抄録
It is known that people with intellectual and developmental disorders (IDD) have more deficits in syntactic than other linguistic abilities. However, only a few studies on the syntactic development of people with IDD have been conducted in Japan. As a result, basic studies, accumulated data and the development of assessment methods have been deficient in Japan compared to other countries. This review compared international research findings with studies conducted in Japan. The results indicated that various factors affect the acquisition of syntactic knowledge, including the type of disability and the educational environment, which have not been sufficiently investigated. Based on the results, we have discussed the need to conduct future studies in Japan. It is suggested that future studies need to undertake the following tasks. (1) Developing scales for assessing language development to objectively and comprehensively evaluate syntactic development. (2) Investigating factors affecting syntactic development in people with IDD from perspectives other than the mental age (MA) and intelligence quotient (IQ), including the type of disability, life experience, and cognitive development, among others. (3) Investigate syntactic development in IDD people based on their stage of development, i.e., before or after acquiring grammar.
