A Meta-analysis on Speech Motor Abilities of People Who Stutter

Objectives: People who stutter (PWS) are suggested to stutter due to insufficient speech motor abilities. Speech motor abilities can be measured by reaction time, characteristics of fluent speech, and non-speech motor control. However there are some studies which have reported inconsistent results. Therefore the primary purpose of the current study is to provide a comprehensive perspective on whether there are differences in speech motor abilities between PWS and people who do not stutter (PWNS) by using meta-analysis. Moreover we tried to determine whether there are differences in the research areas and age groups. Methods: A total of four databases (two Korean and two English databases) were used in the current study for article search. A total of 51 articles (50 English, 1 Korean) met the inclusion/exclusion criteria and were analyzed in the current study. Results: There was a statistically significant difference in overall speech motor control between PWS and PWNS. In addition PWS in all age groups showed statistically significant differences from PWNS and there was no statistically significant difference across age groups. Furthermore, PWS showed statistically significant differences from PWNS in three research areas; reaction time, fluent speech, and motor control, whereas the differences across the three research areas were not statistically significant. Conclusion: The meta-analysis results of the current study showed that PWS showed insufficient speech motor abilities, and such insufficient speech motor abilities would be typical characteristics of stuttering. As such insufficient abilities are found across age groups and research areas a more comprehensive approach is needed in stuttering assessment and treatment.