Filtering performance in visual working memory is improved by reducing early spatial attention to the distractors.

We investigated the underlying processes that enable improving filtering irrelevant items from entering visual working memory (WM). To this end, participants performed a bilateral change-detection task in which either targets or targets along with distractors (i.e., the filtering condition) appeared in the memory array while ERPs were recorded. In the cue-present condition, we provided a spatial cue coupled with a temporal cue regarding where and when the distractors would appear. On some of the filtering trials, after the offset of the memory array, task-irrelevant probes were briefly flashed either at the locations of the targets or at the locations of the distractors. This enabled measuring whether reactivating the filtering settings resulted in reducing spatial attentional resources to the distractors, allocating additional spatial attentional resources to the targets, or both, as was measured by the P1/N1 amplitude. Results revealed that, relative to the cue-absent condition, in the cue-present condition the P1/N1 amplitude was reduced for probes at the distractors and was similar for probes at the targets. In addition, the reduction in the P1/N1 amplitude was accompanied by a reduced filtering cost in accuracy performance in the cue-present condition relative to the cue-absent condition. These findings suggest that reactivating the distractor filtering settings improved filtering performance in visual WM by reducing the allocation of spatial attention to the distractors already at early processing stages, and not by allocating additional spatial attentional resources to the targets.

Gestalt grouping cues can improve filtering performance in visual working memory.

As part of filtering irrelevant information from entering visual working memory (VWM) and selecting only the relevant information for further processing the system should first tag the pieces of information as relevant or irrelevant. We manipulated difficulty of tagging items as relevant or irrelevant by applying perceptual grouping cues to investigate if it can improve filtering performance in VWM. Participants performed a change-detection task with three targets, six targets, or three targets and three distractors (filtering condition) in the memory display, and were asked to remember the colors (Experiments 1-2) or the orientations (Experiments 3-5) of the targets and ignore the distractors. In the filtering conditions, either the targets (Experiments 1, 3, and 4) or the distractors (Experiments 2 and 5) formed an illusory object (a Kanizsa triangle), appeared in a triangle-like configuration (grouping by proximity), or appeared at random positions (non-grouping). Grouping the targets improved filtering performance relative to non-grouping. Moreover, the illusory object cue further improved filtering performance beyond a proximity cue, but only when the cue was compatible with the task. When the distractors were grouped, the proximity cue improved filtering performance, and the illusory object cue, despite being a potent grouping cue, failed to improve filtering performance when it was compatible with the task. We suggest that the grouping cues advanced tagging of the grouped items. Yet, when the grouping cue strongly enhanced processing of the distractors, the tagging failed, such that the preliminary process of estimating incoming items led to full processing of the grouped items.

Correction to: Gestalt grouping cues can improve filtering performance in visual working memory.

The original version of this article unfortunately contained a mistake.

Dissociating between the N2pc and attentional shifting: An attentional blink study.

The N2pc is routinely used as an electrophysiological index of attentional shifting. Its absence is thus taken as evidence that no shift of attention occurred. We provide evidence in contrast to this notion using a variant of the attentional blink (AB) paradigm. Two target letters, embedded in two streams of distractor letters and defined by their color, were separated by either 300 or 800 ms. The second target was preceded by a distractor frame of the same color (cue). As expected, identification of the second target was poorer at the short than at the long lag (the AB effect). The AB did not affect attentional capture by the cue, but suppressed and delayed the N2pc associated with it. This result suggests that the N2pc does not reflect attentional shifting. Instead, we conclude that the N2pc indexes the transient enhancement that occurs at the spatial focus of attention and promotes high-level processing such as identification. This conclusion calls for a reinterpretation of findings from the attentional capture literature that relied on the N2pc as an index of attentional shifting. Our results also inform contemporary models of the AB.

Compensation mechanisms that improve distractor filtering are short-lived.

We investigated possible compensation mechanisms for improving filtering of distractors from entering visual Working Memory (WM). Participants preformed a change-detection task in which three targets, six targets, or three targets along with three distractors (the filtering trial) were randomly presented. In six experiments, we tried to reduce the filtering cost, calculated as the difference in accuracy between the three targets and the filtering condition, by either cueing the possible locations of the distractors using placeholders (that could be either fixed throughout the experiment or change every trial; i.e., location cue), or by providing the location cue coupled with a warning cue singling the upcoming filtering trial. Results revealed that the filtering cost was not reduced by a fixed location cue (Experiment 1 and Experiment 5). However, the fixed location cue coupled with a warning cue (Experiment 2 and Experiment 5) or a location cue that changed positions every trial (Experiment 6), were sufficient to reduce the filtering cost. Additionally, longer preparation interval for filtering trials did not further reduce the filtering cost (Experiment 3). We argue these findings support that in the context of visual WM, spatial filtering settings can only be held for a limited amount of time. Thus, these filtering settings must be reactivated in order to be effective and to reduce the filtering cost.

How low can you go? Changing the resolution of novel complex objects in visual working memory according to task demands.

In three experiments we manipulated the resolution of novel complex objects in visual working memory (WM) by changing task demands. Previous studies that investigated the trade-off between quantity and resolution in visual WM yielded mixed results for simple familiar stimuli. We used the contralateral delay activity as an electrophysiological marker to directly track the deployment of visual WM resources while participants preformed a change-detection task. Across three experiments we presented the same novel complex items but changed the task demands. In Experiment 1 we induced a medium resolution task by using change trials in which a random polygon changed to a different type of polygon and replicated previous findings showing that novel complex objects are represented with higher resolution relative to simple familiar objects. In Experiment 2 we induced a low resolution task that required distinguishing between polygons and other types of stimulus categories, but we failed in finding a corresponding decrease in the resolution of the represented item. Finally, in Experiment 3 we induced a high resolution task that required discriminating between highly similar polygons with somewhat different contours. This time, we observed an increase in the item's resolution. Our findings indicate that the resolution for novel complex objects can be increased but not decreased according to task demands, suggesting that minimal resolution is required in order to maintain these items in visual WM. These findings support studies claiming that capacity and resolution in visual WM reflect different mechanisms.