Visual working memory in action: Planning for multiple potential actions alongside multi-item visual encoding and retention

Visual working memory allows us to use past visual information to guide upcoming future behavior, serving as a bridge between perception and action. Previous research into visual working memory has classically concentrated on the (neural) mechanisms of encoding and retention of visual information. Yet, in our daily lives, we often rely on visual representations in memory to prepare for and guide potential future actions. Recent studies have demonstrated that, when retaining a single visual item in working memory, planning for the required manual action starts during the memory delay. We asked whether and how multiple potential actions are planned alongside the encoding and retention of multiple visual items during working memory. Human participants performed a visual working memory task with a delayed orientation-reproduction report (of one item), and a memory load manipulation (one/two/four items). Using scalp EEG, we measured 15-25Hz beta activity in central electrodes contralateral to the required response hand – a canonical neural marker of action planning. We show an attenuation of beta activity not only in load one (with high certainty about the prospective action), but also in load two (with two potential prospective actions), compared to load four (with low certainty about the prospective action). Action planning in load two occurs regardless of whether the two potential actions require a similar and dissimilar manual response. Moreover, the degree of beta attenuation during the memory delay in both load one and load two is predictive of the speed of ensuing memory-guided action. These results indicate that multiple potential actions are planned alongside the encoding and retention of multiple visual items in working memory. They bring the concept of parallel action planning to the domain of multi-item visual working memory, and highlight how visual working memory and action planning jointly help us prepare for the potential future.