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

Cuing a location with an uninformative cue leads to a facilitatory effect a t that location shortly afterward and later (about 300 ms) to a negative ef fect called inhibition of return (IOR). Until recently, it was argued that IOR occurs in detection and localization tasks, but not in discrimination t asks. 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 tas ks were established. In Experiment 3, the authors examined the role of an a ttentional set on the time course of exogenous cuing effects by manipulatin g the proportion of trials in which a distracter is presented in the locati on opposite the target. A new framework for understanding exogenous cuing e ffects and their dependence an endogenous attention is proposed.