Early and late selection modulate competition for representation: Evidence from the N2pc in a multiple frame procedure

In this study, both bottom-up and top-down influences on processes of visual attention deployment are tested by examining the interaction between the similarity of a salient distractor to a salient target and the physical distance separating attended items in the visual field. Distractor-target similarity was varied both on a semantic and a physical level. Additionally, across experiments, the similarity of the salient items could vary in form, color, or both. Three experiments identified interactive relationships between these factors on the amplitude and the latency of N2pc, an ERP associated to the deployment of visuospatial attention. Results show the influence of both early form-based selection and late identification-based selection processes on the N2pc. Furthermore, selection processes appear to be dependent on the spatial proximity of the attended items, suggesting that some processes may operate on a local spatial scale.