When Less Can Be More: Dual Task Effects on Speech Fluency

Minimizing cognitive resources while executing wellpracticed motor tasks has been shown to increase automaticity and enhance performance (e.g., Beilock, Carr, Macmahon, & Starkes, 2002). Based on this principle, we examined whether more fluent speech production could be induced through a dual task paradigm that engaged working memory (WM) while speech was produced. We also considered whether effects varied for speakers who differed in their habitual degree of attentional control during speech production. Twenty fluent adults and 19 adults who stutter performed (1) a baseline speaking task, (2) a baseline WM task with manipulations of domain, load, and inter-stimulus interval (ISI), and (3) a series of dual tasks in which the speaking task was combined with each unique set of WM conditions. Results indicated a fluency benefit under dual task conditions, which was specific to atypical forms of disfluency but comparable across speaker types and manipulations of the WM task. Findings suggest that WM is associated with atypical forms of disfluency and that suppressing these resources enhances speech fluency, although further research is needed to specify the cognitive mechanism involved in this effect and clarify the nature of this association.