Investigating mechanisms of suppression in preschool children with specific language impairment.

PURPOSE: This study investigated 2 suppression mechanisms--(a) resistance to distracter interference and (b) inhibition of a prepotent response--in preschool children with specific language impairment (SLI) and their typically developing peers. METHOD: Twenty-two preschool children with SLI and 22 typically developing controls participated in this study. The resistance to distracter interference task involved suppressing distracters (nonverbal auditory, linguistic, and visual) that were external and irrelevant to the task goal. Inhibition was assessed using a stop-signal paradigm to evaluate the ability to suppress a prepotent, conflicting response. RESULTS: The children with SLI exhibited decreased resistance to distracter interference regardless of distracter modality and poor inhibitory control relative to their typically developing peers. CONCLUSION: These results identify suppression weaknesses in preschool-age children with SLI. Specifically, children with this disorder exhibited difficulty suppressing both irrelevant and contradictory information.