Latent Memory Traces for Prospective Items in Visual Working Memory

Visual working memory (VWM) is a capacity-limited cognitive system that is utilized for enabling goal-directed actions. When sampling items for VWM storage, however, observers are often exposed to other items that are not selected for imminent action (hereafter: "prospective items"). Here, we asked whether such exposure leads to memory buildup of these prospective items, facilitating subsequent VWM encoding for imminent action. In a series of experiments, we addressed this question using a copying task, in which participants attempted to reproduce a model display by placing items in an adjacent empty grid. To investigate whether a memory is formed for prospective items, we swapped the position of unplaced items in the model and compared copying task performance to a condition in which items remained stable. The results show that, when prospective items remained stable, participants took less time inspecting the model when encoding these items later (compared to when they were swapped). This reduced inspection duration was not accompanied by a higher number of inspections or an increase in errors. We conclude that the memory system gradually builds up latent memory traces of items that are not selected for imminent action, thus increasing the efficiency of subsequent VWM encoding.