: when I hit my thumb with a hammer it doesn’t seem like a matter of affect to me, it seems very definitely like old-fashioned simple pain.

If we’re going to take that line, though, we have to account for Fink’s admittedly persuasive examples, in particular asymbolia.  Never mind now what we call it: how is it that these people can experience something they’re willing to call pain without minding it, if it isn’t that our concept of pain needs reform?

Well, there is one other property of pain which we’ve overlooked so far.  There is one obvious kind of pain which I can perceive without being disturbed at all – yours. We may indeed feel some sympathetic twinges for the pain of others, but a key point about pain is that it’s essentially ours. It sticks to us in a way nothing else does: it’s normal in philosophy to speak of the external world, but pain, perhaps uniquely, isn’t external in that sense: it’s in here with us.  That may be why it has another property, noted by Fink, of being very difficult to ignore.

So it may be that subjects with asymbolia are not lacking emotional affect, but rather any sense of ownership. The pain they feel is external, it’s not particularly theirs: like Mrs Gradgrind they feel that

‘… there’s a pain somewhere in the room, but I couldn’t positively say that I have got it.’

 

 

OEDWhat do we even mean when we speak of consciousness? As we’ve noted before, there are many competing and overlapping definitions, and in addition it’s pretty clear that the phenomenon itself is complex and that the word refers, in different contexts, to a number of different things.

A few years back, Thomas Natsoulas had a determined go at clarifying the position in his paper “Concepts of Consciousness”.  For his framework he fell back on the old debating society standby of consulting the dictionary. You might ask whether this was necessarily the best way to go: lexicographers have their own priorities, after all. They typically aim to report the way a word is used; if it’s used in ways that are inconsistent or taxonomically incomplete, that isn’t a problem for them. On the other hand, the use of dictionary definitions does bring in an element of neutrality, and protects Natsoulas against any charge of skewing his definitions to support his own theoretical views: and the dictionary in question was no less a tome than the complete Oxford English Dictionary (OED), a mighty work of scholarship whose views on almost any subject are not to be lightly dismissed. Natsoulas himself says he sees merit in looking at ordinary, common-sense ideas, which can help remedy the potentially problematic lack of work by psychologists on the conceptual side.

The OED gives six senses of ‘consciousness’. The first, which we can call c1, strikes a modern reader as odd: it is knowing something together, joint or shared knowledge: con-scire as the derivation of the word suggests. There is a definite suggestion of the shared knowledge being a guilty secret, perhaps even an echo of con-spire. Although c1 is the ancient sense of the Latin root and seems to have enjoyed a brief revival in the seventeenth century it is no longer current and does not at first seem to offer us much enlightenment on the modern concept. Natsoulas, however, points out that it captures the idea of consciousness as a social, interpersonal thing. He quotes Barlow:

…consciousness is something to do with a relation between brains rather than a property of a single brain.

Barlow, it seems, went on to suggest that internal consciousness was a kind of ‘rehearsal for recounting’, which is interesting.

If we doubt that c1 is really important, I suppose we might ask ourselves what the state of mind would be of a human being who never at any stage since birth met another communicative entity. I don’t think I’d be ready to say that such a person could not be conscious, but their consciousness would surely be lacking in some important respects.

C2 follows on in a way: it is in effect knowledge shared with oneself, knowing that you know. This sounds like the HOT (Higher Order Theory) and HOP (Higher Order Process) theories which approximately say that a thought is conscious when accompanied by an awareness of that thought. It’s also reminiscent of those, like Dennett, who see the internalisation of talking to oneself as the origin of consciousness.

Natsoulas quotes Vygotsky:

 A function which initially was shared by two people and bore a character of communication between them gradually crystallised and became a means of organisation of the mental life of man himself

It almost begins to look as if the OED has a rather cogent theory of consciousness.

C3 is awareness, of or that, anything, whether obects in the world or one’s own thoughts. Natsoulas insists there must be an object for this form of consciousness: even the thought that ‘I am having no thoughts’ actually has a content, he points out. Being conscious without content is in his eyes properly reserved for c6. He notes that the OED seems to include with c3 a veridicality requirement the claim is that if a man is aware of a bush, but thinks it is a rabbit, he is not really aware of the bush. Natsoulas, rightly I think, disagrees, insisting that even false awareness is still awareness. I think we must certainly preserve the possibility of being aware of something without having to have correct knowledge of its real nature.

I’m not sure whether the indirect awareness of memory falls into this category or the next, but there seems to be an overlap because c4 is, to adopt the OED’s Locke quotation:

…the perception of what passes in a man’s own mind…

which appears to be a subset of c3. Interestingly the OED seems to think that the primary use of c3 is awareness of one’s own mental contents, while using it to mean awareness of actual objects in the world is ‘poetic’. Natsoulas concludes that in this respect Englsh has moved on a bit since the OED last looked, but you have to admire the magisterial coherence of the OED view in which consciousness begins by being shared knowledge, becomes knowledge you share with yourself, in which form it is naturally about your own internal states, but by metaphorical extension can also mean your awareness of the external world.

I say c4 seems to be a subset of c3: perhaps as a result, Natsoulas says experimenters are often bedevilled by confusion between the two, claiming that a subject’s inability to report a stimulus shows they were never aware of it (whereas the subject can be aware of the stimulus withoug being aware that they are aware).

There might seem to be some dangers in the self-reference of c4,  but Natsoulas points out that there’s no problem in well-managed higher orders. If there were a ban on higher orders, he argues, introspection could never get properly started.

c5 is not a form of consciousness but rather a set of all the occurrent and previous mental states which putatively make up the individual’s existence. This is the sense in which science fiction stories speak of your consciousness being transferred to another body, or to a machine. The OED gives us a quote from Locke:

If the same consciousness can be transferr’d from one thinking substance to another, it will be possible that two thinking substances may make  but one person…

Natsoulas is quite happy with the idea that consciousness is not to be identified with the substrate, Locke’s ‘thinking substance’, but he raises some difficulties. What set of states is adequate to constitute a specific consciousness? Must it be all of them? That seems too strong, because if I were to lose one of my memories, I should not thereby lose my identity – I forget things all the time. Perhaps it has to everything I could recall – and some forgotten or unconscious things might still be shaping my mind. Worse, I can remember experiences yet fail to have the feelng that they are really my experiences.

Some would regard this defining set of mental states as the ego, or the ‘I’, which is a way of looking at it: but attempts to use a static central ‘I’ as the thing that pulls it all together are doomed in Natsoulas’ eyes. He thinks that with appropriate care we can use c5 and take account of the vivid and persuasive sense of an inner source without having to grant its ontological reality.

c6 is approximately equivalent to ‘awake’ and the opposite of unconscious. Searle, in typical commonsensical style, once used c6 as his definition of consciousness:

‘Consciousness’ refers to those states of sentience and awareness that typically begin when we awake from a dreamless sleep and continue until we go to sleep again, or fall into a coma or die or otherwise become ‘unconscious’.

Natsoulas takes this to be the kind of consciousness that has no requirement as to content: you could be conscious in this sense while thinking anything or nothing. In fact although the medical salience of the concept is clear, it seems too open-ended to be of much analytical use.  We should certainly be willing to speak of a dog being conscious (or unconscious) in this sense, and I think we’d be willing to push that usage much further – certainly to fish and quite possibly to an ant in certain circumstances. We’re not, then, speaking of anything narrowly defined: c6 means something like ‘the state when whatever mental activity normally goes on during periods of activity, is going on’.

I think it is open to debate whether this OED-based six-way definition gives us sufficient tools to tackle the probem of consciousness. It does not seem to capture Ned Block’s distinction between a- and p-consciousness, more or less the distinction between the targets of the Hard and Easy problem: yet that is one of the most-quoted and used of definitions.  I think we might also look for sharper and more useful distinctions between internal and external awareness.

Still, it is a useful exercise, and Natsoulas proceeds to do something with the results, positioning the six senses along four different axes:  intersubjectivity, objectivation, apprehension and introspection (this seems to cry out for a diagram, though I appreciate that rendering a four-dimensional space graphically intelligible is a non-trivial matter.

Natsoulas makes little of this concluding exercise, presenting it as a kind of run-through to help get things clear. But it seems obvious that what he’s offering is a potential reduction, abstracting away from the six OED definitions to define a consciousness space of four dimensions. Not the least interesting aspect of this is that it implies the conceptual possibility of unknown forms of consciousness which would be situated in unpopulated regions of the space. Suppose, for example, we have a form of consciousness with high intersubjectivity, but low objectivation, apprehension, and introspection? My imagination begins to fail me, but I think that would be a kind of diffuse but powerful general empathy. I’m surprised this aspect has not been explored.