自閉症のバイモーダルバイリンガル児における表現言語発達：10年間のケーススタディ

Children of Deaf adults (codas) acquire both a spoken language and a signed language from birth, making them bimodal bilinguals. While the language development of typically developing codas has been well studied, little is known about bimodal bilingual development in children with autism spectrum disorder (ASD).

This study presents the first longitudinal case study of expressive spoken and signed language in an autistic bimodal bilingual child, spanning ten years of development. The participant, a hearing child with Deaf parents, was exposed to both English and American Sign Language (ASL) from birth. Expressive language samples were analyzed at ages 4;11, 6;6, 9;11, and 14;11 for syntactic complexity, lexical diversity, modality use, and echolalia.

Results revealed a significant expressive language delay in both modalities, with no consistent advantage of one modality over the other. Despite lifelong exposure to ASL, the child exhibited similarly limited language development in both English and ASL, challenging assumptions that signed language may be inherently more accessible for autistic individuals. Although there were global delays in expressive language in both modalities, there was evidence of pragmatic strengths and sensitivity to the linguistic preferences of his conversation partners. Unique features of bimodal bilingualism in autism, including code-blending, whispering, and cross-modal echolalia, are described.

These findings highlight the need for further research into the developmental trajectories and communicative strategies of autistic bimodal bilingual children.