Inhibition of return and the attentional set for integrating versus differentiating information.

Cuing a location with an uninformative cue leads to a facilitatory effect at that location shortly afterward and later (about 300 ms) to a negative effect called inhibition of return (IOR). Until recently, it was argued that IOR occurs in detection and localization tasks, but not in discrimination tasks. However, the authors of several recent studies have demonstrated IOR effects in discrimination tasks, although at a later cue-to-target stimulus onset asynchrony (SOA). In this study, the authors examined why IOR occurs at a later SOA in discrimination tasks. In Experiments 1 and 2, different time courses of exogenous cuing effects in detection and discrimination tasks were established. In Experiment 3, the authors examined the role of an attentional set on the time course of exogenous cuing effects by manipulating the proportion of trials in which a distractor is presented in the location opposite the target. A new framework for understanding exogenous cuing effects and their dependence on endogenous attention is proposed.