In a visual search task, knowing features of distractors in advance leads to a more efficient visual search. Although previous studies suggested that the benefits of these negative cues rely on attentional control, it is unclear whether proactive or reactive control is involved. In this study, we analyzed the EEG data of participants performing a visual search task ( n = 14). Participants searched for a shape-defined target after receiving a positive cue (target color), negative cue (distractor color), or neutral cue (non-informative). To examine proactive control, we measured EEG after the cue onset but before visual search. Our time–frequency analysis revealed a higher power of theta oscillations over frontoparietal regions after the negative cues compared with the positive and neutral cues, as well as higher theta phase synchronization within the prefrontal region, demonstrating negative cues rely more heavily on proactive control compared with other cue types. To examine reactive control, we measured EEG after the search onset. We found a lateralization of posterior alpha power toward the target side in both positive and negative cues conditions, with a later lateralization observed after negative cues. Interestingly, we observed a significant relationship between the increase of proactive theta power after negative cues and the decrease of reactive alpha power after the search. This suggests the coordination of proactive and reactive mechanisms lead to the most efficient search.

The question whether target selection in visual search can be effectively controlled by simultaneous attentional templates for multiple features is still under dispute. We investigated whether multiple-color attentional guidance is possible when target colors remain constant and can thus be represented in long-term memory but not when they change frequently and have to be held in working memory. Participants searched for one, two, or three possible target colors that were specified by cue displays at the start of each trial. In constant-color blocks, the same colors remained task-relevant throughout. In variable-color blocks, target colors changed between trials. The contralateral delay activity (CDA) to cue displays increased in amplitude as a function of color memory load in variable-color blocks, which indicates that cued target colors were held in working memory. In constant-color blocks, the CDA was much smaller, suggesting that color representations were primarily stored in long-term memory. N2pc components to targets were measured as a marker of attentional target selection. Target N2pcs were attenuated and delayed during multiple-color search, demonstrating less efficient attentional deployment to color-defined target objects relative to single-color search. Importantly, these costs were the same in constant-color and variable-color blocks. These results demonstrate that attentional guidance by multiple-feature as compared with single-feature templates is less efficient both when target features remain constant and can be represented in long-term memory and when they change across trials and therefore have to be maintained in working memory.

Biased competition theory proposes that representations in working memory drive visual attention to select similar inputs. However, behavioral tests of this hypothesis have led to mixed results. These inconsistent findings could be due to the inability of behavioral measures to reliably detect the early, automatic effects on attentional deployment that the memory representations exert. Alternatively, executive mechanisms may govern how working memory representations influence attention based on higher-level goals. In the present study, we tested these hypotheses using the N2pc component of participants' event-related potentials to directly measure the early deployments of covert attention. Participants searched for a target in an array that sometimes contained a memory-matching distractor. In Experiments 1 to 3, we manipulated the difficulty of the target discrimination and the proximity of distractors, but consistently observed that covert attention was deployed to the search targets and not the memory-matching distractors. In Experiment 4, we showed that when participants' goal involved attending to memory-matching items, these items elicited a large and early N2pc. Our findings demonstrate that working memory representations alone are not sufficient to guide early deployments of visual attention to matching inputs and that goal-dependent executive control mediates the interactions between working memory representations and visual attention.