Prof Bruce Hood
Bruce Hood is an experimental psychologist who specialises in developmental cognitive neuroscience. He is the director of the Bristol Cognitive Development Centre at the University of Bristol. As well as publishing a number of successful popular science books on this subject, he also gave the 2011 Royal Institution Christmas Lectures.
When you understand that there are minds, then you draw the distinction between the mind and the body
On becoming interested in science
Well, what got me most interested about the mind I suppose was discovering that the paranormal was not real. Like everybody else in the 70s and 80s, I was amazed by the reports of psychic abilities and watching Uri Geller on television and if you believed the media at the time then it seemed that these were all the untapped powers that we could harvest. But on getting to university and actually looking into the field of psychology I discovered that there was absolutely no evidence for these psychic abilities and so, you might think that that might have been a disappointment, but in fact I discovered a much more interesting field of studies of empirical work on the mind, because it struck me that the mind was somehow unmeasurable but in fact it is very measurable and that’s something that most people don’t appreciate.
So I suppose it was that about turn, as it were, on the falsehood of psychic ability which turned me onto the empirical study of the mind.
Well, that would’ve been as an undergraduate, I started off doing philosophy and economics and mathematics and found them dreadfully boring, so I took psychology and within psychology I discovered there were some interesting areas, got very excited about children and then pursued that from then on.
On the birth of neuroscience
I think the mind has always been something of interest to scholars and clearly the classical philosophers talked about the mind and Descartes talked about the mind, but they didn’t really have any kind of mechanical understanding or mechanistic approach to it. It wasn’t really ‘til the 19th century with Helmholtz, the German who started to show that you could actually measure the mind, you could actually record and study it empirically…reaction times for example, he was the first to demonstrate that nerve impulses are not instantaneous, they take a time to travel. So he worked out that it was a system which had, kind of, limits and that was a real beginning to understand that the mind is a product of a machine i.e. a biological computer which is the brain.
So I think really the 19th century I would trace as the origin of starting to ask the right questions about what the mind is.
On PhD research
OK, so one of the areas I worked on in my PhD was the control of the eye movement system in very young babies, so the brain is undergoing significant development over the early months and we make a division between systems which are low down and secondary systems which we call the cortical systems which are all the higher functioning areas. In a very young baby the higher functioning area is not online, as it were, but you can see a transition in the early months as they start to get more control over their behaviours. So that manifests in terms of movements but also the way that they move their eyes around, which was my particular interest. So a very young baby, if you look at a newborn, they look almost as if they’re drunk, they’ve got this “glakey” expression as we say in Scotland, fixed gaze and that’s because they don’t have the control of the eye movement system to voluntarily scan the scene around them, but round about two or three months of age you can see suddenly a transition in their behaviour as they start to inspect and interpret their world.
And so it has major consequences so that they can look at faces differently, they can scan faces, they can voluntarily just, you know, look wherever they want to. So that’s an example of a system which we knew was operating in monkeys that we then looked at the emergence of that in humans and we could explain human behaviour by appealing to animal models and brain mechanisms.
On blaming the past
A lot of lawyers are indeed trying to pull this act by saying, well, you know, they’ve got a brain tumour or a brain disorder and you’re getting rid of responsibility and clearly as our technologies and our understandings of the brain improve, we’re going to find more and more cases where we can explain away some anomaly, but that doesn’t mean that we should get rid of culpability or indeed punishment because these are also factors which enter into the equation about how to behave. So just because you are kind of a psychopath or you had a bad childhood, that doesn’t mean that you’re not responsible or that you shouldn’t be punished; punishment in its sense is another factor which changes or should change your behaviour, it’s another constraint. But it also reveals that punishment wouldn’t necessarily always work and indeed if anything shows us, you know, the criminal system shows that incarceration is generally pretty poor in changing people’s behaviour.
So I think it’s a difficult question and, um, you’re entering into people’s issues about revenge and, you know, what society wants, but I don’t think it’s anything a neuroscientist is really going to be able to answer for you.
On the critics of neuroscience
Yeah, I think the problem is the promise of understanding or mapping the mind about 20 years ago. There’s something very seductive about brains, ‘cause we all kind of realise this is what we are and so when the first sort of neuroimaging first appeared, this was leading articles in the major journals and it created this enthusiasm and storm of activation and interest in brain imaging. But of course we know that these things happen in your brain and not your big toe so it’s probably no surprise to find activation in the brain area. But the extent to which you can use the localization…I think it smacks a little bit of what is effectively neo-phrenology, trying to kind of localise functions down to a specific area. Unless you’ve got a very good reason why an idea or behaviour should be localised, then I don’t think imaging actually helps in any sense, it’s only a tool for helping you build models, ‘cause clearly all the brain is involved in decision processes. So whilst imaging has been useful, actually localising a function hasn’t actually elucidated what’s going on, it just doesn’t help you. If you, for example, have an idea that two behaviours differ because they recruit different mechanisms and you also find that under these two behaviours, you stick someone under the scanner and indeed they do show up as different activations, then you’re on a better grounding to say that in fact the evidence supports that that’s the right assumption. But just localisation on its own is not sufficient evidence or indeed any level of explanation.
On a naive theory
So I work in children’s conception development, I’ve worked on all aspects of development from eye movements up until beliefs about ghosts, but we think that children aren’t entirely blank slates, in other words they’re just not empty receptacles for all the information for education; before they even go to school, children have some understanding of the world around them, so they have ideas about the physical world, the living world and indeed they also think about other people having minds. And they have what we call naive theories, they’re naive in the sense that these are not taught to them and very often they include misconceptions. So it’s these misconceptions which I think reveal the universal aspects of the way that children think about the world. So we’re always looking for these naive universals because they reveal the natural architecture of the mind as it’s unfolding.
We’re not particularly interested in how best to educate children although, of course, having an understanding of what the child’s naive understanding is is a really good way and should be integrated into the way that we teach them.
On adult ‘magical reasoning’
Well, for example, when they start to understand the mind, when they start to have an understanding of their own mind, first of all they find it very difficult to understand that someone else has a mind which is different to their own, so they’re very what we call egocentric, they’re very self-centred. But once they understand that other people have minds, they understand that they can have misunderstandings, false beliefs, and so they can start to lie, you know, we celebrate birthdays, we should also be celebrating the child’s first lie day, ‘cause when a child lies that demonstrates that they know that they can manipulate your ideas, basically, distorting the truth.
So when you understand that there are minds, then you draw the distinction between the mind and the body and that’s what we call mind body dualism, and most adults if you ask them believe that the mind is somehow separate to the body, but if you’re a material neuroscientist like myself, you think the mind must be a product of the brain. Now every child eventually comes to understand that the mind is different to the body, but if it’s different to the body and separate from the body then maybe it can exist when has gone, so mind body dualism is a basis for spiritual beliefs about the afterlife.