Purpose: The study aims to explore whether finite verbal morphology is affected in children/adolescents with Down syndrome (DS), whether observed deficits in this domain are indicative of a delayed or deviant development, and whether they are due to phonetic/phonological problems or deficits in phonological short-term memory.
Method: An elicitation task on subject-verb agreement, a picture-naming task targeting stem-final consonants that also express verbal agreement, a nonword repetition task, and a test on grammar comprehension were conducted with 2 groups of monolingual German children: 32 children/adolescents with DS (chronological age M = 11;01 [years;months]) and a group of 16 typically developing children (chronological age M = 4;00) matched on nonverbal mental age.
Results: Analyses reveal that a substantial number of children/adolescents with DS are impaired in marking verbal agreement and fail to reach an acquisition criterion. The production of word-final consonants succeeds, however, when these consonants do not express verbal agreement. Performance with verbal agreement and nonword repetition are related.
Conclusions: Data indicate that a substantial number of children/adolescents with DS display a deficit in verbal agreement inflection that cannot be attributed to phonetic/phonological problems. The influence of phonological short-term memory on the acquisition of subject-verb agreement has to be further explored.