DECRIPTION (provided by the applicant): Visual selective attention is a crucial means of compensating for our limited ability to process multiple stimuli at one time. Observers can bias their perception of the visual world, selecting certain elements of a scene for full analysis while leaving others aside. While significant progress has been made in describing the spatial and temporal parameters of this ability (i.e. when and where spatial selection is possible), there has been less progress in understanding exactly how spatial selection is accomplished. The broad goal of this proposal is to provide insight into the specific mechanisms that mediate the changes in visual processing that are observed during visual selection. The proposed research investigates a previously undiscovered component of attentional control that causes increased levels of distractor exclusion when interference from distractors is likely. Previous research has shown that when stimulus displays contain high levels of visual noise, then spatial selection effects are enlarged. The key insight in this proposal is that some of these increases in selection efficiency are a result of changes in top-down attentional control, rather than being entirely display-driven. The present research is designed to understand the cognitive and neural basis of this mechanism of endogenous distractor exclusion. In addition, our work will address the overall architecture of attentional control, by comparing the behavioral and neural signatures of two forms of attentional control: the endogenous suppression of visual noise, and the top-down suppression of response conflict. By enhancing our understanding of top-down selection in visuospatial and response-mapping paradigms, the proposed research will contribute towards the ultimate goal of creating a unified model of executive processing.