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While the influence of context on long-term memory (LTM) is well documented, its effects on the interaction between working memory (WM) and LTM remain less understood. In this study, we explored these interactions using a delayed match-to-sample task, where participants (6 males, 16 females) encountered the same target object across six consecutive trials, facilitating the transition from WM to LTM. During half of these target repetitions, the background color changed. We measured the WM storage of the target using the contralateral delay activity in electroencephalography. Our results reveal that task-irrelevant context changes trigger the reactivation of long-term memories in WM. This reactivation may be attributed to content–context binding in WM and hippocampal pattern separation. [ABSTRACT FROM AUTHOR]

Evidence shows that visual working memory (VWM) is strongly served by attentional mechanisms, whereas other evidence shows that VWM representations readily survive when attention is being taken away. To reconcile these findings, we tested the hypothesis that directing attention away makes a memory representation vulnerable to interference from the test pattern, but only temporarily so. When given sufficient time, the robustness of VWM can be restored so that it is protected against test interference. In 5 experiments, participants remembered a single grating for a later memory test. In the crucial conditions, participants also performed a letter change detection task in between, during the delay period. Experiments 1-3 demonstrate and replicate the predicted effect: The intervening task had an adverse effect on memory performance, but only when the test display appeared immediately after the secondary task. At longer delays of 3.5 s, memory performance was on a par with conditions in which there was no intervening task. By varying the similarity of the test pattern to the memorized pattern, Experiments 4 and 5 further showed that performance suffered at early test intervals, unless the test item was dissimilar to the memory item. The results provide positive evidence for test interference, and demonstrates that the susceptibility to interference only occurs temporarily, as memory is restored when attention is allowed to return to the memorandum.

Recent empirical and theoretical work suggests that visual features such as color and orientation can be stored or retrieved independently in visual working memory (VWM), even in cases when they belong to the same object. Yet it remains unclear whether different feature dimensions have their own capacity limits, or whether they compete for shared but limited resources in VWM. In 3 experiments, participants memorized arrays of dual-feature objects, for which the number of feature values was fixed on one feature dimension and was varied on the other feature dimension. The results show that memory performance on the fixed dimension was not affected by the number of to-be-stored feature values on the other. These findings provide converging evidence that visual features can be encoded and stored separately in VWM if the task requires it, with each having its own capacity limit and little cross-dimensional interference.

Visual short-term memory (VSTM) performance is enhanced when the to-be-tested item is cued after encoding. This so-called retro-cue benefit is typically accompanied by a cost for the noncued items, suggesting that information is lost from VSTM upon presentation of a retrospective cue. Here we assessed whether noncued items can be restored to VSTM when made relevant again by a subsequent second cue. We presented either 1 or 2 consecutive retro-cues (80% valid) during the retention interval of a change-detection task. Relative to no cue, a valid cue increased VSTM capacity by 2 items, while an invalid cue decreased capacity by 2. Importantly, when a second, valid cue followed an invalid cue, capacity regained 2 items, so that performance was back on par. In addition, when the second cue was also invalid, there was no extra loss of information from VSTM, suggesting that those items that survived a first invalid cue, automatically also survived a second. We conclude that these results are in support of a very versatile VSTM system, in which memoranda adopt different representational states depending on whether they are deemed relevant now, in the future, or not at all. We discuss a neural model that is consistent with this conclusion.

For stable perception, we maintain mental representations of objects across space and time. What information is linked to such a representation? In this study, we extended our work showing that the spatiotemporal history of an object affects the way the object is attended the next time it is encountered. Observers conducted a visual search for a target among multiple distractors. Either the target location (Experiment 1) or the target feature (Experiment 2) could repeat from trial to trial. The entire visual search display was part of an object that could move in and out of view. Search was speeded when the target property repeated, but especially when the motion trajectory suggested that the same object had emerged. We show that this same-object benefit is tied to both the features and the spatial location of the target. It is most prominent for task-relevant features, but is weak to absent for task-irrelevant target features or for distractors carrying a salient feature. We conclude that attention uses an object-specific memory for relevant target information. Finally, we show that this object-specific memory is not affected by a change in the exterior appearance of the object, but depends on the spatiotemporal history (Experiment 3). (Contains 7 figures.)