Exploring the activation of target words in adults who stutter with and without conscious intention to speak: ERP evidence

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.