Probability cueing of singleton distractor locations in visual search: priority map or dimension based inhibition?
Observers can learn the likely locations of salient distractors in visual search, reducing their potential to capture attention (Ferrante et al. 2018; Sauter et al. 2018a; Wang Theeuwes, 2018a) While there is agreement that this involves positional suppression of the likely distractor location(s) it is contentious at which stage of search guidance the suppression operates: the supra dimensional priority map or feature contrast signals within the distractor dimension. On the latter account, advocated by Sauter et al. target processing should be unaffected by distractor suppression when the target is defined in a different (non suppressed) dimension to the target. At odds with this, Wang and Theeuwes found strong suppression not only of the (color) distractor, but also of the (shape) target when it appeared at the likely distractor location. Adopting their paradigm, the present study ruled out that increased cross trial inhibition of the single frequent (frequently inhibited) as compared to any of the rare (rarely inhibited) distractor locations is responsible for this target location effect. However, a reduced likelihood of the target appearing at the frequent vs. a rare distractor location contributes to this effect: removing this negative bias abolished the cost to target processing with increasing practice, indicative of a transition from priority map to dimension based and thus a flexible locus of distractor suppression. Public Significance Statement Distraction by a salient visual stimulus outside the 'focus' of the task at hand occurs frequently. The present study examined whether and how 'knowledge' of the likely location(s) where the distractors occur helps the observer to mitigate distraction. The results confirmed that observers can learn to suppress distracting stimuli at likely locations. Further, they showed that, the suppression may occur at different levels in the hierarchically organized visual system where the priorities of which objects to be attended in the environment are determined.