Abstract
A long debate centers on the extent to which salient, task irrelevant information captures spatial attention during visual search. This is in part because the majority of previous studies have used indirect behavioral measures as an assay of attentional capture, leading to several conflicting results and alternative interpretations. To overcome these limitations, we recorded single unit activity in frontal eye field (FEF), which provides a direct, moment-to-moment index of spatial attention, while simultaneously recording event-related potentials (ERPs) in response to salient distractor items. Critically, we found no evidence that neural correlates of spatial attention were directed to the salient distractor in either single units or ERPs. Instead, we observed a robust suppression of distractor-related activity in both measures. This suppression occurred early during visual processing in FEF units (~90ms), followed ~40ms later by suppression-related ERP responses at electrode sites over extrastriate visual cortex. This pattern of FEF suppression preceding suppression-related ERPs at posterior electrode sites is consistent with proposals that signals from FEF gate sensory processing in extrastriate cortex, and suggests that this gating occurs not only through target enhancement but also distractor suppression.
Meeting abstract presented at VSS 2016