Communication Disorders Ph.D. Dissertations


Influence of Cognitive Interference on Speech

Date of Award


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)


Communication Disorders

First Advisor

Jason Whitfield (Committee Chair)

Second Advisor

Craig Zirbel (Other)

Third Advisor

Brent Archer (Committee Member)

Fourth Advisor

Adam Fullenkamp (Committee Member)

Fifth Advisor

Ronald Scherer (Committee Member)


Talkers with communication disorders may experience breakdowns in the forward flow of speech that lead to disfluencies, pauses, hesitations, and errors. These communication breakdowns may result from a variety of competing demands associated with cognitive-linguistic and speech motor demands. The purpose of the current study was to assess the effect of competing speech motor programs on speech movements using several verbal response time tasks. Thirty young adults completed several response time tasks including the traditional Classic Stroop and Response Priming paradigms, as well as a Primed Stroop task, which included features of both traditional paradigms. All speakers performed all tasks to allow performance comparisons across tasks. In the Classic Stroop task, participants named the ink colors of a written color word that either matched (Congruent) or did not match (Incongruent) the ink color. In the Response Priming Task, participants read written target color words aloud that were preceded by a quickly presented word that either matched (Congruent) and or did not match (Incongruent) the target word. The Primed Stroop task combined features of the Response Priming and Classic Stroop tasks. Performance was measured using acoustic, electromyographic, and kinematic methods to examine differences in speech selection, initiation, and implementation between tasks and conditions. Overall, Incongruent trials were associated with longer Acoustic Response Times and Longer pre-speech muscle activation compared to Congruent trials. Additionally, congruent trials that included a prime that matched the target response were associated with faster response times than incongruent trials. Lip and jaw kinematics were largely unaffected by Task and Condition manipulations. These data may suggest that speech selection and initiation time may be more affected by cognitive interference than lip and jaw movements associated with these short verbal responses. Results are discussed within the context of prior empirical work and models of speech motor control and lexical selection.