Dynamic competition between bottom-up saliency and top-down goals in early visual cortex.

Task-irrelevant yet salient stimuli can elicit automatic, bottom-up attentional capture and compete with top-down, goal-directed processes for neural representation. However, the temporal dynamics underlying this competition, and how they influence early visual processing, remain poorly understood. Here, we combine electroencephalography with Rapid Invisible Frequency Tagging (RIFT) to non-invasively and simultaneously track early visual responses to target and distractor. Both target and distractor evoke stronger initial RIFT responses than nontarget, reflecting top-down and bottom-up attentional effects on early visual processing. Importantly, the presence of a distractor attenuates the initial RIFT response to the target, reflecting competition during the initial stages of visual processing. RIFT responses to the distractor eventually decrease below responses to the target and nontarget, representing active suppression of task-irrelevant stimuli. We show that the dynamic interplay between top-down control and bottom-up saliency directly impacts early visual responses, thereby illuminating a complete timeline of attentional competition in visual cortex.