Competition with outcome feedback manipulation
We used a between-participants design to manipulate outcome feedback. Participants were randomly assigned to receive one of four types of outcome feedback (victory vs. defeat vs. uncertain competitive outcome vs. no competition (control)). We used a standard version of the Deese–Roediger–McDermott (DRM) paradigmTo stimulate competition, participants were playing against an opponent on the DRM paradigm via two connected computers. To intensify their sense of competition, we also informed them that if they outperformed their opponent, they would get a bonus payment of ￥10. Otherwise, they would only obtain the standard payment for their participation in the study (￥10). At the end of the competition, participants were immediately given information about their performance. Specifically, they received one of three types of outcome feedback (victory vs. defeat vs. uncertain competitive outcome). Regarding the uncertain competitive outcome, participants were informed of their own task performance but had no information about the performance of their opponents. In this way, participants had no way to directly evaluate their performance relative to their opponents. For the other two outcome feedbacks, participants received them at the end of the competition that was appropriate to their group, i.e., that they had won (“you win”) or lost (“you lose”) against their opponents. Due to technical challenges, the outcome feedback that participants received was not based on comparing participants’ performance with their opponents’ performance but pre-determined. Such outcome feedback manipulation inevitably raises a concern with respect to deception of participantsIn the control “no competition” condition, participants were told that they and another person would perform the DRM paradigm independently. As such, no competition occurred between them and they were asked to perform the task as well as possible. Once participants had completed the task, they were given feedback about their own task performance. They were informed that, if their performance level ranked above a predetermined criterion, then they would receive a bonus payment of ￥10. Otherwise, they would only get the standard payment for participating in the experiment. However, like the three competition conditions, immediately after performance feedback, participants rated on a 9-point scale the extent to which they perceived competition, self-confidence, their closeness to the other individuals as well as the level of trust they felt toward them.