Abstract
When two visual targets (T1 & T2) are presented in rapid succession, performance of T2 suffers up to 900 ms. One theory of this attentional blink (Raymond, Shapiro, & Arnell, 1992) propose that T1 and T2 compete for limited processing resources (Chun & Potter, 1995), and predict that prolonging processing time for T1 by increasing its perceptual difficulty will induce a larger blink. Several studies have tested this prediction without reaching a consistent answer. McLaughlin, Shore, & Klein (2001) found no effect of the exposure duration of T1 on the attentional blink. Christmann & Leuthold (2004) found that increasing the contrast of T1 decreased the attentional blink but Chua (2005) found the opposite effect. In the current study, we varied the perceptual difficulty of T1 in the two-target paradigm (Duncan, Ward, & Shapiro, 1994) both by changing the contrast and by changing the exposure duration. In the hard condition, T1 exposure duration was 10 ms while T1 contrast was adjusted individually to reach 50% correct T1 identification. In the long duration condition, T1 exposure duration was increased to reach approximately 90% correct T1 identification. In the high contrast condition, T1 exposure duration was the same as in the hard condition while T1 contrast was adjusted individually to reach the same performance on the T1 identification task as obtained in the long duration condition. Six observers completed 260 trials in each of the three conditions. We found a strong effect of T1–T2 latency on performance in the T2 identification task in all conditions, replicating the finding of an attentional blink. However, we found no difference in the attentional blink between conditions. We conclude that increasing the perceptual difficulty of T1 either by decreasing T1 contrast or T1 exposure duration is not sufficient for modulating the attentional blink.
This study was supported by the Danish Council for Strategic Research.