{'fraction_non_alphanumeric': 0.023858921161825725, 'fraction_numerical': 0.0, 'mean_word_length': 5.433333333333334, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 1, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Language Development in Down Syndrome

This chapter is a review of research on language development in individuals with Down syndrome. The development of various aspects of language is described from infancy to adulthood, with a focus on gestures and prelinguistic communication, speech, vocabulary, syntax, and pragmatics. In each area, the profile of relative strengths and weaknesses is described, as well as the trajectory of development, and differences relative to other disorders, and the influence of other aspects of the phenotype of individuals with Down syndrome (e.g., memory impairments). Research is briefly reviewed on possible influences of the social and linguistic environments of individuals with Down syndrome on their language development. The chapter focuses on research on the learning of English as a first language; however, where possible, data from other languages and cultures is considered. Directions for future research are outlined.