Movement planning and attentional control of visuospatial working memory: evidence from a grasp-to-place task

In this study, we have investigated the influence of available attentional resources on the dual-task costs of implementing a new action plan and the influence of movement planning on the transfer of information into visuospatial working memory. To approach these two questions, we have used a motor-memory dual-task design in which participants grasped a sphere and planned a placing movement toward a left or right target according to a directional arrow. Subsequently, they encoded a centrally presented memory stimulus (4 × 4 symbol matrix). While maintaining the information in working memory, a visual stay/change cue (presented on the left, center or right) either confirmed or reversed the planned movement direction. That is, participants had to execute either the prepared or the re-planned movement and finally reported the symbols at leisure. The results show that both, shifts of spatial attention required to process the incongruent stay/change cues and movement re-planning, constitute processing bottlenecks as they both reduced visuospatial working memory performance. Importantly, the spatial attention shifts and movement re-planning appeared to be independent of each other. Further, we found that the initial preparation of the placing movement influenced the report pattern of the central working memory stimulus. Preparing a leftward movement resulted in better memory performance for the left stimulus side, while the preparation of a rightward movement resulted in better memory performance for the right stimulus side. Hence, movement planning influenced the transfer of information into the capacity-limited working memory store. Therefore, our results suggest complex interactions in that the processes involved in movement planning, spatial attention and visuospatial working memory are functionally correlated but not linked in a mandatory fashion.