Two papers published by CEN member Chloe Marshall and her colleagues at City University of London and UCL’s Deafness Cognition and Language Research Centre stress the importance of language for deaf children’s cognitive development. Deaf children are at risk of having delayed Executive Function (EF) development. It is well established that EFs play a critical role in children’s academic success and social and emotional wellbeing, and that they are closely associated with language skills. A long-standing debate in the research literature concerns whether language supports the development of EFs, or whether EFs support language development.

Marshall and her colleagues argue that deafness, a sensory impairment that negatively impacts children’s ability to take up language from the input, offers a unique way of testing the developmental relationship between language and EF. In a paper just published in the leading journal Child Development, they show that deaf children perform more poorly than hearing children on EF and vocabulary tasks, and that vocabulary level mediates EF performance (but not vice versa). In other words, deaf children’s poor EF can be explained by their low vocabulary levels, whereas their poor vocabulary cannot be explained by difficulties with EF tasks.

In an earlier paper published last year in Frontiers in Psychology, Marshall and her colleagues showed that poor working memory (an important component of EF) is not an inevitable consequence of deafness; deaf children who are native signers (i.e. grow up from birth in a home with parents who use a sign language) have comparable performance on working memory tasks to hearing children, but both those groups perform better than deaf children who are non-native signers.

Taken together, these studies suggest that growing up in an environment that offers a rich and accessible language input can protect deaf children from delayed EF development.