Archive for January, 2008

Picture: David. It often happens that when someone has had a limb amputated, they experience feelings in the limb they haven’t got any more – the ‘phantom limb’ phenomenon. The phantoms may be just temporary, a curious by-product of the operation. Sometimes the feelings are partial – where an arm has been removed, for example, patients may feel as though they still had their hand, but attached to the shoulder without any intervening arm. Sometimes the experience is more of a problem, with feelings of intense pain in the amputated part which won’t go away and can’t be treated by normal means.

I therefore winced slightly on learning that as well as phantom limbs, there are phantom penises, experienced by those who have undergone a penectomy (a word which is well worthy of a wince in itself). V.S.Ramachandran, who devised an ingenious way of using mirrors to help people with phantom limb pain, by fooling the brain into briefly believing that the missing limb was back, has now turned his attention to penises, together with P.D. McGeoch. This time the research is not about pain relief, however, but gender identity, where the possession or lack of a penis is clearly highly relevant.
Penectomies, it seems, are performed for two main reasons; to eliminate a malignant cancer, or as part of gender reassignment treatment. Since male-to-female transsexuals typically feel themselves to be ‘a woman in a man’s body’, Ramachandran and McGeoch reasoned that their response to penectomy might well be different from that of other patients. And so it proved: while 58% of men who have undergone penectomy for other reasons reported sensation in a phantom penis afterwards, only 30% of those who had done so as part of gender reassignment had a similar experience. So people who felt that a penis was not part of their true body image were much less likely to experience a phantom penis after removal.

Stranger still, perhaps, 62% of a group of female-to-male transsexuals reported having had phantom penis sensations before any surgery. In many cases the sensations dated back for years: in others, they did not occur until hormone treatment had begun. No non-transsexual women, unsurprisingly, reported the sensation of having a phantom penis (‘even when prompted’ as the researchers say).
Ramachandran and McGeoch conclude that the study backs the view that gender identity feelings are hard-wired into the brain, and in transsexuals may be at odds with actual physical shape. They recognise, however, that there are some potential criticisms of the way the research was done.

One weak point is the risk of confabulation. By asking female-to-male transsexuals whether they had ever had phantom penis sensations, were the researchers discovering a phenomenon, or creating one? Transsexuals often have to struggle for the acceptance of their view of themselves; they have a natural reason to want to assert anything that might strengthen their case. The experience of a phantom penis would clearly be a useful piece of evidence in this context. Since female-to-male transsexuals by definition feel that they ought to have a penis, it may not be much of a leap to say they feel as though they have one, once the possibility is suggested.

To some extent, moreover, male-to-female transsexuals might have been inclined to feel that any report of phantom sensations was letting the side down in some subtle way; suggesting that they or their bodies somehow couldn’t give up the idea of having a penis very readily. Indeed, an old Freudian theory which the researchers pour scorn on, had it that the symptoms of phantom limbs expressed an unconscious desire that the limb was still there, so reasoning along those lines is by no means impossible.

However, the researchers have a number of counterarguments. Perhaps the most striking is that female-to-male transsexuals were often able to report details of the phantom penis and its behaviour, saying that it fell short of their ideal penis, for example. Surely an imagined penis, a wish-fulfilment penis, would be fully satisfactory? Less convincingly, I think, the researchers quote cases where the subjects reported the phantom penis behaving in ways – morning or unprompted erections, for example – which a female subject allegedly would have been unlikely to add to a confabulated account. I suspect the female subjects are likely to have been more aware of this kind of detail than the researchers suppose.

At the end of the day, we seem to have some suggestive evidence, but not a fully convincing case. Ramachandran and McGeoch rightly say that evidence from brain imaging studies would be very useful – notably in establishing whether a pre-operative female-to-male transsexual having a phantom penis experience has similar brain activity to a male having normal penis sensations.

Picture: egocentric.

The hypothesis that human beings have not one, but two distinct visual systems, now seems to be widely accepted. There are certainly convincing stories to be told about it both in neurological and functional terms. Neurologically, it seems that two different streams draw on the information provided by the primary visual area of the brain. A ventral stream goes eventually to the inferior temporal cortex, while a dorsal stream goes to the posterior parietal lobe. The brain being what it is, things are not quite that simple, of course, and the two streams are not completely isolated, but there seems to be good enough reason to think of the them as essentially independent.Functionally, there is evidence that the brain deals separately with conscious visual perception on the one hand and ‘automatic’ control of actions on the other. The former system, for example, is easier to fool than the latter. When presented with certain kinds of geometrical optical illusion, we may be deceived consciously about the apparent size of an object, but when we reach out to take the object, our fingers open to just the right size anyway. There’s also evidence from the effects of injuries: damage to the relevant regions of the brain may damage our conscious awareness while leaving us apparently able to use our eyes for practical purposes. Perhaps the most extreme cases are the famous instances of blindsight; subjects who cannot see at all so far as their conscious minds are concerned, but who can point to an object, or reach for one, with much greater accuracy than chance guesses could provide. Ramachandran, for one, has suggested that the two visual streams provide a satisfying answer to the puzzle of blindsight.

It is therefore an attractive hypothesis that the two streams serve regions of the brain with complementary roles, one delivering conscious visual experience and the other feeding into accurate motor control; one stream telling you what, and the other where, as some describe it. It seems to me, incidentally, that there is an interesting side-implication here about our fellow primates. Since they have the same two-stream system (in fact, I believe it was originally discovered in macaques), the implication is that they must have the same experience of doing some things deliberately, and others unthinkingly. We might have been tempted to think that animals, relying on instinct, operate on a kind of permanent autopilot, always in the same sort of state we are in when walking along without thinking of where we’re going; but that seems to be ruled out at least as far as primates are concerned.

Be that as it may, a further step has been taken by many researchers, who propose that the two visual systems must encode information differently. The system which delivers conscious perception, drawing on the ventral stream, must surely encode the positions of objects allocentrically, ie in relation to the scene before us, rather than egocentrically, ie plotting distance and direction from the observer. Since this system is concerned above all with identifying things, it’s surely most helpful to have things encoded in a way that doesn’t change every time we move around the room, they argue. In the case of the other system, where the top priority is such tasks as deciding how far to extend your arm in order to grab something, an egocentric scheme of coding makes more sense. This view is buttressed by an argument that the allocentric coding of the perception system is what makes it more vulnerable to optical illusions.

However, in a paper for Philosophy and Phenomenological Research, Robert Briscoe now rides to the rescue of egocentricity. He thinks that our conscious perception can perhaps be regarded in this respect as an extension of proprioception, the special sense which tells us where the different parts of our body are; and both, he claims, are plausibly based on an egocentric coding scheme.

He dissociates himself from two positions which appear to have been severely undercut by the two-systems hypothesis. The first, Experience-Based Control (EBC) asserts that our fine motor control draws on the richness of our conscious perception (not all of which necessarily gets our full attention); the other, the Grounding Hypothesis, is even stronger, claiming that it is necessarily grounded in conscious experience. All such views are rejected by Briscoe, which leaves him free to sidestep the evidence which tells against them. Turning to the arguments based on optical illusion, he argues that the undeniably greater vulnerability of conscious experience might not stem from allocentric coding, but from the diversity of sources drawn on by conscious experience, and hence be attributable to difficulties with integration.

And after all, he concludes, moving from defence to attack, the two systems do in fact communicate and co-operate, with conscious experience identifying the targets and the other stream sorting out the details of the movements required. If they use different coding schemes to represent the positions of objects, there are going to be some problems of translation which don’t arise if both systems are egocentric.

This all seems fairly convincing to me, but I wonder whether the dispute will eventually turn out to have been misconceived: one of those either/or disputes where neither hypothesis actually catches the truth properly. Perhaps allocentric and egocentric coding aren’t really the only alternatives and one or both systems operate on some mixed, intermediate,or entirely different principle. In fact, Briscoe’s own views hint at this to some degree. In his view, conscious perception is an extension of proprioception; but proprioception does not, he says relate everything to some arbitrary central point – rather, it relates different body parts to each other. If we extend that approach to the external world, we seem to get a system which relates objects to each other rather than a central observer; that sounds as if it has a tinge of allocentrism about it. I accept that a clear distinction can be drawn in practice between the ability to make allocentric and egocentric judgements, but that difference doesn’t have to be reflected all the way down to the level of the coding schemes involved.

Briscoe goes on to offer a few concluding remarks which perhaps reveal something of his underlying motivation: in essence, he wants to preserve a strong connection between conscious perception and agency. I sympathise with this, even with the strong claim that we need at least a potential for agency before we can have perception. But I remain to be convinced that egocentric coding of conscious visual experience is indispensable to the cause.

Picture: Pinocchio. You may have seen that Edge, following its annual custom, posed an evocative question to a selection of intellectuals to mark the new year. This time the question was ‘What have you changed your mind about? Why?’. This attracted a number of responses setting out revised attitudes to artificial consciousness (not all of them revised in the same direction). Roger Schank, notably, now thinks that ‘machines as smart as we are’ are much further off than he once believed, though he thinks Specialised Intelligences – machines with a narrow area of high competence but not much in the way of generalised human-style thinking skill – are probably achievable in the shorter term.

One remark he makes which I found thought-provoking is about expert systems, the approach which enjoyed such a vogue for a while, but ultimately did not deliver as expected. The idea was to elicit the rules which expert humans applied to a particular topic, embody them in a suitable algorithm, and arrive at a machine which understood the subject in question as well as the human expert, but didn’t need years of training and never made mistakes (and incidentally, didn’t need a salary and time off, as those who tried to exploit the idea for real-world business applications noted). Schank contrasts expert systems with human beings: the more rules the system learned, he says, the longer it typically took to reach a decision; but the more humans learn about a topic, the quicker they get.

Now there are various ways we could explain this difference, but I think Schank is right to see it as a symptom of an underlying issue, namely that human experts don’t really think about problems by applying a set of rules (except when they do, self-consciously): they do something else which we haven’t quite got to the bottom of. This is obviously a problem – as Schank says, how can we imitate what humans are doing when humans don’t know what they are doing when they do it?

Another Edge respondent expressing a more cautious view about the road to true AI is none other than Rodney Brooks. Noting that the preferred metaphor for the brain has always tended to be the most advanced technology of the day – steam engines, telephone exchanges, and now inevitably computers – he expresses doubt about whether computation is everything we have been tempted to believe it might be. Perhaps it isn’t, after all, the ultimate metaphor.

It seems to me that in different ways Schank and Brooks have identified the same underlying problem. There’s some important element of the way the brain works that just doesn’t seem to be computational. But why the hell not? Roger Penrose and others have presented arguments for the non-computability of consciousness, but the problem I always have in this connection is getting an intuitive grasp of what exactly the obstacle to programming consciousness could be. We know, of course, that there are plenty of non-computable problems, but somehow that doesn’t seem to touch our sense that we can ultimately program a computer to do practically anything we like: they’re not universal machines for nothing.

One of John Searle’s popular debating points is that you don’t get wet from a computer simulation of rain. Actually, I’m not sure how far that’s true: if the computer simulation of a tropical shower is controlling the sprinkler system in a greenhouse at Kew Gardens, you might need your umbrella after all. Many of the things AI tries to model, moreover, are not big physical events like rain, but things that can well be accomplished by text or robot output. However, there’s something in the idea that computer programs simulate rather than instantiate mental processes. Intuitively, I think this is because the patterns of causality are necessarily different when a program is involved: I’ve never succeeded in reducing this idea to a rigorous position, but the gist is that in a computer the ‘mental states’ being modelled don’t really cause each other directly; they’re simply the puppets of a script which is really operating elsewhere.

Why should that matter? You could argue that human mental states operate according to a program which is simply implicit in the structure of the brain, rather than being kept separately in some neural register somewhere; but even if we accept that there is a difference, why is it a difference that makes a difference?

I can’t say for sure, but I suspect it has to do with intentionality, meaningfulness. Meaning is one of those things computers can’t really handle, which is why computer translations remain rather poor: to translate properly you have to understand what the text means, not just apply a look-up table of vocabulary. It could be that in order to mean something, your mental states have to be part of an appropriate pattern of causality, which operating according to a script or program will automatically mess up. I would guess further that it has to do with a primitive form of indexicality or pointing which lies at the foundation of intentionality: if your actions aren’t in a direct causal line with your behaviour, you don’t really intend them, and if your perceptions aren’t in a direct causal line with sensory experience, you don’t really feel them. At the moment, I don’t think anyone quite knows what the answer is.

If that general line of thought is correct, of course, it would be the case that we cannot ever program or build a conscious entity – but we should be able to create circumstances in which consciousness arises or evolves. This would be a blow for Asimovians, since there would be no way of building laws into the minds of future robots: they would be as free and gratuitous as we are, and equally prone to corruption and crime. On the other hand, they would also share our capacity for reform and improvement; our ability, sometimes, to transcend ourselves and turn out better than any programmer could have foreseen – to start something good and unexpected.

Belatedly, Happy New Year!

Picture: reincarnated entity.

Picture: Blandula. Jonathan Edelmann and William Bernet have made a sterling effort to bring reincarnation within the pale of scientific investigation. Their paper, in the latest JCS, is not directly concerned with the reality of reincarnation, but with the methods which could be adopted to ensure the academic credibility of future research.

They put to one side cases where the recollection of a previous life is induced by hypnosis, because of the obvious difficulties in ensuring that the subject is not led or influenced by the hypnotist, and concentrate instead on ‘spontaneous’ cases – those where a child comes up with memories of a former life without any particular prompting.

I say ‘without any particular prompting’, but the authors recognise that many alleged cases of reincarnation occur within cultures where a belief in the phenomenon is a religious obligation, and where family members are likely to prompt and encourage any signs of recollection displayed by a child. Indeed, one of their main concerns is to establish interview procedures which will eliminate direct family influence, provide an objective assessment, and include a comparison of the household described in the child’s recollections with a control household.

Picture: Bitbucket. I salute their aspiration to scientific rigour, but their efforts are tragically misplaced. Scientific investigation is wasted if the hypothesis under investigation is incoherent, and I think the notion of reincarnation is pretty much unsalvageable. It rests on a confused conception of identity, and once your ideas about identity are clarified – in any rational way – it becomes absurd. To put the problem at its most general: proponents of reincarnation accept any resemblance between dead and live persons as evidence for reincarnation- it can be personality, memories, tastes, abilities, or even physical characteristics. But if all properties are equally signs of identity, the missing resemblances are as salient as the present ones. If a gift for juggling is claimed as a sign of identity between dead A and live B in one case, I’m entitled to point out that dead X and live Y differ in their juggling abilities, though allegedly Y remembers X’s life. But this is never allowed; only the points of resemblance are ever considered. Frankly, it’s superstition.

Picture: Blandula. I don’t think that’s right. The best evidence for reincarnation isn’t from resemblances of that kind, but the recollection of factual information about previous lives. The ability to produce detailed memories of a former existence is so remarkable that even a few instances constitute striking evidence. The fact that some other details are not recalled does not cancel that evidence out. If I could describe my car and tell you its registration number, that would be good evidence that I really had at least seen it before: the fact that I couldn’t tell you what was inside it or what brand name was on the battery wouldn’t disprove that.

Edelmann and Bernet do seem to countenance a range of different evidence in principle, though: they begin by quoting the four-point SOC (Strength of Case) scale developed at Virginia University. The four points are, briefly:

  • birthmarks/defects that correspond to the previous life;
  • strength of statements about the previous life;
  • relevant behaviours that relate to the previous life; and
  • possible connections between present and previous life

Picture: Bitbucket. See what I mean? Look at that first point. Birthmarks and defects? Look, reincarnation is supposed to be the transfer of a soul into another body, not the transfer of a body into a body. If birthmarks and defects are transferred, why not the disease that killed the original person? Why not the signs of old age? If physical traits are transferred, why don’t babies get reincarnated as old people? In fact, why don’t they come back as corpses?

Picture: Blandula. You’re the last person who should be surprised that mental traits can have a physical expression. I’m not asserting that birthmarks are signs of reincarnation, but if you believe in souls, there’s nothing contradictory in supposing that certain physical characteristics impress themselves on the spirit in a way that others don’t. and that these impressed characteristics can then be echoed in the body when the spirit arrives in a new corporeal host.

Anyway, let me finish the exposition before you start arguing – as I explained, we’re addressing methodological issues here rather than the reality of reincarnation in itself.

Edelmann and Bernet propose four phases of research. In the first, the child is questioned about its earlier life in a videotaped interview conducted by professionals, who seek to draw out clear, specific and verifiable information. A second group of researchers evaluates the data gathered in phase 1, checking on the child’s life and circumstances to eliminate the possibility of their having acquired information about a previous life by normal means. In this respect, the authors note that the best subjects are likely to be young children, since they are least likely to have been able to research earlier lives or pick up data by normal means of communication. The second group of researchers go on to draw up a list of 20 ‘descriptors’ – items about the supposed previous life drawn from the interviews with the child. They also identify the site of the earlier life and another superficially like it. They might, for example, find the house where the child claims to have lived, and then pick a house with the same number in a different street.

On to phase 3. A further group of researchers is now given the two addresses (without being told which is which) and the list of descriptors: they then score both sites according to how many of the descriptors apply. In the final phase, the whole exercise is re-examined for flaws or mistakes, and the results evaluated statistically.

Sadly, no research along these lines has taken place, but it seems to hold out the possibility of opening up reincarnation for proper scientific research.


Picture: Bitbucket. The trouble is, the research is still going to be tainted, isn’t it? We’re dealing with cultures where reincarnation is accepted; how can they ever eliminate the possibility that Mum and Dad have hit on the idea that Junior is the reincarnation of Great-Uncle Jasper, and told him all sorts of stuff they know about the old man and his life? It seems hopeless to me. Maybe it would work if they could show that Junior was able to remember Uncle Jasper’s bank account password, or something else that no-one else would have known.

But it’s hopeless on a deeper level. What are the criteria for personal identity? Nobody really has an uncontroversial answer, so how can we begin making claims that a particular live person is identical with a certain dead one?

After all, I am not exactly the same as I was a year ago, let alone as I was when I was five: some people would say that my claim to be identical with that five year old is really only a kind of polite or convenient fiction. I wouldn’t go that far: it seems to me that biological continuity is a pretty good indicator of identity. I’d be inclined to make death and birth the ending and beginning of new individuals more or less by definition – so even if you are just like Uncle Jasper, and even share some of his memories, that doesn’t mean you are him.

Picture: Blandula. I accept that there are issues about identity. It might be that reincarnation doesn’t turn out to be what we think it is. Edelmann and Bernet suggest that if reincarnation really happens, we must transform our view of the ontology of consciousness, rule out reductive materialism, and look again at non-physical views. I think they’re only partly right: it seems perfectly feasible to me to come up with a version of reincarnation which is compatible with materialism. Just to take an easy example: suppose consciousness really is a kind of electromagnetic buzz, as people like Pockett and McFadden have supposed. It seems prima facie possible that this buzz could get echoed or stored in some way and have an effect on the emergent buzz of an infant, transferring memories and personality traits – perhaps even some physical ones.

The way I see it, the first step is to establish the reality or otherwise of the transfer of memory – metemmnemonism? – along the lines Edelmann and Bernet have suggested. Then we can have the discussion about whether ‘metemmnemonism’ implies metempsychosis.


Picture: Bitbucket. Gotta love your idea of rigorous scientific materialism there – no souls, just ‘buzzes’.

I’d be happy with the idea of this research if I didn’t know how it would go. Suppose the research takes place and finds no reliable evidence of reincarnation. Will the researchers then conclude the thing is disproved, case closed? No: they’ll say they failed to find evidence, but someone should have another go. Negative results will not be counted, but when some idiot messes up the procedures and gets an invalid positive result, it’ll be acclaimed and enter the mythology as cast-iron proof. That’s paranormal research for you – we may not get reincarnated, but the discredited theories always come back from the dead.