Cognitive load modulates attentional capture by color singletons during effortful visual search

Color singletons that are irrelevant to locating a visual target do not typically capture attention if visual search is effortful. In contrast, when search is efficient color singletons are often found to capture attention. Such distraction by a color singleton can be modulated by single-task vs. dual-task manipulations when visual search is efficient. This is due, presumably, to the increased cognitive load in the dual-task condition, which interferes with top-down attentional control. This study investigated whether capture by a color singleton is also modulated by single-task vs. dual-task manipulations when visual search was effortful. The results of three experiments revealed that attentional capture effects were absent in a single-task condition and were present in a dual-task condition, but only when the identity of the color singleton is not associated with the target response-set. When the identity of the color singleton was relevant to the response-set it captured attention in both the single-task and in dual-task conditions.