Removal of Information from Working Memory: Time Course and Consequences

Working memory updating is the process that replaces outdated content in working memory by new content. This requires removing outdated information and encoding new information. It is still unclear whether removal and encoding run sequentially or simultaneously. We explored this question in three experiments investigating the time course of removal and encoding, and their consequences for the functioning of working memory. The updating task we used involved three phases: the memory, the processing, and the retrieval phase. Across four conditions we manipulated whether the processing phase involved encoding, removal, neither, or both (i.e., updating). In Experiment 1 and 2, processing time was self-paced, and we measured processing times in each condition. In Experiment 3, we measured accuracy as a function of available processing time. After the processing, participants were asked to recall the final item for each position in the retrieval phase. The results indicated that encoding and removal are concurrent processes during updating, because updating did not take longer than either of its component processes. Additionally, we analyzed the proportion of correct responses and of different error types with a memory measurement model to investigate the effects of encoding and removal for information held in working memory. The analysis revealed that removal involves unbinding the outdated information from its context. However, despite the weakened bindings of information to its initial context, the outdated information still remains activated in working memory. Other information held in working memory benefitted little from removal of outdated information.