Motor learning cannot explain stuttering adaptation.

When persons who stutter (PWS) read a text repeatedly, there is a progressive reduction in stutter frequency over the course of three to five readings. Recently, this phenomenon has been attributed by some researchers to motor learning-the acquisition of relatively permanent motor skills that facilitate fluency through practice in producing words. The current study tested this explanation. 23 PWS read prose passages five times in succession. The number of 'new' and 'old' stutters during repeated readings (words stuttered in the current reading but spoken fluently in the previous reading and words stuttered also in the previous reading) were analyzed. If motor learning facilitated fluency during repeated readings in PWS, words read fluently in a reading should not be stuttered in a later reading in significant numbers. Contrary to this prediction, there was no statistical difference in the number of new words stuttered across five readings. A plausible alternative explanation, which requires further study to verify, is offered.