Theoretically, substantial intertrial effects observed in pop-out search tasks would require that models of automatic, stimulus-driven visual selection are revised; that is, they would need to incorporate influences of other, organism-specific factors. However, rather than making priority computation “smarter,” it is also possible to assume that the PoP and DREs arise from later, post-selective stages. Such accounts were proposed for both the PoP (Huang, Holcombe, & Pashler,
2004; Huang & Pashler,
2005) and the DREs (Cohen & Magen,
1999; Mortier, Theeuwes, & Starreveld,
2005). According to post-selective accounts of the intertrial effects, visual selection is primarily stimulus-driven (i.e., feature discontinuity-driven) while the organism-specific factors, such as recent trial history, play a role only following the stage of visual selection. However, because the existence of post-selective mechanisms does not a priori exclude the possibility of preselective mechanisms sensitive to intertrial sequences, the most recent theoretical work has recognized the pre- versus post-selective dichotomy as being unsatisfactory. Rather, current models of both the PoP (Lamy, Yashar, & Ruderman,
2010; Yashar & Lamy,
2011) and DREs (Rangelov, Müller, & Zehetleitner,
2011a,
2011b,
2012; Zehetleitner, Rangelov, & Müller,
2012) postulate the existence of
multiple mechanisms sensitive to intertrial sequences. Some of these would be preselective, assuming that “smart” priority computation processes are possible to an extent (for a similar distinction between “dumb” and “smart” priority signals, see Bisley & Goldberg,
2010). Note, though, that multiple-mechanism accounts of PoP and DREs have, thus far, been developed independently, each addressing primarily one type of effect. Accordingly, exactly how the explanations of one and the other type of effect relate to each other remains an open issue. On the one hand, it is possible that the same mechanisms give rise to both PoP and DREs; on the other hand, it could be that the two types of effect have altogether different origins. Based on the results of the present study, a more detailed notion of the relationship between the mechanisms driving the PoP and DREs is put forward in the
Discussion.