Abstract
Detecting flashes of light is faster when two light stimuli appear, one in each visual fields, than when just one stimulus appears in a visual field. This ‘redundancy gain’ phenomenon shows the cooperation of redundant signals for common task goal. Then, what if they are in the context of competition? Two perceptually identical objects might compete with each other as much as two different objects of a category. Alternatively, they might cooperate to form a stable, veridical representation. These conflicting possibilities were tested with three behavioral experiments. Experiment 1 and 2 used a name-picture Stroop task. In each trial, participants categorized a famous target name into that of an actor or a sports player while ignoring a flanking famous face distractor, which could be either congruent (e.g., an actor's name and face) or incongruent (e.g., an actor's name and a player's face). In redundancy condition, the same face was added in the opposite side of the face distractor. As results, relative to a single distractor, Stroop interference was enhanced by two perceptually identical distractors. Importantly, this redundancy effect disappeared when two faces were the same at the response level, but different at the perceptual level. This effect was replicated with nonface objects in Experiment 3, which further showed that redundancy effect was not affected by time differential display of identical distractors. Overall, current study found a phenomenon of ‘redundancy loss’ and suggests that redundant presentation of a stimulus overcome attentional constraints by facilitating perceptual processing.