Effects of relevant and irrelevant color singletons on inhibition of return and attentional capture.

We tested whether color singletons lead to saccadic and manual inhibition of return (IOR; i.e., slower responses at cued locations) and whether IOR depended on the relevance of the color singletons. The target display was preceded by a nonpredictive cue display. In three experiments, half of the cues were response-relevant, because participants had to perform a discrimination task at the cued location. With the exception of Experiment 2, none of the cue colors matched the target color. We observed saccadic IOR after color singletons, which was greater for slow than for fast responses. Furthermore, when the relevant cue color matched the target color, we observed attentional capture (i.e., faster responses at cued locations) with rapid responses, but IOR with slower responses, which provides evidence for attentional deallocation. When the cue display was completely response-irrelevant in two additional experiments, we did not find evidence for IOR. Instead, we found attentional capture when the cue color matched the target color. Also, attentional capture was greater for rapid responses and with short cue-target intervals. Thus, IOR emerges when cues are relevant and do not match the target color, whereas attentional capture emerges with relevant and irrelevant cues that match the target color.