杏吧原创

FOR all the millions of words generated in the quest to explain consciousness, are we really any nearer understanding it? Will the field ever boast its own theory of everything, one good enough to explain how non-material experience can miraculously appear in material brains?

Philosophers, psychologists, researchers of all flavours, have been striving to produce something definitive. You can hardly blame them for trying, but the main consensus so far is that consciousness is probably the trickiest thing we know of to pin down. It has no obvious function 鈥� as the mere fact of the many competing theories attests, together with the surprisingly popular view in some circles that it may be 鈥渆piphenomenal鈥� (a way of saying 鈥渄oes nothing鈥�).

Worse, running the sort of super-heated consciousness humans possess is almost certainly costly in energy terms, thus raising questions about how it could possibly have evolved. Yet at the same time it is a compelling area, as attractive as frontier physics.

But what do all these theories amount to? Not much according to some, who attack consciousness studies on the grounds that we are asking the wrong questions, or who claim that we are about as capable of understanding consciousness as is a dog of comprehending quantum theory.

That鈥檚 the background against which this slim little book is set. Its author is the multi-talented Nicholas Humphrey, based at the London School of Economics. He鈥檚 a primatologist/psychologist/philosopher, who may have been the first to arrive at a totally bizarre phenomenon called 鈥渂lindsight鈥� (the ability to perceive things visually in the absence of conscious awareness of that perception). His theories draw on his fields of expertise, as well as weaving in the findings and ideas of other researchers. Amazingly, he achieves this in a book a quarter the size of most competitors. And it鈥檚 a delight to read, beautifully clear and concise, while packing lots of good sense.

The starting point for his intellectual tour de force is a 1989 quote from British psychologist Stuart Sutherland鈥檚 influential Dictionary of Psychology: 鈥淐onsciousness is a fascinating but elusive phenomenon; it is impossible to specify what it is, what it does, or why it evolved. Nothing worth reading has ever been written about it.鈥�

Interestingly, notes Humphrey, nearly two decades on, a quick trawl of the web shows 48 sites still citing this discouraging definition 鈥渨ith approval鈥�. His trick, however, is to turn the tables on Sutherland by suggesting that fascination and elusiveness is the whole point of consciousness. It has to be like that, he says, because it evolved to give its possessors the sense of owning a 鈥渟elf worth having鈥�. This is no small gift. Just about everything we call human depends on it: culture, richness of our subjective lives, friendship, imagination, spirituality, caring 鈥� the list is endless.

鈥淔ascination and elusiveness is the whole point of consciousness鈥�

Written in the style of a lecture, Humphrey centres his book round a reader-friendly example, the experience of 鈥渟eeing red鈥� (as in paint or tomatoes). When we look at a red screen, we鈥檙e doing something Humphrey describes as 鈥渢ruly remarkable鈥�: we鈥檙e generating a particular state of consciousness and 鈥渉aving a red sensation鈥�. This first-person response to light with a wavelength of around 760 nanometres is a complex, very active process, which Humphrey dubs 鈥渞edding鈥�. It can be divided into components, three of which are: having a perception of red, which involves the brain responding to the colour; feeling this perception is happening; and getting the sensation that the screen is red. (There鈥檚 another 鈥渒iller鈥� component, but more later.)

Humphrey amasses powerful evidence to show that sensation is what really counts here. It involves a lot more than just perception of information about light wavelength or whatever. For example, from humans to pigeons, animals respond emotionally to colour in similar ways: red is strong, hot, 鈥渇ast鈥�, disturbing, while blue is cool, calm, 鈥渟lower鈥�. Then there鈥檚 Humphrey鈥檚 work on blindsight, an interest dating back to an early job when he made friends with a lab monkey. Humans with blindsight have no sensation of seeing when they are quizzed. They generally report they were 鈥渏ust guessing鈥� when they get it right.

But why should such a strange divorce between perception and conscious sensation exist 鈥� one that seems to leave consciousness a latecomer or bystander with no obvious function? For Humphrey, the answer lies in evolutionary theory. By the by, his brand of evolutionary psychology escapes the criticism that this field amounts to little more than a collection of 鈥淛ust So鈥� stories, conjuring contentious explanations for modern human behaviour out of armchair theorising. Humphrey鈥檚 story is based on much broader principles than the academic notions about what life 鈥渕ust鈥� have been like for hunter-gatherers that bedevil much of the field.

So, for primitive creatures at an early stage of evolution, the surface of their bodies separated self from environment. For them, interactions with the environment involved nothing more than automatic, reflex responses. Factor in time and increasing complexity, and the creatures did better (survived longer, bred more) by developing systems able to keep track of these reactions. They could, for instance, ascertain which responses had better or worse outcomes, and learn to avoid the latter. Over time, such tracking systems became more divorced from stimulus-response systems, allowing them to do other useful things such as rehearsing potential responses without having to act them out. The tracking system became more 鈥減rivatised鈥�, and the 鈥渟elf鈥� internalised.

Enter the 鈥渒iller鈥� component of the 鈥渟eeing red鈥� experience. A new selective advantage kicked in for these privatised, proto-conscious systems: they developed into self-important 鈥渟elves鈥�. For the first time, organisms could treat themselves as special, requiring cossetting, forethought in the interests of their own welfare, and so on. They needed awareness, especially of themselves, to seem special and mysterious because it motivated them to put extra effort into their survival. In short, they mattered to themselves.

Now this is a thoroughly appealing and plausible notion. It does not tell us 鈥渉ow鈥� the special quality of consciousness arises, but does explain 鈥渨hy鈥� experience should seem so special. It accounts for both the puzzling separation between perception and sensation, and why evolution favoured our form of experience. Moreover, it is consistent with a range of neuroscientific approaches to the 鈥渉ow鈥� question. Few contemporary writings on consciousness achieve half as much.

Does it have implications for how we think about ourselves? Humphrey concludes that, because consciousness developed to fulfil the evolutionary purpose he describes, it should probably be regarded as nothing more than a lovely illusion. His is a reductionist interpretation, reminiscent of those of Richard Dawkins or Daniel Dennett. But that鈥檚 a bit like saying that, because an author writes to make a living, his books have no real value except as money-spinners. Clearly they have other values 鈥� for example, the quest for truth in this book. Similarly, even if consciousness evolved because it provided a sense that individuals matter, it could still be the case that they do matter in some non-illusory sense. Maybe their mattering was a truth that provided the basis for evolution to work on. Your guess is as good as mine 鈥� or Humphrey鈥檚.