Event Working Memory Selectively Impairs Dynamic Tracking

To construct and understand the dynamic world, our cognitive system continuously segments the information stream of external environment into discrete events. Events have been suggested as the fundamental unit of our cognitive system in processing dynamic scene, and owns independent storage buffer in working memory (event working memory, EWM). So far, the research investigating interaction between EWM and attention is largely unclear. To explore this issue, we took dynamic tracking as the typical task consuming dynamic attention, and examined whether EWM load affects the load effect (i.e., the more targets or distractors in a task, the worse tracking performance) in dynamic tracking. Since two distinct types of dynamic tracking, multiple identity tracking and multiple object tracking, may enjoy different cognitive mechanism, we explored the impact of EWM load on the two tasks separately. First, we examined the impact of EWM load on multiple identity tracking, and found that the load effect of multiple identity tracking was higher with EWM load (Experiment 1), which was not due to the impact of EWM on binding (Experiment 2). Then we examined the impact of EWM load on multiple object tracking, and found that the load effect remained constant in the dual-task condition regardless of the manipulation of the target load (Experiment 3) or distractor load (Experiment 4) of tracking. Overall, the current study found that EWM selectively impairs dynamic tracking, suggesting that EWM and dynamic tracking share dynamic attention resource pool.