AGE AND TASK COMPLEXITY VARIABLES IN MOTOR-PERFORMANCE OF STUTTERING AND NONSTUTTERING CHILDREN

This paper is the first in a series of studies that explores the performance of young stutterers and nonstutterers on vocal and manual tasks of three levels of complexity in a simple reaction-time paradigm. Special attention was given to the selection of 40 subjects. Severity ratings were cited for stuttering subjects; they were matched with control subjects for gender, age, race, and school placement. An examiner screening sought to eliminate subjects with other known speech or language disorders. Stutterers had significantly slower reaction times (RTs) than nonstutterers. Changes in vocal and manual RTs followed a parallel course of improvement with age for both groups. Differences between performances of stutterers and nonstutterers increased with task complexity. Variability of performance of stutterers on manual tasks was not affected by task complexity; in contrast, variability of performance was significantly greater for stutterers under six on the most complex vocal tasks.