In response to Scott Barry Kaufman’s article yesterday arguing the right-left brain hemisphere split isn’t true, the main proponent of the view, Iain McGilchrist, responds.

Scott Barry Kaufman would appear to be way behind the curve on the topic of hemisphere differences. It is true that there is a diminishing band of people – often life coaches and management seminar psychologists – who still go around mouthing the sort of nonsense with which he starts his article:

‘So yea, you know how the left brain is really realistic, analytical, practical, organized, and logical, and the right brain is so darn creative, passionate, sensual, tasteful, colourful, vivid, and poetic?’

This is, as should be obvious, a straw man, and underestimates his audience, most of whom can be assumed by now to have caught up with the vast increase in understanding of hemisphere differences in recent years.  It’s like lecturing us all on the news that physics no longer believes phlogiston to be the cause of fire. 

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There is a catch-22 involved here: we all learnt in our training that the sort of thing Kaufman puts forward was debunked ages ago.

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Increasingly cognitive neuroscientists are catching up with developments in this field, on which I have written at length in principally two books, The Master and his Emissary (Yale University Press 2009) and The Matter with Things (Perspectiva Press 2021). These books total approximately two thousand pages together, represent the results of three decades of research specifically into what the real hemisphere differences are, and are backed by the findings of over 6,000 papers in the area.  Fifteen years ago I still had to warn people that just about anything they thought they knew about hemisphere differences was likely to be either flat wrong, or at the very least in need of much qualification – and at worst the complete reverse of the truth.  I have had to do this much less recently; but Kaufman’s article shows how necessary it is for me to keep repeating it.

SUGGESTED READING Creativity is not a right brain phenomenon By Scott Barry Kaufman

Reading The Matter with Things alone would involve some hard work, I recognise, and I am not being dismissive of those who cannot find the time to read it carefully.  I completely sympathise: we live in a world in which we are constantly trying to catch up with so much. But the corollary is that those who have not read my work should think carefully before laying down the law on a topic they have not researched if they don’t want to seem out of touch. There is a catch-22 involved here: we all learnt in our training that the sort of thing Kaufman puts forward was debunked ages ago.  As a result, few people have had the foolhardiness – or courage, depending on your point of view – to take the necessary pains to investigate the real truth about hemisphere differences, because taking the matter seriously would not only involve them in years of work, but make it impossible for them to progress through the science establishment, since that establishment already appears to know, without having to look at the evidence that has by now accumulated, that there can be ‘nothing in’ hemisphere research.  But this is neither logical nor scientific.  Because the conclusions that were jumped to in the 1960s and ’70s were mistaken is not to say that there are no conclusions to be drawn. 

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All neural networks we know of are asymmetrical, even the most ancient; and the division of them into two neuronal masses is hundreds of millions of years old, apparently massively sacrificing computational power.

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Consider only this. All neural networks we know of are asymmetrical, even the most ancient; and the division of them into two neuronal masses is hundreds of millions of years old, apparently massively sacrificing computational power. Why? Asking difficult and neglected questions is how science progresses.  And asking these particular questions opens up many, many more that help us understand in far greater subtlety how the brain works. 

SUGGESTED VIEWING The dawn of consciousness With Donald Hoffman, Iain McGilchrist, Eva Jablonka, Michelle Montague

Of course, hemisphere differences are not the only things that matter in brain structure and function.  But they do matter profoundly, and their omission from our attempts to understand the brain mean that those attempts are radically deficient.  Of course, and for the umpteenth time, both hemispheres are involved in everything we do, and are in normal subjects always active together.  But that is not to say that they do not contribute in a consistently different manner that has great significance for the human subject.  Seeing this means understanding phenomenology, not just the ‘wiring diagram’, since the brain is not just some technical gizmo but the very pathway of human experience.  Nonetheless, the so-called wiring exhibits differences at all levels, too: the hemispheres differ in size, weight, shape, sulcal-gyral pattern (the convolutions on the cortical surface), neuronal number, cytoarchitecture (the structure at the cellular level), neuronal cell size, dendritic tree features, grey to white matter ratio, response to neuroendocrine hormones and degree of reliance on different neurotransmitters.

We should be interested in this.

There is so much more to say about all this, but it is already laid out in detail in my books – indeed the first steps are in the very introduction to The Matter with Things (and to some extent in the preface to The Master and his Emissary): so rather than take up a lot of space repeating myself here I refer any interested reader to those books.  Kaufman sets up only straw men.  Of course ‘creativity does not involve a single brain region or single side of the brain’: nothing does. And, of course, as I point out in The Matter with Things, ‘depending on the stage of the creative process, and what you’re actually attempting to create, different brain regions are recruited’. 

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Science progresses, as Max Planck said, one funeral at a time.

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Creativity is an interesting, and instructive, case. Although most of the old canards are wrong, it turns out that there is much truth in the idea that the right hemisphere is more important than the left in true creativity. (It would make my life easier if this wasn’t the case, but I have to follow the science.)  A central problem in the research into brain correlates is that it is difficult, to say the least, to get people to ‘be creative’ to order, for the purposes of experiment: great artists and original scientific thinkers alike make clear that creativity cannot be summoned in this way. As a result, routine tasks, such as finding as many uses as possible for a coat-hanger, substitute for what was done by Mozart. This matters because tasks that are minimally creative often engage left hemisphere regions, while highly creative tasks show a strong tendency to engage right hemisphere regions. The selection of subjects also matters: more highly creative individuals rely on the right hemisphere to a considerably greater extent than less creative individuals; less creative people, it seems, rely more on linear, sequential, mechanical procedures for coming up with new ideas. There are other difficulties. Many of the studies on creativity are wholly or partly linguistic in nature, involving reading, speaking or generating words – or all three. Language alone inevitably recruits more left hemisphere areas than a non-linguistic creative task, skewing our assessment of creativity per se. Moreover there are specific problems associated with the interpretation of each mode of investigation (eg fMRI, EEG or ERP). This is why a careful examination of the deficit literature, especially in real life artists, poets and composers, is so important: there the evidence is overwhelmingly in favour of the right hemisphere, not the left, being the principal brain substrate of creativity. 

In summary, the overall evidence suggests that the right hemisphere is essential to the process of creativity; the left hemisphere, though it may play a part at certain points, is of secondary importance, when it does not actually impede creativity (suppressing the left frontal region increases creativity in experimental subjects). The discussion of the evidence in The Matter with Things is 65 pages long (Chapter 8), not including an 11-page appendix (Appendix 1) taking a critical look at the claims made by opponents in this field. Here I’ve made just a few observations: for a closer look, I’d encourage the reader to refer to The Matter with Things. 

I shall not labour the obvious. What we need here is more intelligent, subtle, philosophically and neurologically sophisticated investigation into the topic of hemisphere difference, not some sort of slapstick dismissal masquerading as science. Science progresses, as Max Planck said, one funeral at a time. I believe that young neuroscientists, who are already writing to me because they are engaged with my work and that of others in the field, will carry it forward: I do not expect the die-hards to change.