The two hemi-spheres of experience

Since my early twenties, Zen Buddhism has impressed me as it quite deliberately uses words and the paradoxes that can so easily be generated through them to point beyond the verbal and abstract to immediate experience.

In The Master and His Emissary, the professor of literature and now psychiatrist Iain McGilchrist unfolds this theme across the range of western thought, art, science and society. More centrally, he relates it to his strongly held hypothesis that the two theses of this dialectic of word and experience are manifested in, if not directly the expression of, the two very different modes of functioning of the hemispheres of our cerebral cortex. This could have resulted in a reductive neuro-pseudo-explanation of significant and subtle aspects of our subjective experience. However, his original education in English at Oxford and distinguished early career teaching English literature, also at Oxford, informs McGilchrist's broad knowledge and deep appreciation of shared humanity and its expression in Western culture, and this keeps his account humanely grounded.

In questions after his talk at Royal Society of Arts (RSA), parts of which are available online, McGilchrist is asked if he is concerned that, as with previous enthusiasms for brain laterality, his quite subtle work will be over simplified. This review will no doubt confirm his expectation that this is inevitable. It seems to me that this inevitability is itself an expression of his major hypothesis: Whether we are trying to convey a perceptual or inner experience, or to discuss a significant cultural work, our immediate experience of it and our verbal reconstructions of it are incommensurate and, in some ways, competing perspectives on the aspect of the world in focus.

McGilchrist's book is in two major sections. The first is a thorough exposition of evidence supporting the contention that our experience is a synthesis of two distinct ways of integrating perceptions of self and world, and that each of those is more strongly characteristic of one cerebral hemisphere than of the other. The evidence is derived from an assortment of sources of which McGilchrist gives the most weight to those deriving from so called "split-brain" patients and from patients and experimental subjects who have, either through surgery, stroke, injury or temporary chemical or electro-magnetic intervention, lost the function of one hemisphere.

The second section is an exploration of cultural change, primarily in the west, in the light of the two modes of experience described in the first section. This exploration begins in pre-Homeric literature and focuses on the transitions in Greek thought from the appreciation of change and uniqueness in Heraclitus and Aristophanes, through the transition he sees toward ideal, unchanging forms in Socrates, Plato and, with qualifications, Aristotle. He touches on the Roman adaptation of Hellenic culture, skips through the Dark Ages and then maps the cycling of later European thought across the hemispheric dialectic, from Renaissance to Reformation, Enlightenment to Romanticism to Modernism and Post-Modernism. He surveys literature and philosophy, visual art, and music. The presentation in both sections is extremely thorough and a common reaction among other readers is that there's too much detail and repetition.

Recapitulating his thesis, we have two major modes of experiencing the world. The first, and in his view the primary mode, is characterised by, among other descriptions, Gestalt (instant awareness of a whole comprised of many parts); awareness of transition, transience and change, therefore of process and relation; awareness of "the other"; awareness of relatedness; awareness of the uniqueness of the particular aspect of the world to which we're currently attending and how the whole(s) it contributes to is/are given meaning by the parts and their relations, thus organicity or the life-world. The second is characterised, again partially, by categorisation; by perception of stasis and boundaries; by self-reference; by the conditioning of the object of attention according to the categories of which it is seen to be a member; awareness of regularity and sameness; symmetry; utility (to me, the user); tools and the mechanical. The first mode is predominantly that of the right cerebral hemisphere, the second mode predominantly that of the left.

Note that these differentiations aren't so much functional differences as modal or hermeneutic differences; differences in how material is interpreted rather than differences in what material is processed. So, even though we conventionally (and erroneously) think of language as strongly biased towards the left hemisphere, McGilchrist makes very clear that, as with almost all functions, each hemisphere contributes its own particular style and function to the understanding and production of language. So while the left hemisphere "owns" vocabulary and syntax, the right "owns" meaning both in construction and interpretation and, particularly, of metaphor and implicit meaning. In a phrase, "if it is the right hemisphere that, in linguistic terms, paints the picture, it is still the left hemisphere that holds the 'paint box'". (p. 99)

Also, while it is easy to caricature and valorise each hemisphere (the holistic, fluffy, wordless, New Age right versus the precise, pedantic, articulate, anal left), human intelligence and judgement are at their best, their most humane, when the two modes contribute appropriately: each is, or rather, both are essential to optimal human functioning. The picture McGilchrist paints of ideal functioning is cyclical: primary apprehension of the immediate world by the right hemisphere, interpretation of that apprehension in terms of utility and (self-centric) abstractions by the left hemisphere and a return of the interpreted material ("re-presented") to the right hemisphere for integration. I will only mention here details that he discusses like the evolutionary shrinkage of the communication channel between the hemispheres, the corpus callosum; or the essentially inhibitory relation that the hemispheres bear to each other: each is a nay-sayer to the other; or the appearance of hemispheric division quite early in mammalian evolution. All of these and more add depth and subtlety to the story's unfolding.

His major contention is that the swings in western culture between the two hemispheric modes have tended increasingly to emphasise the left hemisphere's preferences. As our technological progress has interposed ever thicker insulation between us and the physical world in which we are embodied, our lives have been increasingly mediated by abstractions. Mediated, that is, by and evaluated via the syntactical and terminological characteristics of language and other symbol systems: exactly the forte of the left hemisphere. Simultaneously there has been a corresponding reduction in cultural value of immediate embodied experience. It is quite easy today to live a life which primarily features interactions with and via computers, and more or less passive consumption of virtual, usually visually presented, entertainment with very limited exposure to contingencies of the physical world. Exceptions include (one hopes) driving a car, though the increased prevalence of texting and phoning while driving is eroding this interaction with physical reality. McGilchrist includes an amusing but worrying anecdote illustrating the primacy that spoken language can take over physical reality for some while driving.

The subtlety of McGilchrist's presentation and what makes it a deeply human work is his appreciation of co-creation between world and knower. He emphasises the "betweenness" relation of subject and object that is a central aspect of the right hemisphere mode of sense-making. A major theme he returns to across several aspects of cerebral processing is of a reciprocal relationship between, for example, attention and the world attended to. He says:

"Our attention is responsive to the world.... We pay a different sort of attention to a dying man from the sort of attention we'd pay to a sunset, or a carburettor. However, the process is reciprocal. It is not just that what we find determines the nature of the attention we accord to it, but that the attention we pay to anything determines what it is we find.... Attention is a moral act: it creates, brings aspects of things into being, but in doing so makes others recede."(p. 133)

This is reinforced by his observations about context. Once again there is a reciprocal relationship between our perception of an object being conditioned by the context in which we find it and our perception of context being conditioned by the objects which perception identifies. This is reminiscent of Dennett's "multiple drafts" model of the mentation underlying consciousness, probably because it shares an evidentiary basis. We construct context from percepts which, perhaps as "hypotheses" of objects, modify the presumed context, which in turn selects against particular object-hypotheses which again modify the contextual possibilities until we get mutually consistent maps of objects/contexts. Double or ambiguous images such as the Necker cube or duck-rabbit, included by McGilchrist, are phenomenologically salient examples of this un- or pre-conscious resolution of ambiguous context/object settings.