Abstract
Object-substitution masking (OSM) occurs when all items in a visual-search display are flashed briefly, with the masking stimulus surrounding the target remaining on view alone. Two experiments investigated how stimulus-salience affects OSM. The salience of target and nontarget items in a search display was manipulated through color. In Experiment 1, on a random one third of the trials the target was uniquely colored, making it highly salient; on one third of trials one nontarget was uniquely colored; on the remaining trials, no items were uniquely colored. We predicted that when the target was salient, target localization and identification would be facilitated, and OSM would be reduced. In contrast, we predicted that when a salient distractor was present target localization and identification would be hampered, and OSM would be exacerbated. This general pattern was observed in Experiment 1. In Experiment 2 we asked whether these salience effects were stimulus-bound or were contingent on top-down strategies. Experiment 2 was identical to Experiment 1, except that only one nontarget was uniquely colored. Color was thus task-irrelevant. Results showed that distractor salience influenced performance only when the mask and target terminated concurrently (i.e., trailing-mask-duration of 0 ms.). Critically, performance was not influenced by salience when a trailing-mask was presented. These results show that stimulus-salience influences OSM only when salience is task relevant. This is consistent with the idea that only task-relevant information contributes to the creation of a perceptual hypothesis.