Task-specific and task-unspecific long term effects of cognitive-motormultitask training

人类的多任务处理能力是有限的。尽管如此，有充分的证据表明，通过特定的单任务训练，在各种认知和运动任务中的表现可以显著提高（SPP的可塑性观点），这种训练也可能转移到多任务情境中。此外，研究表明，与单任务训练相比，多任务训练甚至可能在练习任务和向未练习任务的转移中导致更大的绩效增量。在双重任务中，有三种可能的训练诱导的处理结构转换是可以想象的：a)减少至少一个涉及的任务的处理需求，b)单独的信息处理流的智能集成，以及c)增加处理资源的数量。我们将以运动-认知双任务训练为重点研究这些问题，即涉及足够复杂的连续运动任务的情况，如步行或其他姿势任务。这种类型的培训被广泛应用于老年人预防跌倒的背景下，并受到了具体的调查。它也受到了一些关注，因为它可能对认知表现有有益的影响。然而，这些训练效果背后的机制尚未得到最终确定。任何训练效果的关键因素是不同任务的处理流如何在练习中干扰和吸收资源。在第一个资助期，我们观察到“自动化”行走任务与更具挑战性的力跟踪任务在练习和转移任务中产生的表现水平上的不同效果，以及训练引起的处理结构的改变。在第二个资助期，我们将更深入地研究这些任务引起的处理结构。我们将使用探针-反应时间技术来揭示受试者在不同时刻参与处理每个任务的程度。我们将这项工作与进一步的训练研究结合起来，在这些研究中，受试者在几个星期内练习选定的运动-认知双重任务组合。基于这些研究中收集的数据，我们将回顾现有的解释性概念，这些概念可以归类为多任务处理过程中假设的固定限制或灵活限制处理。根据第一种方法，改进只能通过更有效地处理至少一个任务来解释，或者通过智能地集成处理流来解释。因此，长期训练的效果应该限制在至少涉及一种练习任务的情况下。灵活限制概念允许在某些情况下更有力地招募处理资源，因此看到长期增长的可能性。这种可塑性应该在更广泛的迁移情况下的性能收益中观察到。

Multi-tasking capacity of humans is limited. Nonetheless, there is ample evidence that perfor-mance in a variety of cognitive and motor tasks can significantly be improved (plasticity perspective of the SPP) by specific single-task training that might also transfer to multi-task situations. Moreo-ver, studies have demonstrated that multi-task training, compared to single-task training, may even lead to larger performance increments in the practiced tasks as well as in transfer to unpracticed tasks. Three possible training-induced transformations of the processing structure in dual tasks are conceivable: a) Reduction of processing demands of at least one of the tasks involved, b) smart integration of separate information processing streams, and c) increased quantity of processing resources.We will study these questions with a focus on motor-cognitive dual-task training, that is, situations in which a sufficiently complex continuous motor task is involved, like walking or other postural tasks. This type of training is widely applied in in the context of fall prevention in elderly and has been subject to specific investigations. It has also received some attention with respect to possible beneficial effects on cognitive performance. However, the mechanisms underlying these training effects have not been identified conclusively.A crucial factor for any resulting training effect is how processing streams of the different tasks in-terfere and recruit resources during practice. In the first funding period, we observed different effects for an "automatized" walking task compared to a more challenging force-tracking task at the level of the resulting performances in practiced and transfer tasks, and the training-induced altera-tions of the processing structure. In the second funding period, we will investigate the processing structure induced by these tasks in more depth. We will use a probe-reaction time technique to reveal, to which extent subjects are engaged in processing of each of the tasks at different moments in time. We combine this work with further training studies where subjects practice selected motor-cognitive dual-task combinations for several weeks. Based on the data collected in these studies, we will review existing explanatory concepts, which can be categorized as either assuming fixed-limit or flexible-limit processing during multitasking. According to the first, improvements can only be explained by more effective processing of at least one of the tasks, or by a smart integration of the processing streams. Accordingly, long-term training effects should be restricted to situations where at least one of the practiced tasks is involved. Flexible-limit concepts allow stronger recruitment of processing resources in certain contexts and, thus, see the possibility of long-term increases. This plasticity should then be observable in performance benefits in a broader range of transfer situations.