in experimental design

Abstract Responses are faster when the side of stimulus and response correspond than when they do not correspond, even if stimulus location is irrelevant to the task at hand: the correspondence, spatial compatibility eVect, or Simon eVect. Generally, it is assumed that an automatically gener-ated spatial code is responsible for this eVect, but the pre-cise mechanism underlying the formation of this code is still under dispute. Two major alternatives have been pro-posed: the referential-coding account, which can be subdi-vided into a static version and an attention-centered version, and the attention-shift account. These accounts hold clear-cut predictions for attentional cuing experiments. The former would assume a Simon eVect irrespective of attentional cuing in its static version, whereas the attention-centered version of the referential-coding account and the attention-shift account would predict a decreased Simon eVect on validly as opposed to invalidly cued trials. How-ever, results from previous studies are equivocal to the eVects of attentional cuing on the Simon eVect. We argue here that attentional cueing reliably modulates the Simon eVect if some crucial experimental conditions, mostly rele-vant for optimizing attentional allocation, are met. Further-more, we propose that the Simon eVect may be better understood within the perspective of supra-modal spatial attention, thereby providing an explanation for observed discrepancies in the literature