Real-time inflectional processing by children with specific language impairment: effects of phonetic substance

In this study, we examined the processing of low-phonetic-substance inflections (e.g., third-person-singular -s, past-tense -ed) versus a higher-phonetic-substance inflection (e.g., present-progressive -ing) by children with specific language impairment (SLI) in two types of receptive tasks. Twenty-one children with SLI (Age: 8 years;6 months), 21 chronological age matched (CA; Age: 8;7), and 21 receptive syntax matched (RS; Age: 6;8) children participated in a word-recognition reaction time (RT) task and an off-line task requiring grammaticality judgments. On the RT task, the children with SLI demonstrated RT sensitivity only to the presence of a higher-phonetic-substance inflection, unlike the CA and RS controls who displayed sensitivity to both higher-substance and low-substance inflections. On the grammaticality judgment task, the children with SLI performed more poorly than the CA controls only on sentences missing obligatory low-substance inflections (e.g., "Carl already jump over the fence"). The findings are discussed within the framework of the surface account, which predicts that children with SLI should have greater difficulty processing and making grammatical judgments about low-substance inflections compared to higher-substance inflections.