It is often assumed that attentional capture by salient visual events is triggered in a bottom-up fashion irrespective of currently active task sets. For example, reaction times (RTs) during visual search for shape singletons (e.g., unique diamond targets presented among distractor circles) are delayed by the presence of salient but task-irrelevant color singletons (e.g., Theeuwes,
1991), suggesting that such color singletons are able to attract attention even when they are irrelevant for current selection goals (see also Ester & Awh,
2008; Nordfang, Dyrholm, & Bundesen,
2012, for similar observations). However, the ability of salient visual objects to capture attention is often contingent on whether they match target-defining attributes. This task-set dependent nature of attentional capture was demonstrated in a series of experiments by Folk and colleagues (Folk & Remington,
1998; Folk, Remington, & Johnston,
1992; Folk, Remington, & Wright,
1994) where spatially nonpredictive feature singleton cues preceded visual search arrays. Attentional capture by these cues was assessed by comparing RTs to visual search targets that were presented at cued versus uncued locations. The critical finding was that spatial cueing effects (i.e., faster RTs to targets at cued locations) were only triggered by cues with features that matched a currently active task set, but not by nonmatching cues, indicating that only the former captured attention. For example, color singleton cues produced spatial cueing effects when participants searched for color-defined targets, but not in a task where targets were abrupt onset items. According to the contingent involuntary orienting hypothesis (Folk et al.,
1992), salient visual objects such as feature singletons will capture attention only if they possess attributes that match current task goals, but not when their visual attributes are task-irrelevant.