On language development and longitudinal research, with Courtenay Norbury

Professor Courtenay Norbury is a psychologist and speech-language therapist at UCL who specialises in language, cognition, and social interaction across a range of neurodevelopmental conditions.

You can read more about Courtenay's work at her lab website here and follow her on twitter here.

During this podcast she chats to Sue about SCALES, a 10-year longitudinal study that has been tracking the development of a large cohort of young children from school entry to Year 9.

The following is one paper from the study discussed in the podcast:
Norbury, C. F., Vamvakas, G., Gooch, D., Baird, G., Charman, T., Simonoff, E., & Pickles, A. (2017). Language growth in children with heterogeneous language disorders: a population study. Journal of Child Psychology and Psychiatry, 58(10), 1092-1105.

Many thanks to Naomi Meiksin for editing the transcript for this episode. 

Transcript

Intro: 0:09

Oh, it is recording, I see the little figure. Okay, great. I will do my little spiel and then I'll introduce you. Nice, okay.

Sue: 0:16

Hi, I'm Sue from the Salvesen Mindroom Research Center at the University of Edinburgh. Um, I'm recording another PsychologiCALL episode today. This is our little podcast, we're aiming to make a bit of evidence-based contribution to the conversations that people are having a lot at the moment about child and adolescent wellbeing and development and learning. And today I am very delighted to be talking to Courtenay Norbury, who is a professor at University College, London, and a visiting professor at University of Oslo, and Courtenay is also a speech and language therapist. And she's going to be talking to me about the SCALES study, which stands for the Surrey Communication and Language in Education Study. So hello, Courtenay, how are you today?

Courtenay: 1:04

Hello, Sue, I'm really good, thank you, how are you?

Sue: 1:07

I am not too shabby at all, thank you very much- I'm wearing a glittery top and there's some snow in my garden from last night.

Courtenay: 1:15

Sounds wonderful.

Sue: 1:17

Um, so tell me what are the kind of headline things that you've been discovering in the SCALES study?

Courtenay: 1:24

Okay, so I think one of the main findings is that language is incredibly stable. And what this means is that if we were to take a whole year group of children and give them a language test and then line them up in the rank order of the scores that they get on that test and then test them on the same test every year, that rank order pretty much doesn't change from the beginning of school, primary school, to the end of primary school. So that's quite striking, but that doesn't mean that children don't change. So in the SCALES sample we've demonstrated that actually all children increase their language knowledge over time. And the exciting, but also head-scratching bit for me is that the rate of language change seems to be similar across that distribution. And what that means is that even those children who had the most severe language deficits when they started school- and many of them have other developmental challenges as well- made as much language progress as their peers who were doing really well when they came into school. And this is really, to me, really exciting and in my view demonstrates that universal education is a pretty awesome intervention. But the downside, the challenge is that that means that any gaps that were there when they started school really persist all the way through, and in our sample it's about a two year gap between the most able and the ones that have the most challenges.

Sue: 3:00

Well, that's, that is fascinating because it definitely goes against I think what I would predict. Um, but before we dig into that result in a bit more detail perhaps we should just turn back time a little bit and you could tell us a bit about what motivated you to set up the SCALES study.

Courtenay: 3:19

You have to turn back time quite a lot, Sue[laughs] cause I've been working on SCALES for a decade now, can you believe that? Right, so when I started in this field as a speech and language therapist, a million years ago, we talked about specific language impairment and as a clinician I always found that really puzzling because when you see a child who has, has language impairment, it's rarely the only thing that kids, those kids find challenging. Um, and as I started my PhD and started to learn more about developmental processes it seemed to me quite unlikely that language would be the only affected system when a child was not developing as we might expect them to. So, but I had to be kind of wary of the fact that, you know, most of the kids that I would see were coming through a clinic. And so what we call co-morbidity or these co-occurring challenges that kids have, um, might be elevated because the more things you've got going on, the more likely you are to get to a clinic. So what I thought we really needed was to look at, um, language profiles in the general population. Um, and so that's, that's how SCALES was born. Uh, and also we didn't, we didn't have any UK prevalence data about language disorder and the existing prevalence data, um, been collected by the very wonderful Bruce Tomblin, but more than 20 years ago and in Iowa. So I really thought that it would be useful to know how many children were starting school in the UK with lower than expected levels of language, what other developmental challenges they had at the time, and then how those things play out over time and what impact that has on other aspects of development.

Sue: 5:14

And so, so tell us a bit about the method that you're using in SCALES. This is a longitudinal study- you're following up the same children over time, is that right?

Courtenay: 5:23

Yep, it is a, it is a longitudinal study- very longitudinal study. So what we did is we, um, we have very great partnership, uh, in Surrey county council. So they were very willing to, uh, let us do this and, and really helped us do it. We wouldn't have been able to do it without them. And what we did was we, we tried to get every state maintained school in Surrey that had a reception class to take part, and just over 60% of all of those schools did- so we had about 180 schools taking part in all.

Sue: 5:59

That's amazing.

Courtenay: 6:00

[laughs] What we did was we bought reception class teachers out of teaching for a day and made them sit down and do some online questionnaires for every child in the class for us. So, bless them, they are amazing people. And in these questionnaires, we asked about, uh, the child's language and communication, their behaviour...um, and then we have the early years foundation stage profile which is, um, early learning attainment goals. So we started this in, it was children who started a mainstream reception classroom in 2011 and we had screening data for over 7,000 children. Um, and then we took, uh, a subsample of that big group and we followed them up over time. So we started off with about 600 children. We saw them in year one, year three, year six and we tried to see them last year when they were in year eight, uh, but COVID then decided to make that particularly challenging for us. So we were only able to see about half of them. Uh, but we do have, um, data on their language, their reading, their problem-solving skills, their social skills, um, and more recently aspects of their mental health. So it's a really rich data set.

Sue: 7:24

And so for those follow- ups your- this isn't just teacher report now, this is more face-to-face work as well with the kids.

Courtenay: 7:32

Oh yeah it is, um, so we had a whole army of wonderful research assistants who would go into schools and they would assess children directly on standardised tests of language and cognitive ability. We had child questionnaires- they tell us about their experiences of school, we did experimental tasks on their recognition of emotion or their executive control skills, so a whole range of things. Um, yeah, very rich dataset.

Sue: 8:06

Yeah, it's amazing, it's completely amazing. Um, so I can imagine that the, I mean, the options, the things to explore in that are absolutely, you know, there are so many. But if we think about this, this, um, finding that you flagged at the beginning about sort of stability of language profile across development, right? Could you tell us a bit about how you analysed that stability, what, what kind of techniques you were using to, to chart that change or lack of change?

Courtenay: 8:38

It's, it's very complicated and I am eternally grateful that Andrew Pickles is a collaborator on the branch because he is possibly the world's greatest statistician. Um, so one of the reasons that it's complicated is because, uh, you know, we have the smaller sample of, of 500 or so kids that we've seen all the way through, but we want to use that sample to say something about the bigger population that they came from. Um, and there are statistical techniques that you can use to do this. Um, so one of the ways we started off was to use weights, and that takes account of our study design. So for example, in our study, um, teachers rate boys as having more language difficulties than girls, but we recruit, we brought into our smaller sample, equal numbers of boys and girls. So you can use a weight to kind of say, well, the boy data should count for more because there are more boys with this profile in the population.

Sue: 9:41

Right, right, right.

Courtenay: 9:41

Um, but this becomes trickier to use when you've got longitudinal data because as you go along you not only have to account for the initial study design but you also have to account for why people drop out of the study, because people always do drop out of the study. Um, and so that's, that's where Andrew has come in recently and he's been looking at some really cutting edge techniques that will look at variables that you have for the entire population, so our screening questionnaire, and then use those to predict what your missing data would look like. Um, and that allows you to just, uh, make use of the whole sample that you started off with. Um, so that's a really tricky statistical one. But I think one of the things that, um, has really become apparent to me over time is is the issues and challenges that we have with measurement. So, um, so for example, we have a study where, um, we want to know, um, how language influences attention skills and vice versa. So for language, we have a standardised test- it's very reliable, it's the same test, the same items at every point in time. But the attention measure is a teacher questionnaire, um, which kind of intrinsically has less reliability. And also you have different teachers at different time points. So you have a much higher stability estimate in language than you do in attention and, because of that, you've got more room to explain variation and attention because there is more variation than you do to explain any variation in language. So that, that has made interpretation really difficult. Uh, and it, it has made me think a lot harder about how we measure the things that we're interested in and what other factors can influence that measurement.

Sue: 11:50

That's such an important point. And of course even you weren't using a teacher questionnaire, you know, I've found this with studies, um, just where we have quite a wide age range of children involved, it's very hard to find an experimental task based measure of attention that is easy enough for say a five year old and hard enough for a, for a 10 year old, right? That is the same measure. You know, it's, it's just incredibly difficult.

Courtenay: 12:18

Absolutely. And we hit that wall with our work on emotion recognition because not only do you have to have something that basically means the same thing over time, but we have huge variation in the language and cognitive skills within the population, so you have to have something that, at age five, everyone can do because if you've got floor effects that also affects the interpretation. Um, so yeah. We, we have done, we, we've tried to be upfront about that and, uh, you know, journal editors have varying degrees of sympathy with that. But it's, it's been quite an eye-opener. And I think the other thing is that, you know, a lot of our experimental measures are designed to show group differences, not individual differences. And so when you then try to, uh, take an experimental measure and relate it to one of your measures of individual differences, doesn't always work. Um, and so that's quite tricky too. Uh, and that's just in the psychological field. Once you get onto education assessment there's many more challenges with that. So, measurement has become increasingly important to me and that's a surprise.

Sue: 13:33

Yeah, no, but I think it is. And I think this is one of the reasons why people maybe sometimes get impatient with how slowly research moves, but quite often you come up against new discoveries and questions, but before you can address them, you need new measures or, you know, more broadly validated measures. So one of the reasons why we are so, so slow, I'm afraid people out there who were impatient with research, we're doing our best!

Courtenay: 14:01

Absolutely.

Sue: 14:04

So I could talk to you about measurement for ages, but let's go back to the, to the original kind of headline finding that, um, children are staying broadly in the same rank order over time. But also, I guess we could think of it in terms of how far away they're standing from their neighbors, right? Those spaces are about the same as well. So this is, I find this very counter-intuitive because I think my assumptions about language and development is that if you are, um, you know, at a kind of language disadvantage early in your life with a small vocabulary perhaps, or, um, something like that, that's going to compound and actually increase the gap between you and your peers, you know, and you're going to fall further behind. Was that, was that what you expected as well? Am I being very naive and ignorant with that expectation?

Courtenay: 15:02

No no, um, well I think, I think that is a not unreasonable expectation and I think we we'd seen enough, uh, longitudinal data from other places to be prepared for the fact that those kids who didn't have lots of multiple challenges were probably going to have parallel rates of growth. But I really thought, you know, in our sample, we do have kids who have lots of things going on and so we know that those kids, certainly by year three, a lot of them are in different, um, educational provisions. They, they have trouble reading, they have difficulties with peers. So actually the language that they're exposed to becomes quite different to their peers. Um, so I really did think that, uh, we would see gaps getting wiser. Um, that's not necessarily the case to the end of, um, primary school, but we've had a little sneak peak at year eight and I would say that, certainly for some things, you can start to see that gap opening, uh, in secondary school. And that, that could be lots of things. So, um, it could be measurement, it could be those changes in the environment and that it just takes time for you to see the impact that, that has. It could also be that when you get to secondary school, the nature of the language that you need to keep pace is changing. So when you get to secondary school, we use much more complicated syntax or grammar. Words are more abstract and they might have more nuanced interpretations depending on the context. And, you know, social relationships are also a lot, a lot trickier at that age. So it could be that, um, you know, in primary school, your capacity is kind of enough to keep you going on that track but the nature of what you need to do when you get to secondary school just exceeds that capacity and that's when the gap opens up. So it will be really interesting, uh, when we're, when we've got time and headspace to look at that in more detail.

Sue: 17:18

Mmm, that is incredibly interesting. Um, and so what do you think are the sort of practical implications from what you've discovered so far? I mean, I'm sure there are, you know, there's a list as long as your arm- but what would you sort of want to highlight for listeners that you think is an interesting y'know action that people can take or lesson that people can take home?

Courtenay: 17:39

Yeah. So I love these questions because this is where I think"if I ruled the world, what would I do?" So I think one thing that I would really highlight is that school is a good thing that, um, you know, kids do learn, um, school provides a consistent language learning environment and I think that's part of the reason why you get such high rates of stability once kids go to school. Um, but clearly closing the gap is difficult. Uh, and that really makes me think about what should the purpose of intervention be? You know, often when we talk about interventions, certainly at schools, they talk about closing the gap and if you were to go to speech and language therapy, often outcome is measured on some standardised test, which is all about moving you closer to that, uh, typical range or the typical mean. Um, so I've started to wonder if, if that's really possible to do and really whether that should be the goal of intervention anyway. Um, and I kind of think about it, um, now like other physical characteristics. So like, height or weight, which are other skills that we know are genetically influenced, are distributed in the population, um, but they're subject to environmental influences. So if, if I, um, well somebody once described me as an"athletic teddy bear", Sue. I have a kind of predisposition to be a bit curvy. Um, if I wanted to, uh, you know, I can change that through, you know, an intensive environmental modification that involves eating differently and exercising a lot more, and that will have a positive impact- that will move me closer to a typical mean whatever that is and that might have some health benefits as well. But once I stop doing that, I just kind of revert to my typical trajectory, right? So if you want to make a change, you can't have a short, sharp period of intervention and expect that that will move you onto a completely different track. What you need to do is kind of sustain that environmental input over the longer term. Now, obviously that's hard. When I think about something like running I think"I hate running because it's hard", but I've found other things that I can do that have the same benefit, um, and, and, and are some things that I can sustain over a longer period of time. So when I think about language intervention I think about that. I think short-term interventions- they might have an immediate impact, but that impact wouldn't be sustained. We have to think about the kinds of, uh, learning opportunities that we can give kids more consistently over a longer period of time and also think about those workarounds. And so instead of thinking,"can I change the language trajectory?" I started thinking,"what kinds of language skills do children need to participate more fully in our society?" And so some of the things that we've been picking up on are the importance of language for, um, developing emotional understanding and emotion regulation. And we're thinking, you know, we would need to test it, but, you know, we can teach kids language, can we teach them that sort of language? And if we did that, would they be able to use it in a way that might attenuate some of the negative secondary consequences of having language disorder? So that's how I think about it now.

Sue: 21:29

I think that's such a great perspective that you bring and I think it chimes with something that I've been thinking about a lot as well, which is, you know, working a bit harder to accept the differences between people and that there is a normal distribution with people closer to the tail end. And our goal in life should not be to smoosh everyone as close as possible as we can get to the middle, you know?

Courtenay: 21:52

Yes, absolutely.

Sue: 21:54

Yeah, yeah. Well- yes.

Courtenay: 21:56

Yeah, I was going to say, it's just figuring out, you know, for those, those kids who do have lots of challenges, you know, we know that's associated with negative outcomes, so, you know, what, what kind of level of language with reduce those negative outcomes, um, and allow them to really meet their potential? So I think that's a really open question for the field and one where we need young people with language disorders and their families and the people that work with them all the time to kind of help us think that one through.

Sue: 22:29

Yeah, absolutely agree. Um, so Courtney, this has been fascinating. Um, before we, before we finish, um, I think there are probably some early career researchers and maybe some students listening and I wondered if you had any words of wisdom that you wanted to drop before we, before we wrap up?

Courtenay: 22:50

Um, so yeah, so I've been thinking about this a lot and I think there's two things that I've really learned from SCALES apart from all the rich things that I've learned about, uh, language disorder. And one is, uh, you know, if you really, if it's your passion and you really want to do it- persevere. So I wrote two grants, uh, for SCALES that were both rejected before we finally got the third one funded. Uh, and almost didn't write the third one because, you know, rejection is hard, I'd been working on it for years, I had a baby in the meantime...I thought, oh, I just, there's no point I don't want to put myself through it again. Um, but I did. And I'm so glad I did because you know, that time we got, we got lucky and it just yielded this amazing project. So stay strong and don't give up. And the other thing I would say is to really, um, collaborate with wonderful people. I, when I, when I was deciding at that stage of my career, what to do, um, there was a lot of, well, not a lot, but there was some pressure to think about things like an ERC grant, which is, you know, an individual award and I knew that nobody in their right mind would like give me, as an individual, a lot of money to do SCALES because it's just the kind of project you can't do on your own. Um, and so I went down a route where we had a team and we had, we had a multidisciplinary team of wonderful collaborators- some of whom are, are more senior, more experienced than me. Uh, and I've just learned so much from them. And then through that project, we bring junior people on and I learned an equal amount from them. Uh, and I, I just think the science is much better for having such a strong, rich collaboration. So you can have pressure to kind of go, go at your own on your own and get fellowships and all these kinds of things but good collaborative science, I think, reaps huge rewards in the end and in all kinds of different ways.

Sue: 25:01

Oh, that's such a lovely, such a lovely note to end on. I completely agree. Um, thank you so much for your time, Courtenay, it's been a huge pleasure to talk to you and to hear more about SCALES, which is a study I think is admired, you know, um, all over the world and quite rightly. Um, for anyone who's listening, you'll be able to find out more about Courtenay's work about the SCALES study by following the links that we'll put in the podcast description on Buzzsprout or on your podcast app. And thank you so much, Courtenay, and goodbye!

Courtenay: 25:34

Thank you, Sue, i's been a huge pleasure to be here. I really appreciate it.

Outro: 25:42

Okay, we did it! I thought that went quite smoothly.