There’s a lovely story by our science correspondent Nick Collins today in our paper about how our brain can filter out background noise, rather like those noise-reducing headphones, in order to concentrate on the person speaking; he calls it the "cocktail party problem". The jumble of sound waves enters our ear, and passes through the auditory cortex in that same jumble – clinking glasses and coughs all mixed in together with the words of the speaker – but as it goes through the parts of the brain that manage language and attention, the sounds that make up that speech are singled out and "amplified" while the unimportant stuff is relegated to the background.
It's fascinating, but it's very much part of the wider picture of our brains as a series of interlinked subroutines and modules, each with highly specific tasks. For example, an equivalent is our ability to recognise faces: they leap out of the surroundings, a little automatic routine in our brain constantly on the search for the shape of eye-eye-nose-mouth; it's why we see faces in clouds, JFK's profile in rocks. This highly specific skill, which includes the ability to mentally age faces so that we can recognise an old man from a photo of him as a teenager, is managed by an equivalently specific area: the fusiform gyrus, at the bottom of each hemisphere of the brain. People with damage to this area are just as visually capable as everyone else in every other aspect – they can recognise, say, objects – but can't recognise people's faces: the condition is known as "prosopagnosia".
The idea that we have a specific module for recognising faces might not be all that surprising. But how about the mooted idea that there is something in our brains which is designed to recognise “tools”, as opposed to just objects? Another one that has the job of recognising fruits and vegetables? Different kinds of brain damage can knock out, or at least impair, these different skills. Dr P, a sufferer of object-blindness described in Oliver Sacks’s wonderful book The Man Who Mistook His Wife For A Hat, could recognise cubes, spheres, dodecahedrons with ease; could recognise jacks, kings and queens in cards; but when asked what the object in front of him was, said hesitatingly “A continuous surface, infolded on itself. It appears to have five outpouchings, if this is the word.” The object was a glove.
It goes on. Language and reading isn’t just one part, it’s several; people who suffer from expressive aphasia, caused by damage to a part of the brain called Broca’s area, leaves them capable of understanding speech, of reading and writing – but unable speak in complete sentences themselves, rarely able to put more than four words together in a row. There are dozens of these sort of things, often very strange indeed.
The implication is that the brain – consciousness – is made of hundreds, or thousands, of smaller parts. Which of course it is. As Daniel Dennett says in Consciousness Explained, we are made of around 100 trillion tiny robots, cells. Not one of them is conscious; not one of them “knows who you are, or cares”, as he puts it in a lecture on the subject (see video above). Yet somehow, out of those unconscious parts, consciousness is made. Or so materialists like me believe, anyway.
But, of course, “the ability to recognise tools” isn’t “consciousness”; the ability to speak, the ability to see and divide the universe into objects and people and animals, to recognise patterns – all these things that we can isolate and perhaps one day explain – are not “consciousness”. Some people, including the philosopher David Chalmers, call this is the “hard problem” of consciousness: you can explain all the subroutines, you can explain all the bits and bobs and tools and functions, but you can’t explain “me”, why I, this unified self, this feeling subject, experiences the world as I do.
This is one of the great arguments of philosophy and neuroscience, and I don’t pretend to be able to tell David Chalmers that he’s wrong and that Daniel Dennett is right. But I prefer Dennett’s argument, which approaches the problem of consciousness with practicality rather than mysticism. He compares consciousness to a magic trick, called The Tuned Deck. It’s a pretty ordinary pick-a-card-any-card routine, but Ralph Hull, the 1930s magician who invented it, puzzled all of his contemporaries for years with it, who simply could not explain it. Dennett says:
Like much great magic, the trick is over before you even realize the trick has begun. The trick, in its entirety, is in the name of the trick, “The Tuned Deck”, and more specifically, in one word, “The”. As soon as Hull had announced his new trick and given its name to his eager audience, the trick was over… Hull would do a relatively simple and familiar card presentation trick of type A.His audience, savvy magicians, would see that he might possibly be performing a type A trick, a hypothesis they could test by being stubborn and uncooperative spectators in a way that would thwart any attempt at a type A trick. When they then adopted the appropriate recalcitrance to test the hypothesis, Hull would ‘repeat’ the trick, this time executing a type B card presentation trick. The spectators would then huddle and compare notes: might he be doing a type B trick? They test that hypothesis by adopting the recalcitrance appropriate to preventing a type B trick and still he does “the” trick – using method C, of course. When they test the hypothesis that he’s pulling a type C trick on them, he switches to method D – or perhaps he goes back to method A or B, since his audience has ‘refuted’ the hypothesis that he’s using method A or B.
The same thing is going on with consciousness, he says. If you explain a “trick” – whether it’s pattern recognition or language or self-consciousness or proprioception or any of hundreds of other parts of the mind that we can take some steps to explaining – then you’ve just explained a trick, you haven’t explained consciousness. So you explain another one. But you haven’t explained consciousness, you’ve just explained another trick the brain can do.
But “consciousness” isn’t one big magic thing, it’s thousands of little parts, says Dennett. By giving it this one big name, we trick ourselves, like we do with “The Tuned Deck”, into thinking there is only one big thing to explain, the subject, the I, the ego. But there isn’t. There are hundreds, or thousands, or millions, depending on how big a bit you’re looking at: our cleverness, our consciousness, is made of thousands of stupid robots. Explaining consciousness involves explaining the smaller bits, and then explaining how those bits are made of still smaller bits, and still smaller bits, until you’re down to the cells.
Of course, some people want consciousness, the self, the soul, to be mysterious, and that’s fine. But if, like me, you prefer the idea that we can take it apart and see how it fits together, then things like the “cocktail party problem” show us how it could be done.
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