Capturing focused attention.

When attention is diffuse, as in a visual search task, an abrupt onset almost invariably succeeds in capturing attention. But if attention had been cued in advance to a different location, the same onset may then fail to capture attention (Theeuwes, 1991; Yantis and Jonides, 1990). In previous demonstrations, the onset appeared frequently. This may have diminished the onset's novelty, which in turn could have affected its potency in capturing attention. The question we asked was whether preserving the onset's novelty could enhance its capacity in capturing attention, even when attention had been prioritized elsewhere. As in Theeuwes's (1991) study, observers were cued to the target location with a 100%-predictive central arrow cue. The frequency with which visual transients were introduced was varied across experiments. When the onset stimulus appeared frequently (Experiment 1), it indeed failed to capture attention. But when its appearance was relatively infrequent (Experiment 2), capture effects were clearly observed. In Experiment 3, the target appeared in one location throughout the experiment. This would have improved target localization, but an infrequently appearing onset stimulus still successfully captured attention.