Laryngeal and manual reaction times of stuttering and nonstuttering adults.

This investigation compared the reaction times of thirteen stuttering and thirteen nonstuttering adults for forefinger button pressing, nonspeech vocal initiation, and speech-mode vocal initiation. The stutterers and nonstutterers were matched individually for age, sex, and handedness. The reaction-time stimulus in all response conditions was the offset of a 1000-Hz pure tone. Two of the experimental conditions required button pressing with the right and left forefingers. The remaining four responses required vocal-fold vibration. The nonspeech vocal activity consisted of inspiratory phonation and expiratory throat clearing. The speech-mode vocal activity required production of the isolated vowel and the word. The results demonstrated that stuttering and nonstuttering adults differed significantly only on tasks requiring speech phonation. These results are compared to previous reaction-time investigations and related to factors which may influence sensory-motor pathways prior to and during speech.