title: Evidence that a motor timing deficit is a factor in the development of stuttering.
abstract: OBJECTIVE
  To determine whether young children who stutter have a basic motor timing and/or a coordination deficit.
  
  
  METHODS
  Between-hands coordination and variability of rhythmic motor timing were assessed in 17 children who stutter (4-6 years of age) and 13 age-matched controls. Children clapped in rhythm with a metronome with a 600-ms interbeat interval and then attempted to continue to match this target rate for 32 unpaced claps.
  
  
  RESULTS
  Children who stutter did not significantly differ from children who were typically developing on mean clapping rate or number of usable trials produced; however, they produced remarkably higher variability levels of interclap interval. Of particular interest was the bimodal distribution of the stuttering children on clapping variability. One subgroup of children who stutter clustered within the normal range, but 60% of the children who stutter exhibited timing variability that was greater than the poorest performing nonstuttering child. Children who stutter were not more variable in measures of coordination between the 2 hands (mean and median phase difference between hands).
  
  
  CONCLUSIONS
  We infer that there is a subgroup of young stuttering children who exhibit a nonspeech motor timing deficit, and we discuss this result as it pertains to recovery or persistence of stuttering.
authors.affiliation: Department of Speech, Language, and Hearing Sciences, Purdue University, 1353 Heavilon Hall, 500 Oval Drive, West Lafayette, IN 47907-2038, USA.
authors.forename: Lindsey
authors.initials: L
authors.lastname: Olander
authors.forename: Anne
authors.initials: A
authors.lastname: Smith
authors.forename: Howard N
authors.initials: HN
authors.lastname: Zelaznik
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D006225:Hand / Q000502:physiology; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D010507:Periodicity; D013342:Stuttering / Q000209:etiology*; D013997:Time Factors