Investigating differential practice effects on cued task-order coordination and coordination adjustment in dual tasks.

INTRODUCTION: Performing two overlapping tasks in dual-task situations requires task-order coordination, particularly when task order varies across trials. This coordination is associated with performance impairments on trials with different-order compared to same-order task sequences relative to the preceding trial (i.e., order switch costs). In addition, recent evidence suggests that task-order coordination can be adjusted based on contextual demands, as reflected in reduced order-switch costs following preceding different-order compared to same-order trials (i.e., switch adjustment effects). Practice effects provide an opportunity to disentangle these processes. However, previous research has largely relied on dual-task paradigms in which the task order is determined solely by the sequence of stimulus presentation, thereby limiting the role of top-down control via task-order cues. METHODS: The present study investigates task-order coordination and coordination adjustment in a dual-task paradigm in which the order of a visual digit task and an auditory tone task is indicated by explicit cues. Across four sessions, dual-task and single-task practice effects were compared. RESULTS: The results show reduced order-switch costs in Session 4 compared to Session 1, whereas no substantial changes were observed in the switch adjustment effects. DISCUSSION: These findings are interpreted as practice-related improvements in task-order coordination, whereas evidence for practice effects on coordination adjustment remains limited.