Impact of asymmetric cognitive load and task priority manipulation on dual-task interference.

Rather than viewing dual-task interference solely as a fixed structural limitation, recent strategic models suggest that it should be dynamically managed through active goal-protection strategies, such as task shielding. This study investigated how strategic control recruitment interacts with overall cognitive load and explicit task-priority instructions in asymmetric task environments. Twenty-four healthy adults performed two distinct paradigms: a low cognitive load paradigm (simple reaction task + go/no-go task) and a high cognitive load paradigm (simple arrow task + flanker arrow task), each composed of low- and high-difficulty components. The task priority was manipulated toward the lower-difficulty component, the higher-difficulty component, or equally between the two. Instructional compliance was objectively verified through a validation analysis of reaction times in 1-second lead time trials. The results revealed that, in the high cognitive load paradigm, explicit priority instructions significantly redistributed dual-task interference. Prioritizing one task component successfully reduces its performance decrement at the expense of the non-prioritized task. Conversely, the low-cognitive-load paradigm exhibited no significant differences in dual-task interference across priority conditions. These findings suggest that the implementation of strategic control, such as "task shielding," is affected by cognitive load. Although many dual task combinations exist, task shielding and task priority shifts may emerge in paradigms that impose a sufficiently high cognitive load to necessitate proactive goal protection.