Attentional shift to the newer object in the successive and simultaneous distractors previewing search.

When some distractors (old items) appear before the other distractors and the target (new items) during an inefficient visual search task, the old items are effectively excluded from the search (preview benefit). Previous studies have shown that this preview benefit is observed when items are presented in two temporal stages, namely the initial and second displays. In this situation, new and old items are defined by a single time point (i.e., new items appearing), and the newness of the items is constant through the target search. However, in the real world, the newness of items is updated by the newer objects appearing, which requires more complex computations to detect relevant information among them. The present study examined whether previewing affects the attentional shift to a newer object if multiple new items appear successively. I used the modified preview-search paradigm, which contains three temporally separated displays, and examined what happens if the singleton target appears 200 ms after other distractors appear in the third display. This successive (search) condition was compared to the simultaneous (search) condition in which no distractors were presented in the initial display, and all distractors appeared simultaneously in the second display. The results showed that attentional shift to a newer object requires more time in the successive condition than in the simultaneous condition (Experiment 1). Moreover, the search cost for the newer target would not be induced by a mere difference in the onset timings (Experiment 2) and would occur when the duration of the initial distractors was short, and thus visual marking of the initial distractors might not occur maximally (Experiment 3). Therefore, previewing degrades attentional shift to a newer object when multiple new items appear successively.