The use and productivity of verb morphology in specific language impairment: an examination of Swedish

In an earlier study, we found that Swedish-speaking children with specific language impairment (SLI) differ from younger normally developing compatriots on only a subset of verb morphemes characteristically problematic for children with this type of disorder. In the present study, this finding was replicated, using a carefully devised set of tasks to elicit attempts at the target morphemes. The children with SLI used present copula forms and regular past-tense inflections with lower percentages than both younger and same-age control children. However, the children with SLI were as proficient as the younger controls in the use of present-tense inflections and irregular past forms. Given the pattern of the children's variability and their overregularization of the inflections, the findings could not be attributed to rote memorization of inflected forms. However, the children with SLI were relatively weak in their ability to apple the inflections to nonce verbs. We discuss the findings in terms of their implications for current characterizations of morphosyntactic deficits in SLI, in particular the agreement-deficit, extended optional-infinitive, and surface accounts.