Are early interventions effective?
Early years interventions can seem a particularly powerful way to forestall developmental difficulties. The wide-ranging evidence that early cognitive and behavioural difficulties can predict lifelong outcomes[i],[ii] makes it seem obvious that if a child is struggling, intervening earlier is better. This has led to considerable interest in intervening within the first few years of a child’s life, and the temptation to seek out earlier indicators of children’s cognitive development and wellbeing.
However, there are several challenges with choosing effective early interventions. First, reliably identifying which children will require support is a substantial challenge. This is particularly evident in the case of language development. Children’s language is a rich area for research on early intervention, for several reasons: it provides a window onto learning at school entry, and weak language at school entry is a risk factor for poor educational, social and emotional outcomes in subsequent years. There is also a clear socio-economic gradient in children’s language abilities, in which children from lower socio-economic backgrounds tend to have weaker language skills than their peers before they start school.
(But is the story really so simple?)
Despite this, children’s language abilities are highly variable and volatile before they are 4-5 years old, which makes the early identification of children who may be in need of intervention non-trivial. This is demonstrated by several studies showing that whilst children’s early vocabulary around 2 years of age can predict their later vocabulary and reading skills at school entry, this predictive power is very small. Only about 10-20%[iii],[iv] of the variation in children’s abilities at school is typically predicted by their early language skills, which indicates that there are multiple other factors that shape children’s outcomes. This also suggests that finding a sufficiently sensitive marker of early difficulties is challenging because of how much a child’s abilities can shift and develop over time.
This relates to the second challenge: early interventions can struggle to have sustained impacts unless intervention is ongoing. A good example of this comes from a recent study by McGillion and colleagues (2017). The researchers were interested in whether a caregiver intervention to promote talking with their 11-month old child would lead to changes in both parenting approach and children’s language development. Caregivers from a range of socio-economic backgrounds were randomly assigned to one of two conditions: watching a short video about talking with their child, or a control video about dental hygiene. One month later the caregivers in the language video condition talked more with their children than those in the control video condition. This fed into vocabulary improvement in the low socio-economic group: children in the intervention condition had higher vocabularies at 15 and 18 months compared to children in the control condition. However, at 24 months these benefits had disappeared, and there was no effect of the intervention on children’s vocabulary.
These findings demonstrate several important points about early interventions. Interventions can have a positive impact: in this case a brief, low-intensity video intervention was able to positively change caregiver behaviour, and this may have helped gains in children’s vocabulary a few months later. However, these effects were not sustained over time: they had faded by the time children were 2 years old. This shows how critical longer-term follow-ups are in intervention studies to understand whether benefits are long lasting. Moreover, this result reminds us that without ongoing support it is difficult for early gains in one area of cognition to offset other challenges children might face. The promise of early interventions means there can be an assumption that they will permanently shift a child’s trajectory. In reality this is often not the case, and initial gains may often require ongoing support to have real long-term effects for children.
It is important to therefore strike a balance between the promises and limitations of early interventions. Whilst endeavouring to find the right areas to target is undoubtedly valuable, the challenge of finding reliable indicators of difficulties early in a child’s life might mean searching for stable predictors at later ages (e.g. from school entry) may be a more fruitful approach[v]. In addition, long-term follow-ups to interventions may be key to understanding the extent to which they are effective. The challenge of early interventions is that development is complex and shaped by multiple factors. Working within these constraints may help us better identify and help children in need of ongoing support.
This newest article was contributed by our beloved lab member Erin Hawkins. Erin’s research focuses on understanding the mechanisms and interventions of developmental difficulties in children.
[i] Caspi et al. (2016). Childhood forecast of a small segment of the population with large economic burden. Nature Human Behaviour, doi:10.1038/s41562-016-0005
[ii] The Allen Report (2011). Early Intervention: The Next Steps. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/284086/early-intervention-next-steps2.pdf
[iii] Duff, Reen, Plunkett, & Nation (2015). Do infant vocabulary skills predict school-age language and literacy outcomes? Journal of Child Psychology and Psychiatry, doi:10.1111/jcpp.12378.
[iv] McGillion, Pine, Herbert & Matthews. (2017). A randomised controlled trial to test the effect of promoting caregiver contingent talk on language development in infants from diverse socioeconomic status backgrounds. Journal of Child Psychology and Psychiatry, doi:10.1111/jcpp.12725
[v] Norbury, C. (2015). Editorial: Early intervention in response to language delays – is there a danger of putting too many eggs in the wrong basket? Journal of Child Psychology and Psychiatry, doi:10.1111/jcpp.12446
For further reading:
Succinct reviews of the evidence and cost effectiveness of different kinds of early years interventions, by the Education Endowment Foundation: https://educationendowmentfoundation.org.uk/evidence-summaries/early-years-toolkit
The Early Intervention Foundation has practical reports on the effectiveness of various interventions: http://www.eif.org.uk/publication/
This report provides a case study of the ‘London effect’ in attainment gaps: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/321969/London_Schools_-_FINAL.pdf