Atypical syntactic processing in individuals who stutter: evidence from event-related brain potentials and behavioral measures.

Syntactic processing was explored in individuals who stutter (IWS). Grammaticality judgments and event-related brain potentials (ERPs) were obtained while participants read sentences, half containing verb-agreement violations. Grammaticality judgments for an offline verb-agreement task did not differ between IWS and normal speakers (NS). However, judgment accuracy of IWS for the online task was lower than that of NS, particularly for verb-agreement violations that occurred in longer and more syntactically complex sentences. Further, while NS exhibited a classic P600 ERP response to verb-agreement violations, the P600s of IWS were reduced in amplitude and distribution. The behavioral and ERP results are consistent with the hypothesis that underlying mechanisms mediating language processing, including those related to postlexical syntactic reanalysis, may operate atypically in IWS even in the absence of speech production demands.