Accuracy and Variability of Isochronous Rhythmic Timing Across Motor Systems in Stuttering Versus Nonstuttering Individuals Ten adults who stutter and ten adults who do not stutter completed speech, orofacial nonspeech, and finger isochronous rhythmic timing tasks in a synchronization-continuation paradigm with auditory stimuli and with 450 ms, 650 ms, and 850 ms interstimulus onset intervals. Responses consisted of bilabial contact in the syllable /pa/ during ... Research Article
Research Article  |   February 01, 2003
Accuracy and Variability of Isochronous Rhythmic Timing Across Motor Systems in Stuttering Versus Nonstuttering Individuals
 
Author Affiliations & Notes
  • Ludo Max, PhD
    University of Connecticut, Storrs Haskins Laboratories, New Haven, CT
  • Elana M. Yudman
    North Rockland High School, Thiells, NY
  • Contact author: Ludo Max, PhD, University of Connecticut, Department of Communication Sciences, 850 Bolton Road, Unit 1085, Storrs, Connecticut 06269-1085.
    Contact author: Ludo Max, PhD, University of Connecticut, Department of Communication Sciences, 850 Bolton Road, Unit 1085, Storrs, Connecticut 06269-1085.×
  • Corresponding author: E-mail: ludo.max@uconn.edu
  • * Currently affiliated with Binghamton University, Binghamton, NY
    Currently affiliated with Binghamton University, Binghamton, NY×
Article Information
Speech, Voice & Prosodic Disorders / Fluency Disorders / Hearing & Speech Perception / Acoustics / Speech / Research Articles
Research Article   |   February 01, 2003
Accuracy and Variability of Isochronous Rhythmic Timing Across Motor Systems in Stuttering Versus Nonstuttering Individuals
Journal of Speech, Language, and Hearing Research, February 2003, Vol. 46, 146-163. doi:10.1044/1092-4388(2003/012)
History: Accepted July 31, 2002 , Received August 3, 2002
 
Journal of Speech, Language, and Hearing Research, February 2003, Vol. 46, 146-163. doi:10.1044/1092-4388(2003/012)
History: Accepted July 31, 2002; Received August 3, 2002
Web of Science® Times Cited: 30

Ten adults who stutter and ten adults who do not stutter completed speech, orofacial nonspeech, and finger isochronous rhythmic timing tasks in a synchronization-continuation paradigm with auditory stimuli and with 450 ms, 650 ms, and 850 ms interstimulus onset intervals. Responses consisted of bilabial contact in the syllable /pa/ during a speech task, bilabial contact in an orofacial nonspeech task, and thumb-index finger contact in a finger movement task. Effector movements were transduced, and time points associated with minima in the derived lip or finger aperture signals were automatically extracted. Multiple analyses of timing accuracy and variability were completed for both the synchronization and continuation phases, including decomposition of total timing variance into central clock and motor implementation variance according to the Wing-Kristofferson model. The combined results from descriptive comparisons, statistical significance testing, and effect size computations suggest that the stuttering and nonstuttering participants showed highly similar levels of both timing accuracy and timing variability. This was true (a) for all three motor tasks, b) at all movement rates, and (c) for synchronization as well as continuation movements. As one component of a systematic approach to investigating the role, if any, of timing difficulties in stuttering, these findings extend growing evidence that stuttering individuals do not differ from nonstuttering individuals in the ability to generate temporal movement patterns with a simple isochronous rhythm. We present some hypotheses about the implications that may follow from brain imaging and clinical neurological studies that have investigated the neural substrates recruited by this particular experimental task.

Acknowledgments
This work was funded, in part, by NIH Grant DC 03102. The authors gratefully acknowledge Vicki Neading, Sally Butcher, and Dave Scarbrough for help with subject recruiting, and Mike Sanders and John Alberton for assistance with instrumentation development and maintenance.
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