Courtenay Norbury - “Narrowing the gap: what longitudinal studies tell us about intervention needs?”

Previous contributions to this blog have helpfully outlined the key factors to look for when making decisions about currently available interventions. In this post, I want to look at the bigger picture, and consider how basic research can inform our approach to intervention more generally.

Longitudinal studies repeatedly indicate that language is a highly stable trait, a bit like height. There is considerable variation in the early years (and again in adolescence) at the rate at which children experience growth, but the shortest children in the class in Year 1 tend to be the shortest young people leaving school, despite the fact that they’ve grown a fair bit over the years. Language appears to behave in much the same way; children with lower levels of language competence at school entry tend to have persistently low language scores relative to their peers throughout their academic careers, with a 2-3 year gap between children at the top and bottom of the language distribution.


This does not mean that children with language deficits cannot improve. In fact they do, and their rate of language growth is parallel to more able peers.  The challenge is that in order to narrow the gap with peers, children with language disorder need to acquire language at a faster rate than peers. Current evidence seems to suggest that faster than expected growth is rare at best. Our best intervention studies show us that it is possible to increase language competencies relative to a control group, but only with intensive, targeted input over a consistent period. Even then, the differences between groups are modest, and the treatment advantage tends to diminish over time.

While this may seem a gloomy picture, I think it tells us a number of important truths that could influence practice. The first is that ‘cure’ is probably an unrealistic goal of therapy, and thus change on a standardised test should not be our metric of success. In fact, for some children establishing a viable means of communication may be more important than increasing language capacity per se (for example, in our work, 1% of children in mainstream reception classrooms had minimal levels of expressive language). Second, the level of language a child has at school entry appears to set the learning trajectory. To my mind this suggests that intensive effort in nursery is needed to increase language capacity and give vulnerable children the best possible chance at classroom success. Nevertheless, some children will always be at the bottom of the language distribution, and thus there is a need to ensure that these children can access specialist services later in development. I’m not necessarily recommending on-going intensive intervention, but it is worth considering potential periods where additional support might be critical (transition to secondary school, for example).

If rate of language learning isn’t malleable, it is also worth considering the broader impacts that modest improvements in language may yield. Many oral language interventions also measure literacy outcomes, with varying degrees of success (depending in part on the age of the children). Few studies though have measured changes in social, emotional, and behavioural functioning as part of a language intervention. Inclusion of such outcome measures could provide crucial evidence of how these skills are related and the potential to reduce negative outcomes associated with language disorder.

In sum, all evidence indicates that there is no quick fix for language disorder and yet our models of intervention still largely advocate short term ‘packages of care’. Of course funding constraints shape practice, but if this is the limit of what we can offer, we need to carefully consider what we can realistically hope to achieve in those few sessions. We almost certainly can teach a new skill or strategy, and it should be one that makes a functional difference to a child’s life. But if we are serious about narrowing the gap, the status quo will not suffice. We can and should, therefore, use research evidence to start thinking about novel approaches to meeting the needs of children with persistent language learning needs.

Courtenay Norbury is professor of Developmental Disorders of Language and Communication at Psychology and Language Sciences, University College London; and Director of the Literacy, Language and Communication (LiLaC) Lab @lilacCourt

Written by Courtenay Norbury at 00:00