Subject-verb agreement in Down Syndrome: morphosyntactic analysis and cross-linguistic predictions on universal defaults

Abstract

While studies on English individuals with Down syndrome (DS) report impaired performance with the production of  subject-verb (S/V) agreement, Schaner-Wolles (2004) shows close to ceiling performance with the production of S/V agreement for German indi­viduals with DS. This study reports on findings from the production of S/V agreement of  Cypriot Greek adults diagnosed with DS and offers preliminary predictions with the purpose of disambiguating whether individuals with DS present a cross-linguistic impairment. The production of inflectional person and number marking was examined with sixteen Cypriot Greek individuals with DS and seventeen typically developing children, through nine sponta­neous and controlled elicitation tasks. The morphosyntactic analysis reveals close to ceiling performance with 98.5% accuracy for person and 99% accuracy for number. Results revealed a clear systematicity in selecting the default value for each inflectional feature: the 3^rd value for person and the singular value for number. Considering results from seven languages, it is predicted that the underlying coping strategy, whether it surfaces as an optional infinitive or a default feature value, is the same; namely, the use of a default form.