Removal of information from working memory: A specific updating process

• We introduce a method for isolating a process unique to working memory updating.
• Removal of outdated information is an active working memory updating process.
• Removal speed can be measured reliably.
• Removal speed is independent of working memory capacity.

Previous research has claimed that working memory (WM) updating is one of three primary central executive processes, and the only one to reliably predict fluid intelligence. However, standard WM updating tasks confound updating requirements with generic WM functions. This article introduces a method for isolating a process unique to WM updating, namely the removal of no-longer relevant information. In a modified version of an established updating paradigm, to-be-updated items were cued before the new memoranda were presented. Overall, longer cue-target intervals—that is, longer time available for removal of outdated information—led to faster updating, suggesting that people can actively remove information from WM. Experiments 1 and 2 demonstrated that well-established effects of item repetition and similarity on updating RTs were diminished with longer cue-target interval, arguably because representational overlap between outdated and new information becomes less influential when outdated information can be removed prior to new encoding. Experiment 3 looked at individual differences, using the reduction of updating RTs to measure removal speed. Removal speed was measured reliably but was uncorrelated to WM capacity. We conclude that (1) removal of outdated information can be experimentally isolated and measured reliably, (2) removal speed is a unique, active WM updating ability, and (3) the view of WM updating as a core executive process that uniquely predicts fluid abilities is overstated.