On the time course of spatial cueing: Dissociating between a set for fast reorienting and a set for cue-target segregation

The present study tests whether two different manipulations leading to an earlier appearance of Inhibition of Return operate by setting the system in different ways. Whereas the use of a range of very long SOAs has been proposed to set the system for the early reorienting of attention (Cheal & Chastain, 2002), introducing a distractor at the location opposite the target seems to induce a set to represent the cue and the target as separated events instead of the same event (Lupiáñez et al., 1999, 2001). The effects of these two manipulations were directly compared within the context of a spatial stroop paradigm. Although both manipulations altered the time course of cueing effects, we report here a pattern of interesting dissociations: the distractor manipulation was unique to introduce a shift towards more negative cueing effect affecting generally all levels of SOA, including the shortest level of 100 ms. Secondly, the distractor manipulation, but not the range of SOAs one, was able to prevent the expected interaction between spatial stroop effects and cueing at the short SOA, typically found in previous experiments in the absence of a distractor (Funes et al., 2003, 2005). This pattern of dissociations strongly favors the hypothesis that these two attentional sets are different in nature.