Searching for a color singleton among new items

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A difficult visual search can be enhanced when some distractors are presented beforehand, known as the preview benefit. This benefit is thought to arise from top-down inhibition of previous distractor locations, which narrows the search to new elements. Alternatively, it may stem from bottom-up attention capture due to the sudden appearance of new elements. This study aims to clarify the mechanisms behind the preview benefit through a series of experiments examining the time course of target and distractor processing using event-related brain potentials (ERPs). Results indicate that target selection, as shown by the N2pc component, is more efficient when half of the distractors are previewed. However, the presence of old distractors still interferes with the search process. Attention allocation to old distractor locations was assessed during the preview and after new elements appeared. Early ERP components in response to probes during the preview did not differ from neutral conditions, implying old distractors were passively processed. After new elements appeared, new distractors initially attracted more attention than old ones, but this difference diminished over time. These findings challenge the notion that old distractors are inhibited during the preview, supporting the idea of onset capture as the basis for the preview benefit.