Speech Kinematics and Perioral Muscle Activity Are Influenced by Stroop Effects

The current project aimed to examine the effects of two experimental cognitive-linguistic paradigms, the Stroop task and a primed Stroop task, on speech kinematics and perioral muscle activation.

Acoustic, kinematic, and surface electromyographic data were collected from the verbal responses of 30 young adult healthy control participants in choice response, classic Stroop, and primed Stroop tasks. The classic and primed Stroop tasks included congruent and incongruent trials. Across all three tasks, the set of possible responses was limited to the same three possible color words (red, green, and black) to facilitate performance comparisons between tasks.

Trials with ink-word incongruence in the Stroop tasks resulted in significantly higher muscle activation in the upper lip during response selection. In addition, a prime word within the Stroop task resulted in more spatial variation in lip + jaw movements for the spoken responses. These results were accompanied by the expected longer response times for incongruent trials in both classic and primed Stroop tasks.

These findings may suggest that more central cognitive-linguistic interference processes may lead to inefficiencies in more peripheral speech motor control. Future research should investigate the pattern of these effects in older adults with and without motor speech disorders for research and clinical applications.