Limitations in attending to a feature value for overriding stimulus-driven interference.

Six experiments were conducted to examine the effect of knowledge of a target for overriding stimulus-driven interference in simple search tasks (Experiments 1-3) and compound search tasks (Experiments 4-6). In simple search when the target differed from nontargets in orientation, a singleton distractor that had an orientation equivalent to that of a target interfered with search for the target. When the singleton distractor was less salient than the target with respect to the target-defining feature, it still caused interference. Such within-dimensional, nonsaliency-based interference also occurred in compound search tasks. In contrast, no interference occurred when a singleton distractor was defined in cross-dimension in a simple search task. When a compound search task was used, the salient distractor interfered with the search for a less salient target. These results are discussed in terms of their applicability to existing models and the limitations of top-down penetrability of a feature processing stage.