Effects of a secondary mental task and additional auditory feedback on body movements and EEG

Previous studies have shown that additional cognitive load from a secondary task can adversely affect movement performance. However, how externally provided auditory pacing influences motor and neural responses under dual-task conditions remains unclear. This study employed a repeated-measures experimental design, studying eighteen young adults (Mean age 23.5 ± 4 years) who underwent three conditions: (1) foot tapping only (single task), (2) foot tapping and a mental task (dual task), and (3) foot tapping, mental task, and auditory pacing biofeedback (dual task + biofeedback). Ankle joint movements using Xsens IMU's (Inertial Motion Units) and brain activities using EEG (electroencephalography) were measured in these three conditions. Results showed that dual tasks significantly reduced (p < 0.01) the range of motion and increased (p < 0.05) the variability of ankle joint range of motion, suggesting a decline in foot tapping performance compared to the single-task condition. The decline was accompanied by significant increases (p < 0.05) in relative high-beta power in EEG, consistent with heightened cognitive-motor demand during dual-tasking. In the dual-task + biofeedback condition, kinematic measures returned to values statistically indistinguishable from the single-task condition and response times in the cognitive task were significantly reduced, without a loss of accuracy. The relative high-beta power was also significantly reduced, compared with the dual-task condition, which may reflect increased entrainment to external cues or a reduction in cognitive load. These results support the role of auditory pacing in facilitating movement performance under dual-tasking conditions, while highlighting the need for future studies to dissociate entrainment effects from changes in cognitive workload.