Stimulus material for the manuscript: "Adjustments of balance control during cognitive dual tasking: Evidence from event-related force-plate analysis"

Cognitive-motor interference refers to the interaction between cognitive and motor processes occurring at the same time. Recently, balance control parameters while standing on a force plate were analysed using an event-related approach while participants performed a Simon task. Resolving response conflict in incongruent trials reduced balance adjustments prior to manual response execution, suggesting a bottleneck for concurrent cognitive and balance control. In the present study, we combined this approach with a cognitive dual task which comprised a visual-vocal short-term memory task with a delayed vocal response and an auditory-manual reaction time (RT) task. This hybrid psychological refractory period (PRP) paradigm created a functional processing bottleneck during memory consolidation in the visual-vocal short-term memory task. To examine how this cognitive bottleneck influences balance control, 48 participants per experiment stood quietly on a force plate, and balance control was quantified as moment variability (mNm) in 100 ms sliding windows. We varied the stimulus-onset asynchrony (SOA: 100 vs. 1,000 ms) between the targets (Experiment 1) and task load (report vs. ignore the visual object; Experiment 2). As expected, auditory-manual RTs increased at short SOA, showing dual-task interference that persisted in ignore trials, consistent with task-set inertia. Force-plate data were analysed using cluster permutation analysis to identify time-specific effects. Participants were less likely to adjust balance during cognitive task processing and more likely after task completion, independent of the presence of a cognitive bottleneck. These findings suggest that balance control flexibly delays or advances balance adjustments based on cognitive demands, thereby reducing cognitive-motor interference.

Cognitive-motor interference refers to the interaction between cognitive and motor processes occurring at the same time. Recently, balance control parameters while standing on a force plate were analysed using an event-related approach while participants performed a Simon task. Resolving response conflict in incongruent trials reduced balance adjustments prior to manual response execution, suggesting a bottleneck for concurrent cognitive and balance control. In the present study, we combined this approach with a cognitive dual task which comprised a visual-vocal short-term memory task with a delayed vocal response and an auditory-manual reaction time (RT) task. This hybrid psychological refractory period (PRP) paradigm created a functional processing bottleneck during memory consolidation in the visual-vocal short-term memory task. To examine how this cognitive bottleneck influences balance control, 48 participants per experiment stood quietly on a force plate, and balance control was quantified as moment variability (mNm) in 100 ms sliding windows. We varied the stimulus-onset asynchrony (SOA: 100 vs. 1,000 ms) between the targets (Experiment 1) and task load (report vs. ignore the visual object; Experiment 2). As expected, auditory-manual RTs increased at short SOA, showing dual-task interference that persisted in ignore trials, consistent with task-set inertia. Force-plate data were analysed using cluster permutation analysis to identify time-specific effects. Participants were less likely to adjust balance during cognitive task processing and more likely after task completion, independent of the presence of a cognitive bottleneck. These findings suggest that balance control flexibly delays or advances balance adjustments based on cognitive demands, thereby reducing cognitive-motor interference.