Motor practice effects and sensorimotor integration in adults who stutter: Evidence from visuomotor tracking performance

Purpose: The purpose of this study was to utilize a visuomotor tracking task, with both the jaw and hand, to add to the literature regarding non-speech motor practice and sensorimotor integration (outside of auditory-motor integration domain) in adults who do (PWS) and do not (PWNS) stutter. Method: Participants were 15 PWS (14 males, mean age. =. 27.0) and 15 PWNS (14 males, mean age. =. 27.2). Participants tracked both predictable and unpredictable moving targets separately with their jaw and their dominant hand, and accuracy was assessed by calculating phase and amplitude difference between the participant and the target. Motor practice effect was examined by comparing group performance over consecutive tracking trials of predictable conditions as well as within the first trial of same conditions. Results: Results showed that compared to PWNS, PWS were not significantly different in matching either the phase (timing) or the amplitude of the target in both jaw and hand tracking of predictable and unpredictable targets. Further, there were no significant between-group differences in motor practice effects for either jaw or hand tracking. Both groups showed improved tracking accuracy within and between the trials. Conclusion: Our findings revealed no statistically significant differences in non-speech motor practice effects and integration of sensorimotor feedback between PWS and PWNS, at least in the context of the visuomotor tracking tasks employed in the study. In general, both talker groups exhibited practice effects (i.e., increased accuracy over time) within and between tracking trials during both jaw and hand tracking. Implications for these results are discussed.Educational Objectives: The reader will be able to: (a) describe the importance of motor learning and sensory-motor integration for speech, (b) summarize past research on PWS's performance during speech and nonspeech motor tasks, and (c) describe the relation between different aspects of speech and non-speech motor control and stuttering.