Templates for rejection can specify semantic properties of nontargets in natural scenes

In contrast to standard search templates that specify a target object's expected features, templates for rejection (TFR) may specify features of nontargets, biasing attention away from irrelevant objects. Little is known about TFR, and virtually nothing is known about their role in guiding search across natural scenes. In such scenes, targets and nontargets may not be easily distinguished on the basis of their visual features; it has been claimed that standard search templates may therefore specify target objects' semantic features to guide attention. Here, we ask whether TFR can do so. Noting a limitation of previous procedures used to study standard search templates, we trialed an alternative method to examine semantic templates for nontarget exclusion in natural scene search. We found that when nontargets belonged unpredictably to either of two physically distinct categories, search was less efficient than when targets belonged to one known category. This two-category cost, attributed to inefficient application of search templates, was absent for two physically dissimilar but semantically related categories. Adding a training phase to highlight semantic distinctiveness of two object categories reinstated the two-category cost, precluding stimulus-based accounts of the effect. These patterns were not observed for one-image displays or when observers searched for object categories rather than ignoring them, demonstrating their specificity to TFR, the inadequacy of search-and-destroy models to account for them, and likely basis in attentional guidance. TFR can specify semantic information to guide attention away from nontargets.