Comprehension of active, passive, and causative sentences by Japanese-speaking children with intellectual disabilities and typical development.

This study aimed to identify the comprehension strategies employed for active, passive, and causative sentences and the involvement of phonological memory, which is a subsystem of working memory, in the comprehension skills of Japanese-speaking children with intellectual disability (ID) compared to those with typical development (TD). The participants were 29 children with ID and 18 children with TD who were matched according to mental and vocabulary ages and phonological memory scores. A picture selection method was employed as a sentence comprehension task. The stimulus sentences were grouped into four patterns of word order: subject (S) - object (O) - verb (V), OSV, SV, and OV. For example, in active sentences, the subject and object are assigned to agent and patient, respectively. The results indicated that children in both groups made comprehension errors for sentences that lacked information regarding the agent and sentences in which the two-noun sequence inverts the typical agent - patient or instructor - instructed order. Phonological memory's involvement in sentence comprehension varied according to the combination of participant groups, sentence types, and patterns. The results suggest that both children with ID and TD relied on agent bias, whereby children consider the first noun to denote the actor and a word order strategy of interpreting a sequence of two noun phrases followed by the transitive verb as agent - patient - act. Furthermore, phonological memory underpins understanding of the relationships among arguments, particularly in the case of sentences for which agent bias or word order strategy may result in misinterpretation.