Attention modulates incidental memory encoding of human movements.

Attention has been shown to enhance the processing of task-relevant information while suppressing the processing of task-irrelevant information. However, it is less clear whether this attentional modulation exists when there is an intrinsic dependence between task-relevant and task-irrelevant information, such as the dependence of temporal processing on spatial information. In this study, we used complex whole-body movement sequences to investigate the extent to which the task-irrelevant spatial information (trajectory) is processed when only the temporal information (rhythm) is in focus. Moreover, we examined, if the task-irrelevant spatial information is "co-selected" with the target temporal information as predicted by the intrinsic spatiotemporal dependence, whether task-driven attention that is actively directed to spatial information provides extra benefits. Through a two-phase experiment (an incidental encoding phase followed by a surprise memory test phase), we found that the task-irrelevant spatial information was not only perceived but also encoded in memory, providing further evidence in support of a relatively automatic co-selection of spatial information in temporal processing. Nevertheless, we also found that movements whose trajectories were intentionally attended to during the encoding phase were recognized better in the test phase than those that were not, indicating a further modulation from attention on incidental memory encoding and information processing.