The effects of linguistic loading and autonomic arousal on speech motor coordination in adults and children
Though anecdotal reports link certain speech disorders to increases in autonomic arousal, little research has described the relationship between arousal and speech processes in typical speakers. Additionally, it is unclear how increases in arousal may interact with other cognitive-linguistic processes to affect speech motor control. The primary goal of this experiment was to examine the interactions between autonomic arousal, linguistic processing, and speech motor coordination in adults and children. Autonomic responses (heart rate, finger pulse volume, tonic skin conductance, and phasic skin conductance) were recorded simultaneously with upper and lower lip kinematic data during speech. The lip aperture variability (LA Coordination Index) across multiple repetitions of sentences that varied in length and syntactic complexity was calculated under low- and high-arousal conditions. High arousal conditions were elicited by performance of the Stroop color word task. Results indicated that children had significantly higher coordination indices across all speaking tasks, indicating more variable speech motor coordination. Increases in syntactic complexity and utterance length were associated with increases in the speech motor coordination variability in both speaker groups. There was a significant effect of Stroop task (associated with increases in arousal) on the speech motor coordination of both adults and children, indicating that high arousal levels can influence speech motor control in both adults and children.