Information for researchers

Accurate, reliable language norms are critical for research on language development, for clinical practice and for policy making. For example, it is impossible to assess the impact of severe socio-economic disadvantage on language development without accurate descriptions of how much language, and of what type, we would normally expect UK children to produce and comprehend.

Since most language milestones occur in the first years of life, language norms for very young children are particularly important. However, they are also difficult to obtain because most language tests cannot be used with very young children. An effective solution is to use parent-completed Communicative Development Inventories (CDIs), in which parents fill in a wide-ranging checklist of their child’s communicative behaviours. CDIs and CDI language norms are used extensively in many countries in virtually every area of child language and child development research. However, no standardised CDIs and CDI language norms exist for UK English. This has had a substantial negative effect on UK research in child development, restricting the types of questions that research can answer and the scale of UK studies. Existing CDIs are sometimes used by UK researchers but many have no norms at all or are norms in the US and misinterpret the language level of British children (see Hamilton et al., 2000 for evidence that applying US norms to UK children will over-estimate the number of children with language delay in the UK). As a result, the use of CDIs in the UK, at best, is limited and, at worst, misinforms research, practice and policy making.

The aim of this project is to create the first standardised UK CDI- the UK CDI (Words & Gestures)- and to use the measure to establish population norms for UK children aged 8 to 18 months. The test and norms by age will be published as a commercial standardised test. In addition, data on a word-by-word basis will be made freely available worldwide via web-based UK Child Language Database. We will then use the data to publish two large-scale investigations. The first will assess the role of socio-economic factors in predicting language development in the UK; in particular, which factors put children most at risk for language delay and which factors may provide a level of protection. The second will establish whether vocabulary size and composition differs substantially across children learning different languages or learning different dialects of English, to inform cross-linguistic comparisons.

Our team have been given Level 1 authorisation by the CDI governing board, which gives us exclusive rights to publish a UK version. The project will have a substantial positive impact on UK research, particularly our ability to contribute to international debates about early language and cognitive development.