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Entrainment

This is a post about my current 5-year fellowship from the European Research Council. The aim of the fellowship is to look at how infants’ biological rhythms entrain to their social and physical environment during early life. It’s a pretty big (and complex!!) project – so here is a rough overview of what we’re going to be working on…

Currently, when we as scientists to understand the factors that drive individual differences in cognitive development in children, there is an overwhelming concentration of interest in executive functions. Although never explicitly stated, the implicit metaphor behind much of this research is that of Descartes’ ‘ghost’, driving a machine. Children who are better able to maintain attention towards tasks or play activities in real-world settings, and who are less easily distracted by extraneous stimuli, are thought to have better endogenous (volitional) control over the focus of attention. Broadly, they are considered better able to control when the starts and stops of naturally occurring attention episodes occur; they are better able to switch between different attention-eliciting stimuli; and they are better able effortfully to maintain attention to a particular target.

Sam’s Crystal Ball (TM) says that in 20-30 years this approach isn’t going to be so popular. I think that the idea of being able to measure an individual’s ‘pure’ endogenous control capacity will be seen as reductionist – like the ‘black box’ approaches from the 60s and 70s that are now widely criticised. To start with, we’ve got the problem of construct validity: most experiments used to measure executive functions measure it in settings that are fundamentally different to any real-world setting, and the small number of studies that have looked have generally found that the experimental measures don’t even correlate with the same thing measured in a real-world setting. The second problem is that training studies are increasingly showing that training endogenous control improves performance on the tasks used to measure it – but these improvements don’t transfer to altered real-world behaviours in any measurable way. This is causing many researchers to challenge the strong theoretical claims made based on correlations observed between EFs and real-world behaviours.

So what types of approach are going to be more popular in 20-30 years? Well, I’m putting my money on a shift away from approaches that aim to locate abstract mental functions in an individual, and towards embodied approaches that emphasise the inter-relationship between the individual and their social and physical environment. So for this project, rather than concentrating just on what’s inside us, we’re instead concentrating more on studying the world around us, and the relationship between us and the outside world. Reflecting that, and rather than thinking of metaphors about ghosts driving machines, we’re instead thinking in terms of new metaphors, that reflect this inter-relatedness: such as ‘children as oscillators’ or ‘children as reverberators’.

This world is incredibly complex, with complex temporal patterns in the environments that we live in, in other people whom we interact with, and at different bio-behavioural levels in ourselves. And we know that the inter-relationship between us and the temporal patterns around us is important. When we pay attention to temporal structures in the outside world we ‘tune in’ to them – i.e., the activity patterns inside us start to look more like the activity patterns outside us, that we’re paying attention to. (eg, eg, eg). But we know astonishingly little at the moment about how this process develops over time.

Some of the measures that we will be collecting to look at entrainment

For this project, we won’t be collecting too much data using artificial, reductionist paradigms aiming to measure abstract mental constructs. Instead, we’ll be collecting real-world, naturalistic data with as little experimental interference as possible. This will include home recordings using wearables (see below) and free-flowing naturalistic interactions in the lab – trying to collect as many different measures, across different timescales, as we can.

What will we do with this data? The main aim is to look at how the temporal activity patterns within us are influenced by the temporal activity patterns that we experience in the outside world. To do this, we’re doing a lot of work at the moment (eg, eg, building on eg, eg) about different methods that we can use to measure this. (Like everything it starts off as an easy problem and gets harder the more you think about it!)

Using these we can look at entrainment at three levels. First, we can think about within-individual entrainment: how the phase or period of oscillatory activity in one brain region is affected by the phase or period of oscillatory activity in another brain region (or between levels – e.g. between physiology and brain activity) (eg, eg).

Second, we can think about stimulus-brain entrainment: how oscillatory activity in an individual child is affected by oscillatory activity in the environment around them. In developmental research there is, for example, some research looking at how infants’ brains entrain to temporal patterns in speech, and how this can go wrong in atypical development.

Third, we can think about inter-personal entrainment: how oscillatory activity in an individual child is affected by oscillatory in other people around them. We can look at this in the brain, in physiology and in behaviour.

The six PhDs working on the project all have different aims, and approaches – you can read more here. But overall I guess there are two main questions that we’re looking at:

The first is: do we actually entrain to patterns around us? For example, there is a recent debate (eg, eg) about whether the finding that adult brains entrain to language – which had been thought of as an established finding – may instead be explained by the brain ‘just’ showing a series of evoked, unpredicted responses that just happen to take place regularly. But there is an enormous amount that we don’t know – about whether entrainment is something that develops over time, about inter-personal entrainment, about long-term entrainment (e.g. children raised in chaotic/unpredictable homes) and also about entrainment across different time-scales (for example, low-frequency fluctuations in the parent might ‘gate‘ high-frequency fluctuations in the child).

And the second is: how is the emergence of endogenous control in infancy – that is thought to occur around the 12-month age boundary – characterised by changes in the how we entrain to the environment, and those around us? On the one hand, most authors talk about a transition from co-regulation of affect and arousal across the parent-child dyad to self-regulation within the individual over time. So does this mean that our affect and arousal are more dependent on our environment and on people around us early in development, and become progressively less entrained over time? On the other hand, entrainment in adults is thought to arise as a consequence of us choosing to pay attention to something – so based on this we would make the opposite prediction – that entrainment should increase over time, as our capacity for directed attention increases. At the moment, nobody knows…

So – lots to look at! Get in touch if you want to hear more.