Working memory representations play a key role in controlling attention, making it possible to shift attention to task relevant objects. Visual working memory has a capacity of 3–4 objects, but recent studies suggest that only one representation can guide attention at a given moment. We directly tested this proposal by monitoring eye movements while observers searched for one or two different colors in arrays containing two or four different colors. First, we identified behavioral signatures of template use: When observers implemented a single color template, they sequentially searched many consecutive items of a color (long run lengths), and they exhibited a delay prior to switching gaze from one color to another (switch cost). In contrast, when searching two colors simultaneously, observers exhibited short run lengths and no switch costs, consistent with the simultaneous guidance of attention by the two cued colors. Thus, multiple working memory representations can guide attention concurrently.

Efficient visual search requires that attention is guided strategically to relevant objects, and most theories of visual search implement this function by means of a target template maintained in visual working memory (VWM). However, there is currently debate over the architecture of VWM-based attentional guidance. We contrasted a single-item-template hypothesis with a multiple-item-template hypothesis, which differ in their claims about structural limits on the interaction between VWM representations and perceptual selection. Recent evidence from van Moorselaar, Theeuwes, and Olivers (2014) indicated that memory-based capture during search—an index of VWM guidance—is not observed when memory set size is increased beyond a single item, suggesting that multiple items in VWM do not guide attention. In the present study, we maximized the overlap between multiple colors held in VWM and the colors of distractors in a search array. Reliable capture was observed when two colors were held in VWM and both colors were present as distractors, using both the original van Moorselaar et al. singleton-shape search task and a search task that required focal attention to array elements (gap location in outline square stimuli). In the latter task, memory-based capture was consistent with the simultaneous guidance of attention by multiple VWM representations.

Context Working memory deficits are considered a core feature of schizophrenia. Several recent integrative papers have offered mechanistic computational and neurobiological models of the origins of this cognitive deficit. Objective To test predictions of these models using a new experimental paradigm from the basic science literature that makes it possible to determine whether patients with schizophrenia show: 1) deficits in working memory storage capacity, 2) deficits in the precision of working memory representations, and 3) an amplification of these deficits as the retention interval increases. Design Case control design. All subjects performed a color working memory test where they were asked to recall 3 or 4 items after a 1 or 4 second delay. All subjects also received a standard measure of intelligence and the MATRICS battery. Setting A tertiary care research outpatient clinic. Patients A total of 31 clinically stable patients with a DSM IV diagnosis of schizophrenia or schizoaffective disorder and 26 healthy volunteers participated. The two groups were similar in age, gender, and ethnicity distributions. Main Outcome measures We examined two outcome measures: 1) the number of items stored in working memory, and 2) the precision of the working memory representations. Results Patients showed a clear reduction in the number of items stored in working memory. Patients did not differ from controls in the precision of their working memory representations. There was no evidence of delay-related amplification of impairment in either capacity or precision. Conclusions Patients do not show the type of imprecision or delay-dependent amplification of impairment that are predicted on the basis of current models of the neurobiology of the illness. The models need to be revised to account for a pure reduction in the number of items that patients are able to store in working memory.

Theories of attention and visual search explain how attention is guided toward objects with known target features. But can attention be directed away from objects with a feature known to be associated only with distractors? Most studies have found that the demand to maintain the to-be-avoided feature in visual working memory biases attention toward matching objects rather than away from them. In contrast, Arita, Carlisle, and Woodman (2012) claimed that attention can be configured to selectively avoid objects that match a cued distractor color, and they reported evidence that this type of negative cue generates search benefits. However, the colors of the search array items in Arita et al. were segregated by hemifield (e.g., blue items on the left, red on the right), which allowed for a strategy of translating the feature-cue information into a simple spatial template (e.g., avoid right, or attend left). In the present study, we replicated the negative cue benefit using the Arita et al. method (albeit within a subset of participants who reliably used the color cues to guide attention). Then, we eliminated the benefit by using search arrays that could not be grouped by hemifield. Our results suggest that feature-guided avoidance is implemented only indirectly, in this case by translating feature-cue information into a spatial template.