The removal of information from working memory

What happens to goal-relevant information in working memory after it is no longer needed? Here, we review evidence for a selective removal process that operates on outdated information to limit working memory load and hence facilitates the maintenance of goal-relevant information. Removal alters the representations of irrelevant content so as to reduce access to it, thereby improving access to the remaining relevant content and also facilitating the encoding of new information. Both behavioral and neural evidence support the existence of a removal process that is separate from forgetting due to decay or interference. We discuss the potential mechanisms involved in removal and characterize the time course and duration of the process. In doing so, we propose the existence of two forms of removal: one is temporary, and reversible, which modifies working memory content without impacting content-to-context bindings, and another is permanent, which unbinds the content from its context in working memory (without necessarily impacting long-term forgetting). Finally, we discuss limitations on removal and prescribe conditions for evaluating evidence for or against this process

Computational and behavioral investigations of the SOB-CS removal mechanism in working memory

The SOB-CS computational model of working memory explains findings from simple and complex span experiments. According to the model’s mechanism of interference by superposition, high similarity between memory items and subsequently processed distractors is beneficial because the more a distractor is similar to an item, the more they share similar units, leading to less distortion of the memory item. When time allows, SOB-CS removes interfering distractors from memory by unbinding them from their context. The combination of these two mechanisms leads to the prediction that when free time is long enough to remove the distractors entirely, similarity between items and distractors should no longer be beneficial to memory performance. The aim of our study was to test this prediction with humans and simulations. Experimental data disconfirmed the prediction. Simulations showed that SOB-CS overestimated the strength of removal which has to be much lower than expected to account for experimental data