Capture by colour: evidence for a domain specific singleton capture

The ability to prioritise certain stimuli above others in a visual scene is a clear benefit when visually searching. The calibration of our attentional system to respond to certain features has been referred to as the adoption of Attentional Control Settings. Despite decades of research, the nature of attentional control settings and the features they can be calibrated to respond to is still unclear. Past research has established that the attentional system can be set to search for particular features (e.g. red), for the odd-one-out in a display (singleton detection mode), or for target-nontarget relations (e.g. redder, larger). Recently, Folk and Anderson (2010) also suggested the existence of a search mode that responds only to singletons in the colour domain. Here we test this claim to determine whether previous evidence for this new search mode can be explained by singleton detection mode (Experiment 1), or a relational set for items of lower luminance (Experiment 2). Participants completed a spatial cueing task, in which they reported the identity of a target whose defining feature varied unpredictably between two possible colours. On each trial participants were presented with one of four cues. In Experiment 1 cues consisted of the two target colours, a target dissimilar colour, and a rotating motion cue. In Experiment 2 cues were the two target colours, a target-dissimilar colour that shared the target-nontarget luminance relation, and a target-dissimilar colour whose luminance relation was opposite to that of the target-nontarget relation. An analysis of participants’ response times indicated that participants may have been using both singleton detection and a set for colour singletons at different times throughout Experiment 1, and ruled out the alternative possibility of a relational set for luminance (Experiment 2). These results suggest it is possible for participants to adopt an attentional set to respond to colour singletons, though this strategy is not used exclusively under the current conditions