Abstract
Can people exert control over their attention allocations or is attention mainly driven by external factors? A positivity measured at posterior EEG sites contralateral to salient distractor singletons (distractor positivity, PD) has been linked to the active suppression of task-irrelevant stimuli during visual search. Given the extensive literature on cognitive control that ascribes the critical role of top-down control to (pre-)frontal brain areas, the PD likely reflects merely the consequence of attentional control (e.g., suppression at the level of the search-guiding priority map), rather than a cognitive control process proper. fMRI studies observing increases in frontal cortical activity when a distractor is present lack the temporal resolution to tell whether the frontal activity precedes the posterior activity, as would be expected if frontal areas exert control of priority signaling, or whether frontal activity is a mere by-product potentially reflecting retrospective evaluation of distractor handling. EEG, in contrast, provides the temporal resolution necessary to solve such questions. We were indeed able to extract a frontal EEG signal emerging around 200 ms after search-display onset whenever a salient distractor was present in two types of trial events: when a salient distractor did capture attention (i.e. when a misallocation had to be terminated) and when it was successfully suppressed before it could do so (i.e. when a misallocation was prevented). In both situations, the frontal component preceded the parietal PD component, lending support to the hypothesis that executive control processes residing in frontal brain areas cause the suppression of irrelevant distractor locations at the priority map, as reflected by the posterior PD. In any case, the early involvement of frontal areas indicates a critical role for executive control processes in distractor handling at an early stage of visual processing.
Meeting abstract presented at VSS 2018