A collinear distractor impairs local element search regardless of its probability occurrence

Abstract

Salient distractors draw our attention spontaneously even when they do not facilitate our target search. When that occurs, targets close to or overlapping with them are detected and discriminated faster. However, an opposite impairment effect is observed when the salient distractor is a column of continuous linear bars (Jingling and Tseng, 2012). One possible explanation is that observers optimize their search strategy by directing their attention away from collinear distractors but toward the area where targets are six times more likely to appear. We tested this hypothesis by arranging targets to overlap with collinear distractor columns for 60% of the trials. The same search impairment on targets overlapping with or near the collinear distractor persists, which is against the probability hypothesis. Our result suggests that the origin of this effect is at a sensory processing stage not dependent upon information to its probability occurrence.