Working memory updating for free items and for item-to-context bindings: When attention is enough and when gating is needed

A well-supported working memory (WM) model holds that a "gate" separates the content of WM from information that does not need to be maintained or manipulated. Previous research suggests that switching between opening and closing this gate incurs a response-time cost, reflecting controlled cognitive effort. However, the exact nature of this cost remains debated. Some studies find that closing the gate is more costly than opening it, while in other studies these costs are comparable. Using an intertrial interval manipulation in the reference-back paradigm, we show that the larger cost of gate-closing is not an intrinsic feature of WM control, but is instead influenced by the automatic retention and removal of stimulus- and response-related information in WM. This finding indicates that WM is automatically but transiently updated with information for which attention-consuming processes such as response selection take place, challenging the prevailing view that WM updating is always effortful and controlled. Crucially, our findings reveal that updating individual items occurs rapidly and automatically when a single item is maintained. In contrast, updating bindings between items and their context is a slower, effortful process that requires gating. These results reconcile conflicting views regarding the nature of working memory encoding and updating.