Attentional Capture in Singleton-Detection and Feature-Search Modes

Six experiments were conducted to determine the circumstances under which an irrelevant singleton captures attention. Subjects searched for a target while ignoring a salient distractor that appeared at different stimulus onset asynchronies (SOAs) prior to each search display. Spatial congruency and interference effects were measured. The strategies available to find the target were controlled (only singleton-detection mode, only feature-search mode, or both search strategies available). An irrelevant abrupt onset captured attention in search for a color target, across SOAs, whatever strategies were available. In contrast, in search for a shape target, an irrelevant color singleton captured attention in the singleton-detection condition but delayed response at its location in the feature-search condition, across SOAs. When both strategies were available, capture was short lived (50- to 100-ms SOAs). The theoretical implications of these findings in relation to current views on attentional capture are discussed.