Counting fast or slow, aloud or silently? A comparison of adult stutterers and non-stutterers

This study assesses factors influencing the capacity to maintain a steady rhythm during explicit counting activities. There are three counting paces (count every 800, 1200, or 1600 ms) and three experimental conditions (count silently, aloud and aloud in the presence of someone). The study also assesses the effect of a speech disorder, namely stuttering, on this counting ability by comparing the performance of a group of adult stutterers (n = 21) to that of a group of adult non-stutterers (n = 24). For temporal variability, in addition to replicating the fact that counting more slowly leads to lower performance, the results show that there are benefits to expect when participants count aloud instead of silently. There is no main effect of group, but the interaction between the experimental condition, the counting pace, and the group is significant. Adult non-stutterers are better than adult stutterers in the silent and long time-interval conditions (1600 ms). The significantly higher variability at 1600 ms indicates a loss of efficiency in the capacity to keep time constant when counting is slow, and it is in this condition that stutterers will gain the most benefits from counting aloud instead of silently.