2016 年 25 巻 p. 3-16
In the present study, we review previous research on the development of theory of mind in deaf children and the acquisition of sign language by deaf children with autism spectrum disorder (ASD; children with D-ASD). Development of theory of mind is closely related to social interactions based on verbal communication. Therefore, deaf children who grew up in families with normal hearing perform poorly on the false-belief task, and exhibit tendencies resembling those of children with ASD. Moreover, difficulties in joint attention and perspective-taking, which are important elements of language acquisition, limit the acquisition of sign language by children with D-ASD regardless of differences in modality. It has been reported, however, that compared to deaf children with typical development (TD), children with high-functioning D-ASD did not exhibit marked differences in the comprehension and production of facial markers indicating the grammar and expressions of sign language, such as negation and question. Similarly, no differences were observed between children with high-functioning D-ASD and deaf children with TD on the Benton Facial Recognition Test. It was thought that when exposed to sign language, children with D-ASD pay more attention to facial expressions than do children with ASD who have normal hearing, and thereby develop a greater ability to recognize facial expressions. These findings offer suggestions regarding the nature of language acquisition and its associated cognitive mechanisms.