Involvement of the Central Cognitive Mechanism in Word Production in Adults Who Stutter.

Purpose: The study examined whether semantic and phonological encoding processes were capacity demanding, involving the central cognitive mechanism, in adults who do and do not stutter (AWS and NS) to better understand the role of cognitive demand in linguistic processing and stuttering. We asked (a) whether the two linguistic processes in AWS are capacity demanding, which can temporally disrupt the processing of a concurrent nonlinguistic task, and (b) whether AWS and NS show similar patterns of temporal disruption in the two processes.

Method: Twenty AWS and 20 matched NS participated in the study. We examined semantic interference and phonological facilitation effects, using the picture-word interference paradigm, under concurrent and sequential processing of a secondary, nonlinguistic task.

Results: Both AWS and NS showed statistically significant semantic interference and phonological facilitation effects, and both effects caused temporal disruption to the processing of a secondary task to the predicted extent.

Conclusions: The observed result patterns in both AWS and NS suggest that both semantic and phonological encoding processes are capacity demanding and can be vulnerable to concurrent processing demands. This finding on NS is inconsistent with the current literature on young, fluent adults and warrants further investigation.