Cognitive Variability

Neuroscientist Michael Thomas on differences between children, computational modeling, and the new skills that our species acquired

videos | July 28, 2017

One of the areas I carry out research in and one of the focuses of my research laboratory is the idea of cognitive variability. For me variability comes in many different forms: you can see how we seem to get cleverer as we get older, what we can do as children but not as young babies, what we can do as teenagers but not as young children, so there’s a change in our cognitive abilities over age. But also take children of a given age, six-year-olds, you may find that some six-year-olds are more able than other six-year-olds. There’s variation even within an age. You can find extremes, you can find developmental disorders, you can find giftedness. And there’s variation at the end of our lives as aging sets in. For me it’s important to link together all these forms of variability, because I think common mechanisms can underpin them all.

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I use a particular method to try and study that which is called computational modeling. I actually build simple computational models which try and study development across the lifespan. What I do is I don’t just build one model, so this might be like a model of a simple brain, an artificial neural network, you put it in an environment, it changes its connections as it experiences things, it acquires certain behaviors. If you model development like that in terms of an interacting system acquiring abilities, you can begin to understand how variations in the qualities of experiences but also variations in the property of the learning mechanism might influence how well it develops. And then you can simulate large populations of these learning systems and begin to understand how development might show variations that some may be developing more quickly and some more slowly. So what I’m trying to produce in that research is a kind of integrated framework for thinking about how cognition can vary across age, can vary within age.

Now when you do that, you begin to get some important insights about where psychology is as a field at the moment. I think, one of the problems in psychology is – it’s been set up around certain kinds of disciplines, certain kinds of divisions. And it’s a sensible idea, we can’t study everything at once, we’ll split it into separate problems and will have separate groups of researchers study each of their problems. So within psychology we might have one group of individuals studying development, trying to find how children get better, get cleverer, as they get older. What they’re interested in is characterizing the development of the average child. And then another group says: well, we’re interested in differences between people, individual differences in intelligence. We’re not going to look at differences across age, we’re just going to take a cross-section, at all children of this age, and will look at differences. And then another group says: well, we study disorders.

I think, it’s a problem when you study these things individually. It’s like taking a 100m race. You might have separate people trying to say, well, we’re trying to work out how the runners get from the beginning to the end by averaging together all of the individuals, we’ll just have an average runner. A separate group of individuals will say: we’re trying to understand the causes of who’s in the lead and who’s behind at a given point in the race. I think, this causes problems in separating between those different divisions of labor, as it were, because ultimately, as I indicated, what you have is a set of individuals undergoing a process of development. And that process of development is constrained or influenced both by genetic influences in environmental influences. And what one needs to understand first is the process of development as it applies to all of us, and then the factors that modulate the process of development.

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Take the field of genetics at the moment. Genetics focuses on looking at genetic variation and seeing how it relates to variations in trait: height, intelligence and things like that. So it’s focused just on individual differences and the genetic causes of individual differences. But it tells us absolutely nothing about, it’s blind to the processes that we all share. So people think genetics is about what does it mean to be a human – why can I talk and gorillas can’t talk? The kind of genetics at the moment really can’t tell you much about that, because it’s just focusing on the differences between humans and how the genetic variation on the genome produces those differences. So that lack of integration between how we all develop and how different factors modulate that development could ultimately render that the entire field of genetics as somewhat askew to some of the key questions about how we develop as a species.

So let me narrow that down to something concrete: take intelligence and our cognitive abilities, and how we think. You might hear that those are highly heritable, that genes are very important in deciding how clever we are and what kind of skills we can do. And you might think from that that somehow genes are limiting us in what we’re able to do. But those genetic effects are just about the differences between people.

So let’s go back 50 years ago. No one knew how to use a smartphone, no one knew how to use a tablet, no one had that skill. 50 years later most of us can use smartphones and tablets. Our brains are different. The human brain now has structures for swiping left and swiping right. It’s a completely different skill that we as a species acquired. And all of this genetics of intelligence – that might make us think we are constrained in what we’ve learned. But think again, here is a population, and you might find that some individuals are a little bit better at using smartphones, some individuals are a little bit worse at using smartphones. Maybe the differences between them, between how clumsy you are at typing text messages, maybe some of those differences are coming from genetics. But all of that is separate to the fact that over a generation we as a species have acquired a completely different skill. I think, it’s very important to try and think about a mechanistic basis, how you can integrate processes that affect us all as a species, that don’t much vary between us, with the kind of lesser differences you see between members of the species.

The further steps of taking this approach forward are to try and remove the barriers between these disciplines. In fact, you could be more radical than that with current interdisciplinary approaches, you could reorganize universities around researchers to solve problems, rather than having them in separate disciplines and then trying to get different researchers to work together.

In this case, within psychology the problem is coming in splitting between different forms of cognitive variability. What we need to do is to take a more mechanistic basis to think about causal mechanisms, to understand lifespan development and the processes that produce, that underpin biological development, cognitive development across the lifespan. Once we have that basic account, then we can think about how genetic influences or environmental influences modulate the trajectory of development. Whereas if we don’t have a fundamental platform or foundation in understanding how development works for everyone, it’s almost a distraction to look purely at the causes of variation.

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If this approach is successful, I think, we have a more realistic understanding about the potential for our species, about what kind of cognitive skills we could acquire in a hundred years or 2 hundred years. Our genomes may be the same, but one of our universal characteristics is brain plasticity, is having a large volume of association cortex that’s plastic, and we can acquire new kinds of skills. We retain our senses, we retain our motor skills, there are some limitations we have in how much we can keep in mind. But there’s a great deal of plasticity and potential even given our genomes to acquire new, perhaps, unimaginable in the future.

Professor of Cognitive Neuroscience at Birkbeck, University of London, the Director of the Centre for Educational Neuroscience
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