Explicit feedback on target rewards modulates attentional bias in redundant-target detection

Attentional deployment can be shaped by both target location probability and reward value. Yet it remains unclear whether these factors are combined to influence attention allocation or whether attention is preferentially biased toward one dimension. To address this question, we employed a redundant-target detection task combined with Systems Factorial Technology. Targets appeared at the top and/or bottom of the display, with both locations matched in expected value but differing in reward magnitude and target location probability. Participants reported target presence under conditions with and without performance feedback. Our results showed that in the absence of feedback, attention was allocated in parallel across locations, indicating that neither reward nor probability exerted a bias. By contrast, when feedback was introduced, participants shifted toward a sequential allocation strategy. These findings highlight the contextual dependence of attentional strategies and shed light the role of explicit feedback and uncertainty in shaping visual attention and perceptual decision-making.