Genetics and early language development: A UK study of twins

This chapter considers the intervention approaches for children who have language delay in the absence of other developmental disabilities. The primary focus of the discussion will be toddlers with late onset of language, and preschool and school-age children with specific language impairment (SLI). The term SLI refers to somewhat older children who demonstrate significant limitations in language skills without any clearly identifiable aetiology. In many cases, delays in language development are accompanied by cognitive, sensory or motor deficits. The chapter focuses initially on late talkers, followed by a discussion of children with SLI. Data for four of the linguistic variables were obtained from spontaneous language samples analysed using Systematic Analysis of Language Transcripts (SALT). These included: mean length of utterance in morphemes (MLU), total number of words, number of different words, and percentage of intelligible utterances. Vocabulary size was assessed using a parent report measure, the McArthur Communicative Development Inventory (CDI).