Transferability of cost reduction from dual-tasks to a triple-task – A comparison of new and trained participants

Dual-task paradigms have dominated multitasking research in recent decades. However, recent research has shown that adding a third task to a standard dual-task is not just an add-on (Stefani et al., accepted). Response times and error rates increased more than twofold for the triple-task compared to dual-tasks. It seems that task coordination plays a crucial role in multiple task processing. In the present study, we sought to narrow the gap between lab-based and real-world applications, as the prediction of current cognitive models is still restricted. In Experiment 1, we trained participants in a location-hand and pitch-voice dual-task for up to nine sessions. In another eight sessions, this was followed by a triple-task training (location-hand, pitch-voice, and color-feet) in Experiment 2. In addition, participants with no prior knowledge of dual- or triple-task also trained the triple-task in eight sessions. In E2, all single-tasks and all possible dual-task combinations were also trained. We could demonstrate that participants who had previously trained dual-tasks benefited from them in E2. However, they could not gain a significant advantage in the new third single-task (responding to color stimuli with their foot). In the last session, no difference in training status could be detected anymore. In general, the higher demands on the coordination of subtasks seem to have a much greater impact on response times than in dual-tasks, which is given little to no consideration in the current multitasking research.