Surface forms and grammatical functions: past tense and passive participle use by children with specific language impairment.

Children with specific language impairment (SLI) use past tense -ed in fewer obligatory contexts than younger normally developing children matched for mean length of utterance (MLU). In this study, the use of passive participle -ed (e.g., kissed in The frog got kissed by the kitty) as well as past tense -ed was examined in children with SLI, normally developing children matched for age (ND-A), and normally developing children matched for MLU (ND-MLU). The children with SLI used both past tense -ed and passive participle -ed in fewer obligatory contexts than bath the ND-A and the ND-MLU children. Only the children with SLI had greater difficulty with past tense -ed than with passive participle -ed. The pattern of findings indicates that the surface properties of -ed cannot adequately account for the past tense -ed difficulty shown by the children with SLI. However, the fact that the children with SLI were less consistant than the ND-MLU children in using passive participle -ed suggests that either the surface properties of -ed are responsible for a portion of the difficulty or these children have a separate, non-tense-related deficit in the area of verb morphology.