Abstract
In visual search, the presence of a highly salient, singleton distractor interferes with selective processing of the target. This is partly due to the unwanted attentional shift to the salient stimulus, the so-called attentional capture effect, resulting in a measurable cost in performance. The stimulus–driven mechanisms mediating capture are antagonized by goal-driven mechanisms, which on the one hand maintain focus on the sought target while on the other attempt to suppress distractor processing. Lately, there has been growing interest toward the neural mechanisms supporting singleton capture, as well as those responsible for distractor suppression. Although neuroimaging data converge to indicate a key role of parietal and frontal-prefrontal regions in dealing with visual distractors, their respective role and any hemispheric specialization are still to be fully understood. Here we used transcranial magnetic stimulation (TMS) to shed light on the possible causal role of two key regions of the dorsal attention network in mediating and opposing attentional capture by a salient distractor. Participants were required to discriminate the direction of a target arrow while ignoring a task-irrelevant salient distractor, when present. Immediately after display presentation, TMS was delivered either to the Intraparietal Sulcus (IPS) or the Frontal Eye Field (FEF) on either side of the brain. Compared to a suitable sham condition, stimulation of the right FEF - but not of the left FEF – reliably reduced the cost engendered by the salient distractor, irrespective of the visual hemifield of target and distractor presentation. We found comparable but much weaker effects following right IPS stimulation. These findings provide direct, causal evidence that the right frontal cortex houses key mechanisms to limit interference from an irrelevant but attention-grabbing distractor, and further confirm previous evidence of right-hemisphere dominance at least in some forms of attention control.
Meeting abstract presented at VSS 2018