NEUROSCIENCE AND PSYCHOLOGY

Myths and Ideas About the Two Halves of Our Brain — Part 8: Last but not least, the polarising theory of Iain McGilchrist

Iain McGilchrist’s theory about the brain’s hemispheres ties in trends in modern history and gives advice on how to cultivate mental health

Recap

We’ve covered a lot of territory in this series, and today we’ll bring things to a close. Let’s quickly run through what we’ve covered until now.

In our tour of the hemispheres so far, we’ve debunked two myths: the logical vs creative myth, and the myth of left brain dominance. We also described one theory from Elkhonon Goldberg. Elkhonon’s theory (more formally known as the novelty-routinisation hypothesis) argues that brain functions can be organised along a continuum. This continuum is defined by novelty at one end, and familiarity/routines at the other.

Elkhonon’s ideas map fairly neatly onto the hemispheres, with novelty identified with the right hemisphere, and familiarity/routines identified with the left hemisphere. In addition to the left-right dimension, Elkhonon’s theory also maps onto the brain’s front-back dimension. That is, novelty is associated with the frontal cortex, whereas familiarity/routines are associated with the posterior cortex. As an extra layer of complexity, researchers have found sex differences in brain organisation/function along the left-right and front-back dimensions. These differences are interesting but poorly understood and need further study.

Elkhonon’s theory explains, or is at least consistent with, many findings related to the hemispheres. But I personally think that some of his arguments are a bit tenuous. We covered some of these doubts at the end of the previous article. Take the irrepressible overconfidence and detachment from reality that we sometimes see after right hemisphere strokes, but which usually do not occur following left hemisphere strokes. Can we really explain this by appealing to differences in whether the hemispheres prefer novelty or familiarity/routines?

Or take the left hemisphere’s deep-seated need to act like it always knows the exact reasons for our own actions. Studies with people who underwent so-called split-brain surgery found that the left hemisphere is happy to admit that it doesn’t have an answer when the question involves random facts. But the situation is different when the question relates to our own behaviour.

Using clever experimental designs, researchers like Michael Gazzaniga discovered that the left hemisphere would rather lie than admit it doesn’t know the reason(s) behind our actions. I don’t know about you, but for me, this pattern of findings is not well explained by the left hemisphere having a preference for familiarity/routines. To better explain these and some other findings, I think we need more ideas: enter Iain McGilchrist.

Iain McGilchrist to the rescue

In 2009, Iain first published his theory in his book The Master and His Emissary. The book made a surprising splash, given it’s about 500 pages long and draws deeply on a number of obscure and diverse topics. Thanks to Iain’s training in many disciplines, this ranged from psychology and biology to the history of philosophy, literature, and art. A documentary about it was also recently released. But as you can tell from the title of this article, his work has also been received with some controversy.

The controversy is mostly a storm in a tea cup, as researchers are often too reluctant to give credit and overly keen to give criticism. Even if Iain’s ideas turn out to be wrong, there’s still value in ruling them out. But because Iain makes big claims, he’s sure to be scrutinised and criticised. We’ll talk about those criticisms as we make our way through Iain’s ideas. The long version would take a whole new series, so let’s go with the short version.

How are Iain McGilchrist’s and Elkhonon Goldberg’s theories similar?

Iain’s theory argues that the hemispheres each have a different way of understanding and interacting with the world. Said another way, the hemispheres have different kinds of awareness or different ‘takes’ on the world. For Iain, this is rooted in a point that we discussed in the first article: having two different but complementary halves makes the brain work more efficiently as a whole.

So how do the worldviews of the two hemispheres differ? A key difference is whether they prefer to think of parts or wholes. In Iain’s theory, the left hemisphere sees the world as made up of parts. This favours a mechanistic worldview that tends to diminish the role of context, and promotes a focus on features and innate properties.

In contrast, the right hemisphere sees a world made up of whole entities. This brings a different focus, one that emphasises the relations between things. This favours a less mechanistic worldview that tends to highlight the role of context. In this perspective, properties emerge from the relations between things, not just the things themselves.

Iain’s theory helps to explain various findings related to the hemispheres, and is compatible with Elkhonon’s ideas. For example, the right hemisphere is usually better than the left hemisphere at identifying faces, and most cases of face blindness (prosopagnosia) involve damage to the right hemisphere. In light of Iain’s theory, these results make sense, as a face is a whole entity, and should be up the right hemisphere’s alley.

By contrast, the left hemisphere’s feature-based strategy is much less effective. As a consequence, the left hemisphere’s facial recognition skills are about the same regardless of whether the face is presented upside down or right side up. In fact, upside down faces are sometimes easier for the left hemisphere to identify, as this places greater emphasis on facial features over whole faces.

So how is this compatible with Elkhonon’s theory? The left hemisphere’s preference for parts and features with innate properties would make most sense when items are highly familiar. As for the right hemisphere, its focus on wholes, relationships, and the role of context would make most sense when dealing with things that are highly novel and/or unpredictable.

You could even debate whether one theory can be reduced to the other. For example, does a preference for familiarity/routines drive a focus on parts and features, or vice versa? But by imagining that the hemispheres have a worldview, like a type of personality, Iain’s theory goes beyond Elkhonon’s in many ways.

How are Iain McGilchrist’s and Elkhonon Goldberg’s theories different?

Iain’s theory argues that the hemispheres have different temperaments and expectations of the world. The left hemisphere loves to analyse parts to reveal properties and lump things into neat and distinct categories. This is an invariant world where things have an innate nature, context is minimally relevant, and things are not expected to change.

This perspective co-occurs with (or may even be the cause of) a general optimism and self-confidence on the part of the left hemisphere. We see this in the cases of US Supreme Court member William Douglas and US president Woodrow Wilson. Both denied their paralysis following right hemisphere strokes, held lofty ambitions for future success, and remained boldly adamant that they could do anything.

This may help to explain the overconfidence of the left hemisphere when it makes up stories to explain our behaviour and then passionately believes its own lies. However, it doesn’t explain why the left hemisphere is happily ignorant about some things, but then specifically pretends to be in the know with respect to our actions. That mystery remains unsolved.

I could prattle on and on, but one last point helps to flesh out Iain’s theory and brings us to the controversy among researchers. In addition to what we’ve said so far, Iain argues that the left hemisphere has a more literal take on the world. He connects this to the left hemisphere’s preference for parts and features with innate properties, and its heavy use of explicit language rules, being our primary seat of language. It also tends to focus on the short term, and prefers to see the world in black and white categories.

In contrast, the right hemisphere has a less literal take on the world that better appreciates more subtle, implicit forms of meaning, such as metaphor, tone, body language, and humour. Iain’s theory links this to the right hemisphere’s focus on wholes, relationships, and context. It also better appreciates the long term, and is comfortable with shades of grey.

Controversy corner

So where’s the controversy? It’s not easy to gauge the spread of opinion on Iain McGilchrist’s ideas. Some have lauded his work as a major achievement, whereas others (I want to say most) criticise Iain for speculating too broadly about the brain without enough evidence. Only time will tell the truth of it, but for what it’s worth, he has many readers who say that his book has changed their lives for the better.

Much of the controversy is related to some of Iain’s grander ideas related to society and the course of history. For example, Iain suggests that the virtue of the left hemisphere’s perspective is that it allows you to act upon the world. You can think of it as the hemisphere that permits you to gain mastery over your surroundings.

The virtue of the right hemisphere’s perspective is that it appreciates more subtle and complex information. Evolutionarily, we’re a social species that lives and dies by its ability to understand many unwritten and complex social rules. Historically, we’ve also lived in environments that were dangerous and constantly changing. In this setting, the holistic awareness of the right hemisphere would be very valuable, and we could end up in big trouble if we rely too much on an overconfident left hemisphere.

But Iain doesn’t stop there. He submits a formidable body of literary work from across recent centuries to argue that the West has become caught in a kind of Matrix of the left hemisphere. I won’t be able to do his argument justice, but he suggests that many of our current problems stem from overdependence on the left hemisphere’s worldview.

This is the mechanistic world of things with parts, features, and innate properties. Here, context is minimally relevant, the world exists in black and white, and the short term is king. Anyone who’s read my articles on emotions and chaos will recognise many of these as tenets of WEIRD psychology.

Iain strongly advocates for the value of the right hemisphere’s perspective. This is the world of wholes, relations, and collective, emergent properties. Here, we understand the long term, and appreciate shades of grey. This type of perspective also tends to see processes with dynamics rather than things with properties, which suits Iain’s tastes as a process philosopher. (Process philosophy is the topic of his new book, ironically named The Matter With Things.)

To back this up, he cites research on quality of life after brain injury to support the idea that, if you had to choose one hemisphere to be stuck with, you should go with the right hemisphere. As a general rule, Iain argues that the left hemisphere gets too much credit for our mental skills, and the right hemisphere gets too little.

This is where Iain receives the most pushback from researchers. I’m not sure who’s right and wrong, since his argument spans centuries of European philosophy, art, and literature that I’m honestly never going to wrap my head around. But given the sheer scope of his argument and the big claims he’s making, this sort of thing is sure to inspire opposition. All I can say is that Iain seems to be honest and just wants to improve people’s lives, so hopefully the field makes constructive progress.

The end

This is the end of the series. We started with a recap, so we won’t run through a final summary. Especially for those of you who’ve read from the beginning, thank you and I hope you found this series interesting. There remain many more mysteries than answers when it comes to the brain. But with respect to the hemispheres, the theories from Elkhonon and Iain are the best we currently have, at least in my view. If something new comes up in the future, I’ll be sure to check back in for an update. Until then!