Dissertations, Theses, and Capstone Projects

Date of Degree

10-2014

Document Type

Dissertation

Degree Name

Ph.D.

Program

Speech-Language-Hearing Sciences

Advisor

Klara Marton

Subject Categories

Cognitive Psychology | Linguistics | Speech and Hearing Science | Speech Pathology and Audiology

Keywords

Dual task, Fluency, Speech monitoring, Stuttering, Working memory

Abstract

The present study tested the counterintuitive hypothesis that engaging cognitive resources in a secondary task while speaking could benefit aspects of speech production. Effects of dual task conditions on speech fluency, rate, and error patterns were examined in stuttering and fluent speakers based on specific predictions derived from three related theoretical frameworks. Twenty fluent adults and 19 adults with confirmed diagnoses of stuttering participated in the study. All participants completed two baseline tasks: (1) a continuous speaking task in which spontaneous speech was produced in response to given prompts; and (2) a working memory (WM) task involving manipulations of WM domain, WM load, and inter-stimulus interval (ISI). In the dual task portion of the experiment, participants simultaneously performed the speaking task with each unique combination of WM conditions. Resulting performance patterns were examined based on speech-related measures (fluency, rate, errors) and WM accuracy in each speaker group. Contrary to predicted outcomes, both groups showed comparable decrements in secondary task performance as well as comparable fluency benefits as a result of dual task conditions. This effect was specific to atypical forms of disfluency and was similar across all manipulations of the WM task. Changes in fluency were accompanied by reductions in speaking rate, but not by corresponding changes in overt speech errors. Overall, findings suggest that WM contributes to disfluencies regardless of stuttering status and that suppressing these resources enhances speech fluency, possibly by inducing more implicit or automatic modes of movement during speech production. Further research is needed to more precisely identify the cognitive mechanism involved in this effect, clarify the nature of this association, and determine whether and how these findings can inform clinical intervention.

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