Selection of new objects by onset capture and visual marking.

Visual search is easier after looking at some distractors in advance because previewed distractors are excluded from the search (preview benefit). A dominant explanation for preview benefit is that it occurs because of the inhibition of old objects (visual marking). However, another view claims that preview benefit simply reflects automatic attentional orienting to new objects (onset capture). To address the question of whether visual marking plays any role in addition to onset capture, we compared the search performance for a target that always appeared as a new item ("marking" condition) with the performance for a target that appeared equally as a new or old item ("capture" condition). When items were presented at random positions in an invisible matrix, the slope in the "marking" condition was shallower than that in the "capture" condition, favoring the involvement of visual marking (Experiments 1 and 2). In contrast, no difference in slope was found among the search conditions regardless of changes in old items when items were arranged around the circumference of a circle (Experiment 3). These findings suggest that the contribution of visual marking depends on the configuration of search items; with complex displays, prioritizing selection for new objects is more effective if coupled with de-prioritizing de-selection for old objects.