Abstract
After attention has facilitated perception at a location, is it then reset by an active suppression mechanism or does it passively fade away? The present study investigated this issue by using ERP measures, which can track attention after the completion of a perceptual task without the addition of a secondary task. In Experiment 1, subjects searched for a target with a defined color at a peripheral location in arrays of three objects. We found that the target elicited an N2pc component (a measure of attentional deployment) followed by a Pd component (a measure of attentional suppression). In Experiment 2, the target was again defined by color, but now presented at the central location. When a distractor containing the target color was presented at a peripheral location, it also elicited N2pc followed by Pd. Experiment 3 confirmed that the Pd effect is associated with active suppression by showing its correlation with behavioral performance. In Experiment 4, a to-be-attended location (left or right) was cued on each trial, and the target was an object with a defined color at the attended location. We found P1 enhancement (a measure of spatial attention) followed by Pd for the target at the attended location, N2pc followed by Pd for a distractor containing the target color at the unattended location, and P1 enhancement followed by Pd for a non-target at the attended location. These results suggest that attentional enhancement is subsequently suppressed by active suppression mechanisms. This suppression may enable us to reset increased processing weights and disengage attention, leading to efficient preparation for upcoming information.