Early childhood is a critical period of language development. Yet less is known about how language growth relates to the development of phoneme awareness and cognitive flexibility during this period. To examine the longitudinal associations between growth in phonological awareness and cognitive flexibility from 4 to 5 years in relation to three patterns of child language development: early, intermediate and late. A sample of 439 four-year-old children were recruited and underwent repeated language, phonological awareness and cognitive flexibility testing to age 5. Children were classified into three language development groups based on their listening comprehension: early, intermediate and late. Group-based trajectory modelling was then used to examine the relations between cognitive flexibility and phonological awareness over time in relation to language outcome. Early language developers were characterized by higher levels and greater improvement in language and phonological awareness skills between 4 and 5 years. Late language developers exhibited slower growth in expressive language development (in addition to lower receptive language at age 4). Intermediate and late language developers showed steeper growth in cognitive flexibility over the study. Findings affirm the interconnected nature of phoneme awareness, cognitive and language skill development in early childhood. Results suggest the importance of targeting skills across literacy and executive functioning/regulatory domains for children with language difficulties. What is already known on the subject It is already known that language skills are related to self-regulation and phoneme awareness skills. However, it is also important to examine how different patterns of language growth are related to the timing and level of growth in self-regulation and phoneme awareness. Further, it is important to examine the relationship between language development and cognitive flexibility (one component of self-regulation) to understand this relationship more fully. What this paper adds to the existing knowledge This study is novel in its examination of the trajectory of language development and other key foundational literacy variables along with modelling the timing of development across the constructs included in the study. The findings have implications for optimizing the content and timing of approaches designed to enhance literacy development in children with language difficulties. What are the potential or actual clinical implications of this work? The findings suggest that interprofessional approaches across speech-language therapy, education and psychology are important for enhancing literacy outcomes of children with language difficulties. Results also provide support for language intervention approaches to be developed and trialled that target language, cognitive flexibility and phonological awareness in an integrated manner.
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