Cognitive control of action naming in adults who stutter

Based on previous evidence that cognitive control of lexical selection in object (noun) naming operates differently in adults who stutter (AWS) versus typically-fluent adults (TFA), the aim was to investigate cognitive control of lexical selection in action (verb) naming in AWS.

12 AWS and 12 TFA named line drawings depicting actions using verbs. Half of the pictures had high-agreement action names and the other half low-agreement action names. Naming accuracy and reaction times (RT), and event-related potentials (ERPs) time-locked to picture onset, were compared between groups.

Naming RTs were slower for low- versus high-agreement trials, and the magnitude of this effect was larger in AWS versus TFA. Delta-plot analysis of naming RTs revealed that individual differences in selective inhibition were associated with the agreement effect on naming RTs in AWS but not TFA. Action naming elicited frontal-central N2 activity in both agreement conditions in TFA but not AWS. Additionally, a later, posterior P3b component was affected by agreement in TFA only. In AWS, low-agreement action naming elicited frontal P3a activation.

Results suggest that cognitive control of action name selection was qualitatively different between groups. In TFA, cognitive control of lexical selection in action naming involved nonselective inhibition, as well as more efficient working memory updating on high- versus low-agreement trials. In AWS, cognitive control of low-agreement action naming involved increased focal attention. Individual differences in selective inhibition may have moderated cognitive control of action naming in AWS.