Archive for October, 2014

TegmarkEarlier this year Tononi’s Integrated Information Theory (IIT) gained a prestigious supporter in Max Tegmark, professor of Physics at MIT. The boost for the theory came not just from Tegmark’s prestige, however; there was also a suggestion that the IIT dovetailed neatly with some deep problems of physics, providing a neat possible solution and the kind of bridge between neuroscience, physics and consciousness that we could hardly have dared to hope for.

Tegmark’s paper presents the idea rather strangely, suggesting that consciousness might be another state of matter like the states of being a gas, a liquid, or solid.  That surely can’t be true in any simple literal sense because those particular states are normally considered to be mutually exclusive: becoming a gas means ceasing to be a liquid. If consciousness were another member of that exclusive set it would mean that becoming conscious involved ceasing to be solid (or liquid, or gas), which is strange indeed. Moreover Tegmark goes on to name the new state ‘perceptronium’ as if it were a new element. He clearly means something slightly different, although the misleading claim perhaps garners him sensational headlines which wouldn’t be available if he were merely saying that consciousness arose from certain kinds of subtle informational organisation, which is closer to what he really means.

A better analogy might be the many different forms carbon can take according to the arrangement of its atoms: graphite, diamond, charcoal, graphene, and so on; it can have quite different physical properties without ceasing to be carbon. Tegmark is drawing on the idea of computronium proposed by Toffoli and Margolus. Computronium is a hypothetical substance whose atoms are arranged in such a way that it consists of many tiny modules capable of performing computations.  There is, I think, a bit of a hierarchy going on here: we start by thinking about the ability of substances to contain information; the ability of a particular atomic matrix to encode binary information is a relatively rigorous and unproblematic idea in information theory. Computronium is a big step up from that: we’re no longer thinking about a material’s ability to encode binary digits, but the far more complex functional property of adequately instantiating a universal Turing machine. There are an awful lot of problems packed into that ‘adequately’.

The leap from information to computation is as nothing, however, compared to the leap apparently required to go from computronium to perceptronium. Perceptronium embodies the property of consciousness, which may not be computational at all and of which there is no agreed definition. To say that raises a few problems is rather an understatement.

Aha! But this is surely where the IIT comes in. If Tononi is right, then there is in fact a hard-edged definition of consciousness available: it’s simply integrated information, and we can even say that the quantity required is Phi. We can detect it and measure it and if we do, perceptronium becomes mathematically tractable and clearly defined. I suppose if we were curmudgeons we might say that this is actually a hit against the IIT: if it makes something as absurd as perceptronium a possibility, there must be something pretty wrong with it. We’re surely not that curmudgeonly, but there is something oddly non-dynamic here. We think of consciousness, surely, as a process, a  function: but it seems we might integrate quite a lot of information and simply have it sit there as perceptronium in crystalline stillness; the theory says it would be conscious, but it wouldn’t do anything.  We could get round that by embracing the possibility of static conscious states, like one frame out of the movie film of experience; but Tegmark, if I understand him right, adds another requirement for consciousness: autonomy, which requires both dynamics and independence; so there has to be active information processing, and it has to be isolated from outside influence, much the way we typically think of computation.

The really exciting part, however,  is the potential linkage with deep cosmological problems – in particular the quantum factorisation problem. This is way beyond my understanding, and the pages of equations Tegmark offers are no help, but the gist appears to be that  quantum mechanics offers us a range of possible universes.  If we want to get ‘physics from scratch’, all we have to work with is, in Tegmark’s words,

two Hermitian matrices, the density matrix p encoding the state of our world and the Hamiltonian H determining its time-evolution…

Please don’t ask me to explain; the point is that the three things don’t pin down a single universe; there are an infinite number of acceptable solutions to the equations. If we want to know why we’ve got the universe we have – and in particular why we’ve got classical physics, more or less, and a world with an object hierarchy – we need something more. Very briefly, I take Tegmark’s suggestion to be that consciousness, with its property of autonomy, tends naturally to pick out versions of the universe in which there are similarly integrated and independent entities – in other words the kind of object-hierarchical world we do in fact see around us. To put it another way and rather baldly, the universe looks like this because it’s the only kind of universe which is compatible with the existence of conscious entities capable of perceiving it.

That’s some pretty neat footwork, although frankly I have to let Tegmark take the steering wheel through the physics and in at least one place I felt a little nervous about his driving. It’s not a key point, but consider this passage:

Indeed, Penrose and others have speculated that gravity is crucial for a proper understanding of quantum mechanics even on small scales relevant to brains and laboratory experiments, and that it causes non-unitary wavefunction collapse. Yet the Occam’s razor approach is clearly the commonly held view that neither relativistic, gravitational nor non-unitary effects are central to understanding consciousness or how conscious observers perceive their immediate surroundings: astronauts appear to still perceive themselves in a semi-classical 3D space even when they are effectively in a zero-gravity environment, seemingly independently of relativistic effects, Planck-scale spacetime fluctuations, black hole evaporation, cosmic expansion of astronomically distant regions, etc

Yeah… no. It’s not really possible that a professor of physics at MIT thinks that astronauts float around their capsules because the force of gravity is literally absent, is it? That kind of  ‘zero g’ is just an effect of being in orbit. Penrose definitely wasn’t talking about the gravitational effects of the Earth, by the way; he explicitly suggests an imaginary location at the centre of the Earth so that they can be ruled out. But I must surely be misunderstanding.

So far as consciousness is concerned, the appeal of Tegmark’s views will naturally be tied to whether one finds the IIT attractive, though they surely add a bit of weight to that idea. So far as quantum factorisation is concerned, I think he could have his result without the IIT if he wanted: although the IIT makes it particularly neat, it’s more the concept of autonomy he relies on, and that would very likely still be available even if our view of consciousness were ultimately somewhat different. The linkage with cosmological metaphysics is certainly appealing, essentially a sensible version of the Anthropic Principle which Stephen Hawking for one has been prepared to invoke in a much less attractive form

grazianoYes: I feel pretty sure that anyone reading this is indeed conscious. However, the NYT recently ran a short piece from Michael S. A. Graziano which apparently questioned it. A fuller account of his thinking is in this paper from 2011; the same ideas were developed at greater length in his book Consciousness and the Social Brain

I think the startling headline on the NYT piece misrepresents Graziano somewhat. The core of his theory is that awareness is in some sense a delusion, the reality of which is simple attention. We have ways of recognising the attention of other organisms, and what it is fixed on (the practical value of that skill in environments where human beings may be either hunters or hunted is obvious): awareness is just our garbled version of attention. he offers the analogy of colour. The reality out there is different wavelengths of light: colour, our version of that, is a slightly messed-up, neatened, artificial version which is nevertheless very vivid to us in spite of being artificial to a remarkably large extent.

I don’t think Graziano is even denying that awareness exists, in some sense: as a phenomenon of some kind it surely does: what he means is more that it isn’t veridical: what it tells us about itself, and what it tells us about attention, isn’t really true. As he acknowledges in the paper, there are labelling issues here, and I believe it would be possible to agree with the substance of what he says while recasting it in terms that look superficially much more conventional.

Another labelling issue may lurk around the concept of attention. On some accounts, it actually presupposes consciousness: to direct one’s attention towards something is precisely to bring it to the centre of your consciousness. That clearly isn’t what Graziano means: he has in mind a much more basic meaning. Attention for him is something simple like having your sensory organs locked on to a particular target. This needs to be clear and unambiguous, because otherwise we can immediately see potential problems over having to concede that cameras or other simple machines are capable of attention; but I’m happy to concede that we could probably put together some kind of criterion, perhaps neurological, that would fit the bill well enough and give Graziano the unproblematic materialist conception of attention that he needs.

All that looks reasonably OK as applied to other people, but Graziano wants the same system to supply our own mistaken impression of awareness. Just as we track the attention of others with the false surrogate of awareness, we pick up our own attentive states and make the same kind of mistake. This seems odd: when I sense my own awareness of something, it doesn’t feel like a deduction I’ve made from objective evidence about my own behaviour: I just sense it.  I think Graziano actually wants it to be like that for other people too. He isn’t talking about rational, Sherlock Holmes style reasoning about the awareness of other people, he has in mind something like a deep, old, lizard-brain kind of thing; like the sense of somebody there that makes the hairs rise on the back of the neck  and your eyes quickly saccade towards the presumed person.

That is quite a useful insight, because what Graziano is concerned to deny is the reality of subjective experience, of qualia, in a word. To do so he needs to be able to explain why awareness seems so special when the reality is nothing more than information processing. I think this remains a weak spot in the theory, but the idea that it comes from a very basic system whose whole function is to generate a feeling of ‘something there’ helps quite a bit, and is at least moderately compatible with my own intuitions and introspections.What Graziano really relies on is the suggestion that awareness is a second-order matter: it’s a cognitive state about other cognitive states, something we attribute to ourselves and not, as it seems to be, directly about the real world. It just happens to be a somewhat mistaken cognitive state.

That still leaves us in some difficulty over the difference between me and other people. If my sense of my own awareness is generated in exactly the same way as my sense of the awareness of others, it ought to seem equally distant  – but it doesn’t, it seems markedly more present and far less deniable.

More fundamentally, I still don’t really see why my attention should be misperceived. In the case of colours, the misrepresentation of reality comes from two sources, I think. One is the inadequacy of our eyes; our brain has to make do with very limited data on colour (and on distance and other factors) and so has to do things like hypothesising yellow light where it should be recognising both red and green, for example. Second, the brain wants to make it simple for us and so tries desperately to ensure that the same objects always look the same colour, although the wavelengths being received actually vary according to conditions. I find it hard to see what comparable difficulties affect our perception of attention. Why doesn’t it just seem like attention? Graziano’s view of it as a second-order matter explains how it can be wrong about attention, but not really why.

So I think the theory is less radical than it seems, and doesn’t quite nail the matter on some important points: but it does make certain kinds of sense and at the very least helps keep us roused from our dogmatic slumbers. Here’s a wild thought inspired (but certainly not endorsed) by Graziano. Suppose our sense of qualia really does come from a kind of primitive attention-detecting module. It detects our own attention and supplies that qualic feel, but since it also (in fact primarily) detects other people’s attention, should it not also provide a bit of a qualic feel for other people too? Normally when we think of our beliefs about other people, we remain in the explicit, higher realms of cognition: but what if we stay at a sort of visceral level, what if we stick with that hair-on-the back-of the-neck sensation? Could it be that now and then we get a whiff of other people’s qualia? Surely too heterodox an idea to contemplate…

gapWe’re often told that when facing philosophical problems, we should try to ‘carve them at the joints’. The biggest joint on offer in the case of consciousness has seemed to be the ‘explanatory gap’ between the physical activity of neurons and the subjective experience of consciousness. Now, in the latest JCS, Reggia, Monner, and Sylvester suggest that there is another gap, and one where our attention should rightly be focussed.

They suggest that while the simulation of certain cognitive processes has proceeded quite well, the project of actually instantiating consciousness computationally has essentially got nowhere.  That project, as they say, is affected by a variety of problems about defining and recognising success. But the real problem lies in an unrecognised issue: the computational explanatory gap. Whereas the explanatory gap we’re used to is between mind and brain, the computational gap is between high-level computational algorithms and low-level neuronal activity. At the high level, working top-down, we’ve done relatively well in elucidating how certain kinds of problem-solving, goal-directed kinds of computation work, and been able to simulate them relatively effectively.  At the neuronal, bottom-up level we’ve been able to explain certain kinds of pattern-recognition and routine learning systems. The two different kinds of processing have complementary strengths and weaknesses, but at the moment we have no clear idea of how one is built out of the other. This is the computational explanatory gap.

In philosophy, the authors plausibly claim, this important gap has been overlooked because in philosophical terms these are all ‘easy problem’ matters, and so tend to be dismissed as essentially similar matters of detail. In psychology, by contrast, the gap is salient but not clearly recognised as such: the lower-level processes correspond well to those identified as sub-conscious, while the higher-level ones match up with the reportable processes generally identified as conscious.

If Reggia, Monner and Sylvester are right, the well-established quest for the neural correlates of consciousness has been all very well, but what we really need is to bridge the gap by finding the computational correlates of consciousness. As a project, bridging this gap looks relatively promising, because it is all computational. We do not need to address any spooky phenomenology, we do not need to wonder how to express ‘what it is like’, or deal with anything ineffable; we just need to find the read-across between neural networking and the high-level algorithms which we can sort of see in operation. That may not be easy, but compared to the Hard Problem it sounds quite tractable. If solved, it will deliver a coherent account right from neural activity through to high-level decision making.

Of course, that leaves us with the Hard Problem unsolved, but the authors are optimistic that success might still banish the problem. They draw an analogy with artificial life: once it seemed obvious that there was a mysterious quality of being alive, and it was unclear how simple chemistry and physics could ever account for it. That problem of life has never been solved in terms, but as our understanding of the immensely subtle chemistry of living things has improved, it has gradually come to seem les and less obvious that it is really a problem. In a similar way the authors hope that if the computational explanatory gap can be bridged, so that we gradually develop a full account of cognitive processes from the ground-level firing of neurons up to high-level conscious problem-solving, the Hard Problem will gradually cease to seem like something we need to worry about.

That is optimistic, but not unreasonably so, and I think the new perspective offered is a very interesting and plausible one. I’m convinced that the gap exists and that it needs to be bridged: but I’m less sure that it can easily be done.  It might be that Reggia, Monner, and Sylvester are affected in a different way by the same kind of outlook they criticise in philosophers: these are all computational problems, so they’re all tractable. I’m not sure how we can best address the gap, and I suspect it’s there not just because people have failed to recognise it, but because it is also genuinely difficult to deal with.

For one thing, the authors tend to assume the problem is computational. It’s not clear that computation is of the essence here. The low-level processes at a neuronal level don’t look to be based on running any algorithm – that’s part of the nature of the gap. High-level processes may be capable of simulation algorithmically, but that doesn’t mean that’s the way the brain actually does it. Take the example of catching a ball – how do we get to the right place to intercept a ball flying through the air?  One way to do this would be some complex calculations about perspective and vectors: the brain could abstract the data, do the sums, and send back the instructions that result. We could simulate that process in a computer quite well. But we know – I think – that that isn’t the way it’s actually done: the brain uses a simpler and quicker process which never involves abstract calculation, but is based on straight matching of two inputs; a process which incidentally corresponds to a sub-optimal algorithm, but one that is good enough in practice. We just run forward if the elevation of the ball is reducing and back if it’s increasing. Fielders are incapable of predicting where a ball is going, but they can run towards the spot in such a way as to be there when the ball arrives.  It might be that all the ‘higher-level’ processes are like this, and that an attempt to match up with ideally-modelled algorithms is therefore categorically off-track.

Even if those doubts are right, however, it doesn’t mean that the proposed re-framing of the investigation is wrong or unhelpful, and in fact I’m inclined to think it’s a very useful new perspective.

 

pixelated eyeYou’ve heard of splitting the atom: W. Alex Escobar wants to split the quale. His recent paper (short article here) proposes that in order to understand subjective experience we may need to break it down into millions of tiny units of experience.  He proposes a neurological model which to my naive eyes seems reasonable: the extraordinary part is really the phenomenology.

Like a lot of qualia theorists Escobar seems to have based his view squarely on visual experience, and the idea of micro-qualia is perhaps inspired by the idea of pixels in digitised images, or other analytical image-handling techniques.  Why would the idea help explain qualia?

I don’t think Escobar explains this very directly, at least from a philosophical point of view, but you can see why the idea might appeal to some people. Panexperientialists, for example, take the view that there are tiny bits of experience everywhere, so the idea that our minds assemble complex experiences out of micro-qualia might be quite congenial to them.  As we know, Christof Koch says that consciousness arises from the integration of information, so perhaps he would see Escobar’s theory as offering a potentially reasonable phenomenal view of the same process.

Unfortunately Escobar has taken a wrong turning, as others have done before, and isn’t really talking about ineffable qualia at all: instead, we might say he is merely effing the effable.

Ineffability, the quality of being inexpressible, is a defining characteristic of qualia as canonically understood in the philosophical literature. I cannot express to you what redness is like to me; if I could, you would be able to tell whether it was the same as your experience. If qualia could be expressed, my zombie twin  (who has none) would presumably become aware of their absence; when asked what it was like to see red, he would look puzzled and admit he didn’t really know, whereas ex hypothesi he gives the same fluent and lucidly illuminating answers that I do – in spite of not having the things we’re both talking about.

Qualia, in fact, have no causal effects and cannot be part of the scientific story. That doesn’t mean Escobar’s science is wrong or uninteresting, just that what he’s calling qualia aren’t really the philosophically slippery items of experience we keep chasing in vain in our quest for consciousness.

Alright, but setting that aside, is it possible that real qualia could be made up of many micro-qualia? No, it absolutely isn’t! In physics, a table can seem to be a single thing but actually be millions of molecules.  Similarly, what looks like a flat expanse of uniform colour on a screen may actually be thousands of pixels. But qualia are units of experience; what they seem like is what they are. They don’t seem like a cloud of micro-qualia, and so they aren’t. Now there could be some neuronal or psychological story going on at a lower level which did involve micro units; but that wouldn’t make qualia themselves splittable. What they are like is all there is to them; they can’t have a hidden nature.

Alas, Escobar could not have noticed that, because he was too busy effing the Effable.