Abstract
INTRODUCTION: The primary aim was to determine whether the activation of target words unfolds differently in adults who stutter (AWS) versus typically-fluent adults (TFA) preparing to name pictures. A secondary aim was to explore the influence of conscious intention to speak on this process. METHOD: 18 AWS and 18 TFA completed a picture naming task in which pictures - named at a delay - were followed by auditory probe words that were identical, or unrelated, to the target picture labels. A subset of those participants (15 AWS and 15 TFA) completed a second task in which pictures - judged conceptually at a delay - were followed by auditory probe words that directly named the pictures or were unrelated. Event-related potentials (ERPs) were recorded from probe word onset in each task. It was predicted that the N400 ERP component - an index of lexical processing - would be attenuated to Identity versus Unrelated trials. Between-groups differences in lexical activation (if any) were predicted to result in between-groups differences in the amplitude, latency and/or scalp topography of N400 priming effects. RESULTS: N400 priming was detected in both tasks for both Groups. In the picture naming task, the N400 priming effect had a more broadly-distributed scalp topography in TFA versus AWS. No between-groups differences were detected in the N400 priming effect in the conceptual judgment task. CONCLUSIONS: A between-groups difference in the scalp topography of the N400 priming effect in the picture naming task points to a between-groups difference in intention-driven lexical access. Discussion considers how the top-down process of intention - if diminished among AWS - might impact lexical selection and speech motor control.