The impact of task-irrelevant reward on object-based attentional selection in conflict contexts

Previous research has demonstrated the influence of task-irrelevant reward on object-based attention in non-conflict contexts. However, it remains unclear whether object-based attention emerged and how task-irrelevant reward guide object-based attention in conflict contexts. Therefore, the present study adopted a variant of two-rectangle paradigm to investigate the impact of task-irrelevant reward on object-based attention in conflict contexts across three experiments. Experiment 1 observed object-based effects when combing the two-rectangle paradigm with the Stroop task. Experiment 2 used color character as target and found object-based effects in the incongruent-unrewarded condition, not in the incongruent-rewarded condition. The difference can be due to faster response in the incongruent-unrewarded condition for invalid same-object trials. Experiment 3 adopted monetary objects as target and observed reversed object-based effects in the incongruent-high-rewarded condition, not in the incongruent-low-rewarded condition. This was due to faster response in the incongruent-low-rewarded condition than in the incongruent-high-rewarded condition for invalid same-object trials. These findings demonstrated that task-irrelevant reward can affect the object-based attention in conflict contexts, and different types of rewards may share a common mechanism in their impact on object-based attention. Ultimately, this study provided further support for the attentional spreading theory.