Effect of the Dual -Task Condition on the Spatiotemporal Index of the Lower Lip in Adults Who Stutter

Abstract

The purpose of this study was to examine the effect of attention tasks on articulatory stability in Kannada-speaking adults with and without stuttering. Ten adults who stutter and 10 adults who do not stutter were subjected to both single and dual attention tasks, and their influence was examined on stimuli type (real and non-word sequences) and syllable length conditions (3 and 8 syllable lengths). We measured the Spatiotemporal Index (STI) for lower lip (LL) articulatory movements using Articulograph AG501, a composite measure of spatial and temporal variability for repeated speech tokens. We also measured the behavioral accuracy of the repeated speech tokens across the groups, in addition to LL STI. Results revealed no significant main effect of attention tasks on articulatory stability across AWS and AWNS. However, stimulus type interacted with attention tasks and syllable length across the groups for articulatory stability, wherein real words with shorter syllable length were less variable than non-words with longer syllable length. Additionally, we observed significant main effects for both stimulus type and syllable lengths on the mean STI variability within and across groups. The attention tasks had an effect on behavioral accuracy of non-words, with single tasks demonstrating better overall accuracy than dual tasks, and adults who stutter demonstrating poorer accuracy compared to those who do not stutter. We outlined the effect of multiple variables controlling speech motor attributes in adults with stuttering, along with its clinical implications.