Selection of goal-directed information triggers removal of irrelevant information from working memory

This study investigated the triggers for removing irrelevant information from working memory. Based on the perspective that removal is a unique process of updating working memory (Ecker et al., 2010), we hypothesized that the removal process begins after selection of task-relevant information. To test this hypothesis, we employed a modified Sternberg task that reflects the time-course for the removal of information. In a standard procedure of this task, the removal process is thought to be completed in approximately 1,500 ms after directing relevant information. If selection induces removal, removal might not end within 1,500 ms when selection requires more time. To increase the time for selection, we created a circumstance with high interference. Experiment 1 showed that removal was incomplete within 2,000 ms after directing relevant information. Experiment 2 showed that removal could be completed given more time. These results support the hypothesis that the trigger for the removal process is the completion of selection. This is in consistent with recent frameworks concerning executive functions.