Inhibition of return and nonspecific preparation: separable inhibitory control mechanisms in space and time.

I examined the relation between two inhibitory processes operating on spatial and temporal representations. In two experiments, participants had to detect a peripheral target that was presented after a variable interval following the onset of an uninformative peripheral cue. For the shortest cue-target interval, target detection was faster at the cued than at the uncued location, but this effect was reversed for the longer cue-target intervals. This finding has been taken to reflect a buildup of space-related inhibition over time, known as inhibition of return. Also, target detection was slower when the cue-target interval of the preceding trial was longer than that of the current trial than when this was not so. This sequential effect has been taken to reflect an intertrial carryover of time-related inhibition. Crucially, the spatial and temporal effects were additive in both experiments, suggesting a modular organization of the underlying inhibitory processes.