The Divided Brain and the Search for Meaning

by Iain McGilchrist

Our increasing ability to manipulate the world does indeed appear somehow connected with its loss of meaning for us. Why? And does it even matter?

The two hemispheres are different sizes, shapes, and weights (the right hemisphere is bigger and heavier in all social mammals); have different gyral conformations on the surface, and in places different cytoarchitecture – that is to say the arrangement of the cells; different proportions of grey matter to white, different sensitivity to neuroendocrine influences, and rely on different preponderances of neurotransmitters.

I think it can be attributed to adopting the wrong model in our attempts to understand what we were looking at. We can only ever understand anything by comparing it with something else that we think we already understand better.

All understanding is in this sense provisional, a matter of observing similarities and differences with something we already think we know. We had modelled the brain as part of a machine, the hemispheres as mechanical parts of a mechanical body. There are, of course, only two possible models: seeing it as part of a machine or as part of a person. So we had a 50 per cent chance of getting it right. But we managed to make the wrong choice.

we can only know the world as we have inevitably shaped it by the nature of our attention.

I take it that we bring about a world in consciousness that is partly what is given, and partly what we bring, something that comes into being through this particular conjunction and no other. And the key to this is the kind of attention we pay to the world.

What we do not expect to find, we just will not see: much elegant research demonstrates that we are essentially blind to what we do not think is there.

The right hemisphere underwrites sustained attention and vigilance for whatever may be, without preconception. Its attention is not in the service of manipulation, but in the service of connection, exploration and relation.

One way of looking at the difference would be to say that while the left hemisphere's raison d'être is to narrow things down to a certainty, the right hemisphere's is to open them up into possibility.

It is not possible to know the values of all of the properties of the system at the same time. Mechanical systems, even at their simplest, are likely to produce highly complex outcomes. Not infrequently their behaviour is intrinsically unpredictable and unknowable (the simple double pendulum – one pendulum attached to the bottom of another – is a classical example of ‘chaotic dynamics').

description can you be said to have seen something clearly? Is a book seen clearly when it is seen as a whole in your hand, or when you read it, or when you take a magnifying glass to the paper and see the hills and dales of the paper, or when you go further and see the filamentous threads of which the paper is composed, or under electron microscopy, or when it finally resolves into probabilities of the presence of subatomic particles, and reveals itself to be mostly – nothing at all?

is metaphors that carry us across (that is what the word ‘metaphor’ means) the implied gap between language and the world, and make what would otherwise be a hermetically sealed system of signs capable of meaning something in terms of embodied experience.

Explicitness kills, renders lifeless. An act of sexual love, or an act of worship, reveal little of their true selves in the lab, seen through an observation window. But neither would a football match, a meal with friends, or a comedy show.

Another way of thinking of the difference between the hemispheres is to see the left hemisphere's world as tending towards fixity, whereas that of the right tends towards flow.

Only the left hemisphere encodes tools and machines – you will remember that the purpose of the left hemisphere is to allow us to manipulate the world, not to understand it.

In the past we would naturally model the world according to organic metaphors – the tree, the river, the family. Now we model everything the left hemisphere's way, mechanically.

The right hemisphere seems to be involved more with new experience, new events, things, ideas, words, skills or music, or whatever it may be, while they are still fresh, original and unique, and so to speak present, to the mind. The right hemisphere's world is present – or more precisely ‘presences’ to us, as Heidegger puts it.

The left hemisphere abstracts and generalises, where the right hemisphere's world remains truer to each embodied instance, and appreciates the unique.

The neuroscientist V.S. Ramachandran calls the right hemisphere the devil's advocate, because it is always interested in the particular, upsetting the left hemisphere's tendency to collapse unlike into like, and see only what it is expecting to see.

The left hemisphere's world is a representation only. It is like a map, useful precisely because almost all the information about the land to which it refers has been left out.

The left hemisphere is not in touch with reality but with its representation of reality, which turns out to be a remarkably self-enclosed, self-referring system of tokens.

What do I mean by ‘betweenness'? Think about the nature of music. Music does not exist in one particular note – which is in itself meaningless; or in a lot of such single notes, each in itself meaningless.

The left hemisphere is especially good at voluntary and social expressions of emotion and one of the most clearly lateralised emotional registers is that of anger, which lateralises to the left hemisphere.

Deeper and more complex expressions of emotion, and the reading of faces, are best dealt with, however, by the right hemisphere.

The first evidence of this comes from about the fourth century BC – just as Greek culture was beginning to pass its peak. For the first time in Western civilisation the left hemisphere's take on the world started to dominate.

From the right hemisphere came careful observation of the natural world (the pre-Socratic philosopher Thales correctly predicted an eclipse of the sun); a sense of the uniqueness of the individual, with interests that needed to be harmonised with those of the community, which itself was seen as a living, changing entity that was more than the sum of its parts; and there arose, for the first time, wonderful, expressive depictions of the human face, narratives of human lives, and poetry rich in metaphor.

From the left hemisphere came the working out of the fruits of natural observation into useful predictions of behaviour of natural bodies, the codification of laws, the creation of maps, the development of some aspects of mathematics, the introduction of monetary currency, the further evolution of written language (at this point starting for the first time to be written, as now in the West only, from left to right), and in general the systematisation of knowledge.

We find Plato saying that the right way to do astronomy is not to look at the stars, but to look inside ourselves. And suddenly there is a flurry of interest in what was called paradox – when our theories about the world, our ways of thinking, come face to face with reality and show themselves to be inadequate to understanding the world.