Effects of concurrent motor, linguistic, or cognitive tasks on speech motor performance.

This study examined the influence of 3 different types of concurrent tasks on speech motor performance. The goal was to uncover potential differences in speech movements relating to the nature of the secondary task. Twenty young adults repeated sentences either with or without simultaneous distractor activities. These distractions included a motor task (putting together washers, nuts, and bolts), a linguistic task (generating verbs from nouns), and a cognitive task (performing mental arithmetic). Lip movement data collected during the experimental conditions revealed decreases in displacement and velocity during the motor task. The linguistic and cognitive tasks were associated with increased spatiotemporal variability and increases in the strength of the negative correlations between upper and lower lip displacements. These findings show that distractor tasks during speech can have a significant influence on several labial kinematic measures. This suggests that the balance of neural resources allocated to different aspects of human communication may shift according to situational demands.