Updating, fast and slow: Items, but not item-context bindings, are quickly updated into working memory as part of response selection

It is commonly held that attending to items facilitates their encoding into working memory (WM). This implies that the content of WM is updated with new input as a consequence of directing attention to it. On the other hand, abundant research shows that WM updating is rather slow and effortful, suggesting that shielding WM representation against incoming input, rather than its updating, is the default. To resolve this discrepancy, we suggest that while updating item-to-context associations is costly, updating a single item is fast and is automatically carried out as part of directing attention to items, for example as part of response selection. Participants performed a choice-RT task, in which stimuli appeared within frames, and needed to update their WM with the most recent red item that appeared in each frame. The need for updating was manipulated, so that some trials required updating and others did not. Experiment 1 (N=25) showed that updating was slower than not updating with a set-size of two items, that required item-context binding, but faster when the set-size only involved one item. Experiment 2 (N=28) replicated this finding. Experiment 3 (N=20) showed that the slower no-update RTs are due to the removal of erroneously updated information. In contrast to previous findings, these results suggest that updating can be effortless and obligatory.