Learning to Suppress Salient Distractors in the Target Dimension: Region-Based Inhibition Is Persistent and Transfers to Distractors in a Nontarget Dimension

It was shown previously that observers can learn to exploit an uneven spatial distribution of singleton distractors to better shield visual search from distractors in the frequent versus the rare region (i.e., distractor location probability cueing; Sauter. Liesefeld, Zehetleitner, & Muller. 2018). However, with distracters defined in the same dimension as the search target, this comes at the cost of impaired detection of targets in the frequent region. In 3 experiments, the present study investigated the learning and unlearning of distractor location probability cueing and the carry-over of cueing effects from same- to different-dimension distractors. All experiments involved a visual search for an orientation-defined singleton target in the presence of either a more salient color-defined (different-dimension) or orientation-defined (same-dimension) distractor singleton. and all were divided into a learning session and a subsequent test session. The present study showed that with same-dimension (but not with different-dimension) distractors, the acquired cueing effect persists over a 24-h break between the training and test session and takes several hundred trials to be unlearned when the distribution is changed to even (50%/50%) in the test session. Furthermore, the target location effect as well as (somewhat less marked) the cueing effect carries over from learning with same-dimension distractors to test with different-dimension distractors. These carry-over effects are in line with the assumption that the learned distractor suppression effects are implemented at different levels in the hierarchical architecture of search guidance: the saliency map with same-dimension distractors versus a dimension-based level below the saliency map with different-dimension distractors.