Regular and irregular inflection in down syndrome - New evidence from German.

The study aims to explore whether regular inflectional morphology is affected in children/adolescents with Down syndrome (DS). German past participle forms were elicited for ten regular and ten irregular inflected verbs as well as for five novel verbs. Data were collected from a group of 21 monolingual German children and adolescents with DS (chronological age M = 11;03 years) and a group of 21 typically developing monolingual German children (chronological age M = 4;03 years) matched in chronological age to the nonverbal mental age of the DS group (mental age DS group M = 4;05 years). Data analysis indicated that eight children/adolescents with DS displayed a deficit in acquiring the regular participle marker -t and in applying it as default inflection in German participle formation. In contrast, a group of 13 individuals with DS performed similar to the typically developing control children. They had successfully acquired the regular participle affix -t and readily applied it as default inflection to produce participles for irregular verbs and novel verbs. The data indicate that the acquisition of regular inflectional morphology is not outside the scope of individuals with DS and succeeded in many affected individuals. However, a substantial number of individuals with DS displayed a selective deficit with regular default inflection. The occurrence of a selective deficit with regular default inflection in individuals with DS supports dualistic views to inflection, according to which two different cognitive components are involved in regular and irregular inflection that can be selectively affected in language disorders.