Are there anisotropies in covert and overt visual orienting?

Abstract

Two recent studies suggest that Inhibition of Return (IOR) varies in magnitude as a function of target location for overt orienting tasks but not covert orienting tasks. Unfortunately, methodological differences between these studies prevent a direct comparison of their results. Thus the aim of the current study was to replicate and extend the results of these two studies within a single experiment while controlling for methodological differences. Participants (N=37) were assigned to a cue-target or a target-target group and were required to make manual (covert orienting block) or saccadic responses (overt orienting block) to peripheral stimuli occupying one of four peripheral locations. An analysis of target reaction times indicated that while IOR was present under all circumstances, it did not vary as a function of target location. A careful examination of our methods points to the importance of controlling set size (the number of possible target locations) in IOR studies.