Decoding the process of matching attended items to target templates during visual search

All major theories of visual attention posit a fundamental process wherein newly attended stimuli are systematically compared with target representations stored in memory to identify them as targets or reject them as distractors. In this study, we sought to test this proposal by decoding the electrophysiological brain activity as participants were cued to search for specific target objects in arrays. By strategically placing the target cues and the search elements at unique spatial locations, we were able to track when participants deployed external attention to select potential target items within the search array versus when they used internal attention to reactivate the representation of the sought-for target. We found evidence of the selection of the potential target object, followed by the reactivation of the target template held in memory. Further analyses demonstrated a correlation between the timing of target template reactivation and participants' behavioral reaction times, indicating that this reactivation process is closely linked to performing a detailed object comparison. Consequently, our study demonstrates how the electrophysiological brain activity provides a means to measure spotlights of attention as they shift between internal representations and the external environment, shedding light on the intricate mechanisms involved in the search for target objects.