Archive for November, 2007

Picture: smiling computer. We’ve discussed here previously the enigma of what grief is for; but almost equally puzzling is the function of laughter. Apparently laughter is not unique to human beings, although in chimps and other animals the physical symptoms of hilarity do not necessarily resemble the human ones very closely. Without going overboard on evolutionary explanation, it does seem that such a noteworthy piece of behaviour must have some survival value, but it’s not easy to see what a series of involuntary and convulsive vocalisations, possibly accompanied by watering eyes and general incapacitation, is doing for us. Shared laughter undoubtedly helps build social solidarity and good feeling, but surely a bit of a hug would be fine for that purpose – what’s with the cachinnation?

Igor M. Suslov has a paper out, building on earlier thoughts, which presents an attempt to explain humour and its function. He thinks it would be feasible for a computer to appreciate jokes in the same way as human beings; but the implication of his theory seems to be that a sophisticated computer – certainly one designed to do the kind of thinking humans do – would actually have to laugh.

Suslov’s theory draws on the idea (not a new one) that humour arises from the sudden perception of incongruity and the resulting rapid shift of interpretation. When cognitive processes attain a certain level of sophistication, the brain is faced with many circumstances where there are competing interpretations of its sensory input. Is that a bear over there, or just a bush? The brain has to plump for one reading – it can’t delay presenting a view to consciousness until further observations have resolved the ambiguity for obvious practical reasons – and it constructs its expectations about the future flow of events on that basis: but it has the capacity to retain one or two competing interpretations in the background just in case. In fact, according to Suslov, it holds a number of branching future possibilities in mind at any one time.

The brain’s choice of scenario can only be based on an assessment of probability, so it is inevitably wrong on occasion -  hey, it’s not a bear, after all! In principle, the brain could wait for the currently assumed scenario to drain away naturally when it reached its current end: but the disadvantages of realising one’s error slowly are obvious. Theoretically another alternative would be to delete all recollection of the original mistake: but the best approach seems to be to tolerate the fact that our beliefs about the bush conflict with what we remember believing. The sudden deletion of the original interpretation is the source of the humorous effect.

Suslov has drawn on the views of Spencer, which had it that actual physical laughter was caused by the discharge of nervous energy from mental process into the muscles. This theory, once popular, suffered the defect that there really is no such thing as ‘nervous energy’ which behaves in this pseudo-hydraulic style; but Suslov thinks it can be at least partially resurrected if we think of the process as excess energy arising from the clearance of large sections of a neural network (when a scenario is deleted). He recognises that this is still not really an accurate biological description of the way neurons work, but he evidently still thinks there’s an underlying truth in it.

One further point is necessary to the plausibility of the theory, namely that humour can be driven out by other factors. We may laugh when we realise the ‘bear’ is really a bush, but not when we make the reverse discovery. This is because the ‘nervous energy’, if we can continue to use that term, is directed into other emotions, and hence goes on to power shaking with fear rather than laughter. Suslov goes on to explain a number of other features of humour in terms of his theory with a fair degree of success.

An interesting consequence if all this were true, it seems to me, is that a network-based simulation of human consciousness would also necessarily be subject to sudden discharges. It seems to me this could go two ways. Either the successful engineers are going to notice this curious and possibly damaging property of their networks, or at some stage they are going to encounter problems (the frame problem?) which can in the end only be solved by building in a special rapid-delete facility with a special provision for the tolerance of inconsistency. Use of this facility would amount to the machine laughing.

Would it, though? There would be no need, from an engineering point of view, to build in any sound effects or ‘heave with laughter’ motors. Would the machine enjoy laughing, and seek out reasons to laugh? There seems no reason to think so, and it is a definite weakness of the theory that it doesn’t really explain why humour is anything other than a neutral-to-unpleasant kind of involuntary shudder. Suslov more or less dismisses the pleasurable element in humour: it’s more or less a matter of chance, he suggests, just as sneezing happens to be pleasant without that being the point of it. It’s true that humans are good at taking pleasure in things that don’t seem fun at first sight; making the capsaicin which is designed to deter animals from eating peppers into the very thing that makes them taste good, for example. But it’s hard to accept that funny things are only pleasant by chance; it seems an essential feature of humour is being left on one side.

It’s also possible to doubt whether all humour is a matter of conflicting interpretations. It’s true that jokes typically work by suddenly presenting a reinterpretation of what has gone before. Suslov claims that tickling works in a similar way – our expectations about where the sensation is coming from next are constantly falsified. Are we also prepared to say that the sight of someone slipping on a banana skin is funny because it upsets our expectations? That might be part of it: but if conflicting interpretations are the essence of humour, optically ambiguous figures like the Necker cube should be amusing and binocular rivalry ought to be hilarious.
There are of course plenty of technical issues too, apart from the inherent doubtfulness of whether the metaphor of ‘nervous energy’ can really be given a definite neurological meaning.

One aspect of Suslov’s ideas ought to be testable. It’s a requirement of the theory that the discarded interpretation is deleted, otherwise there is no surplus ‘nervous energy’. But why shouldn’t it simply recede to the status of alternative hypothesis? That seems a more natural outcome. If that were what happened, we should be ready to change our minds back as quickly as we changed them the first time: if Suslov is right and the discarded reading is actually deleted, we should find it difficult to switch back to the ‘bear’ hypothesis once we’ve displaced it with the ‘bush’ reading. That ought to show up in a greater amount of time needed for the second change of mind. I doubt whether experiments would find that this extra delay actually occurs.

Picture: Bonobo. This piece by Clive Wynne reviews the well-known attempts which have been made to teach chimps (or bonobos) to use language, and draws the melancholy conclusion that the net result has in the end merely confirmed that grammar is uniquely human. It seems a fair assessment to me (though I always find it difficult not to be convinced by some of the remarkable videos which have been produced) , but it did provoke some thoughts that had never occurred to me in this connection before.

According to Wynne, the chimps show clear signs of recognising a number of nouns, but no sign of either putting the nouns in the right order, or recognising the significance of the order in which they have been put by humans. They cannot, in other words, distinguish between ‘snake bites dog’ and ‘dog bites snake’, which is a key test of grammatical competence.

But word order is obviously not the whole story so far as grammar is concerned. One of the first things you learn in Latin is that in that language, although there may be a preferred word order, it isn’t grammatically decisive: ‘Serpens mordet canem’ means the same as ‘Canem mordet serpens’ (to express the reversed relationship, you’d have to say ‘Canis mordet serpentem’). Perhaps apes just have trouble with grammars like that of English which rely on word order; perhaps they would do better with a language which used inflection, or some other grammatical mechanism instead? Was failure, in short, built into these experiments just as surely as it was into the doomed earlier attempts to teach them to speak?

Two quite different languages were involved in the different experiments: Washoe and other chimps were taught ASL, a sign language used by deaf humans; Kanzi and others were taught to communicate in specially-created lexigrams, symbols arranged on a keyboard, though the experimenters apparently used spoken English for the most part.

I don’t know much about ASL, but it does appear to use word order, albeit a different one from that in normal English; typically the topic is mentioned first, followed a comment. You can do this sort of thing in English of course (‘That snake – the dog bit it.’), but it isn’t standard. If you want to specify a time in ASL, which might be done with tenses in English, you should mention it first, before the topic. In making your comment, the word order appears to be similar to the standard English one, though there may be some degree of flexibility. My impression is that ASL users would tend to break down the information they’re conveying into smaller chunks than would be normal in English, taking a clause at a time to help minimise ambiguity. There is something called inflection in ASL, but it isn’t the kind of conjugation and declension we’re used to in Latin, and doesn’t play the same grammatical role. In fact, one important grammatical indicator in ASL is facial expression – a possible problem for the chimps, although they could presumably manage some of the basic head-tilting and eye-brow (alright, brow-ridge) raising.

With lexigrams. the relationship to standard English is closer: each of the 384 lexigrams is equivalent to an English word, and indeed some consist of the word written in a particular shape with particular colours. This obviously makes things easy for the experimenters and in some ways for the bonobos, who would otherwise be faced with learning two languages, heard English and spoken lexigram. The grammar involved is therefore essentially English, and if anything the use of lexigrams makes word order even more crucial, since verbs are necessarily invariant and there are no plurals: so we don’t even get the kind of extra clues we might have in an English sentence like ‘The dog bites the snakes’.

Prima facie then, it does seem to me that unless the chimps were naturally at ease with using English-style word order as their sole grammatical tool, they were actually given little scope to demonstrate grammatical abilities by any of these experiments. We can perhaps follow the implications a little further. ASL is not very much like ordinary English in its grammar or structure. The adoption of a different channel of communication by deaf people appears to have called for a very different language. It seems natural to suppose, then, that if we require even more radically different channels to communicate with chimps we need a language even more remote from English. Perhaps both ASL and lexigrams are too strongly adapted for human use: true communication may require a form of language which is novel and as difficult for human beings to learn as the chimps; one in fact which might require some rethinking of how grammar can be expressed (something similar had to happen before it was accepted that ASL and other sign languages had true grammar). But if merely understanding this hypothetical language would be dauntingly difficult for us, it hardly seems probable that we could construct it in the first place.

The only way such a language could be constructed, I think, is if the chimps were able to make an equal contribution from their side, rather than being captives drilled in an essentially human style of communication. If a human and chimp community enjoyed a close but free relationship of real importance to both, possibly based on trade or similar relations of mutual benefit, perhaps the differing conventions of different species could be shared and a kind of pidgin developed, as happened all over the world when Western traders first appeared – although this time it would have to be a non-vocal one. The chances of anything like this happening, if not zero in any case are of course remote, and growing less all the time, so sadly the chances are that if chimps do after all have some grammatical ability, we’ll never really know about it.

Picture: Binocular rivalry. The idea that quantum mechanics is part of the explanation of consciousness, in one way or another, is supported by more than one school of thought, some of which have been covered here in the past. Recently MLU was quick to pick up on a new development in the shape of a paper by Efstratios Manousakis which claims that testable predictions based on the application of quantum theory have been borne out by experiment.

The claims made are relatively modest compared to those of Penrose and Hameroff, say. Manousakis is not attempting to explain the fundamental nature of conscious thought, and the quantum theory he invokes isn’t new. At its baldest, his paper merely suggests that dominance duration of states in binocular rivalry can be accurately modelled by assuming we’re dealing with a small quantum mechanical system embedded in a classical brain – although if that much were true, it would certainly raise further issues.

But let’s take it one step at a time. What is binocular rivalry, to begin with? When radically different images are presented to the left and right eye, instead of a blurry mixture of both images, we generally see one fairly clearly (occasionally a composite made of bits of both images); but curiously enough, the perceived image tends to switch from one to the other at apparently random intervals. Although this switching process can be influenced consciously, it happens spontaneously and therefore seems to be a kind of indecisiveness in some unconscious mechanism in our visual system.

Manousakis proposes a state of potential consciousness, with the two possible perceptions hanging in limbo. When the relevant wave function is collapsed through the intervention of another, purely classical brain mechanism, one or other of the appropriate neural correlates of consciousness is actualised and the view through one eye or the other enters actual consciousness. This model clearly requires perception to operate on two levels; one, a system that generates the potential consciousness, and two, another which actualises states of consciousness by checking up every now and then.

Thus far we have no particular reason to believe that the application of quantum concepts is anything more than a rather recondite speculation; but Manousakis has shown that the persistence of one state in the binocular rivalry, and the frequency of switching, can be predicted on the basis of his model: moreover, it explains and accurately predicts another observed phenomenon, namely that if the stimuli in a binocular rivalry experiment are removed and returned at intervals, the frequency of switching is significantly reduced. If I’ve understood it correctly (and I’m not quite sure I have), one of the two images tends to stay around because when you collapse the wave function a second time, there is a high probability of it collapsing the same way. If you remove the images for a while, no new collapses can occur until the images return. It’s as though you were throwing a dice and moving to the other state when you threw a six; if you keep throwing, the changes will happen often, but if you take the dice away for a few minutes between each throw, the changes will become less frequent.

Manousakis has also demonstrated that his theory is consistent with the changes observed in subjects who had taken LSD (a slightly puzzling choice of experiment – I’m slightly surprised it’s even legal – but it seems it reflects established earlier findings in the field).

So – a breakthrough? Possibly, but I see some issues which need clearing up. First, to nail the case down, we need better reasons to think that no mere classical explanation could account for the observations. There might yet be easier ways to account for changes in dominance duration. We also need some explanation of why quantum mechanics only seem to apply in unusual cases of ambiguity like binocular rivalry. A traditional theorist who attributes binocular rivalry to problems with the brain’s interpretative systems has no trouble explaining why the odder effects only occur when we impose special interpretive challenges by setting up unusual conditions: but if a quantum mechanical system is doing the job Manousakis proposes, I would have thought occasional quantum jumps would have been noticeable in ordinary perception, too.

It would help, in addition, to have a clearer idea of how and why quantum mechanics is supposed to apply here. It could presumably be that potential consciousness is generated at a microscopic level where quantum effects would naturally be observable: an account of how that works would be helpful – are we back with Penrosian microtubules? However, Manousakis seems to leave open the possibility that we’re merely dealing with an analogy here, and that the maths he employs just happens to work for both good old-fashioned quantum effects and for a subtle mental mechanism whose basic nature is classical. That would be interesting in a different way.

It will be interesting, in any case, to see whether anyone else picks up on these results.