Comparison of Grammatical Morpheme Use in the Spontaneous Language of Children with Autism Spectrum Disorder and Developmental Language Disorder

Abstract

Objectives: This study investigated the characteristics of grammatical morpheme use in the spontaneous language of children with autism spectrum disorder (ASD) by comparing them with children with developmental language disorder (DLD), language age-matched (LA) typically developing children, and chronological age-matched (CA) typically developing children. Methods: Participants included 48 children aged 3 to 6 years: 12 children with ASD, 12 children with DLD, 12 LA children, and 12 CA children. Spontaneous language samples were collected using books and toys through an interaction-based procedure. Token frequency and type frequency of total grammatical morphemes, postpositions and their subcategories, and endings and their subcategories were analyzed from 50 utterances. Results: The ASD group showed significantly lower token and type frequencies of total grammatical morphemes than the CA group, but did not differ from the DLD or LA groups. For conjunctive postpositions, the ASD group produced significantly fewer tokens than the DLD and CA groups. For prefinal endings, a significant difference in token frequency was found only between the two typically developing groups. No significant group differences were found in the type frequency of conjunctive postpositions or prefinal endings. Conclusion: Except for some grammatical morphemes, children with ASD showed more limited grammatical morpheme use than their CA peers but demonstrated patterns similar to those of children with comparable language levels. These findings are discussed in terms of the characteristics of grammatical morpheme development in children with ASD.