Passive sentence production in Japanese-speaking children with intellectual disabilities: The role of verb forms, case markers, and phonological memory.

This study investigated the roles of verb forms, case markers, and phonological memory in the production of passive sentences among Japanese-speaking children with intellectual disabilities (ID). The ID group included children with Down syndrome (DS), and those with autism spectrum disorder and intellectual disability, who were compared with typically developing children matched for mental age. Participants completed sentence elicitation and nonword repetition tasks. The results showed that accurate passive verb form production was significantly challenging in the ID group, and this difficulty was not associated with phonological memory. As for case markers, the dative case production in passive sentence was significantly associated with phonological memory in the DS group. These results suggest that difficulties with passive verb forms may reflect processes beyond phonological memory and may involve syntactic processing. They also indicate that verb forms and case markers may rely on different processing mechanisms in Japanese passives.