PT - JOURNAL ARTICLE AU - Maël Lebreton AU - Shari Langdon AU - Matthijs J. Slieker AU - Jip S. Nooitgedacht AU - Anna E. Goudriaan AU - Damiaan Denys AU - Judy Luigjes AU - Ruth J. van Holst TI - Two sides of the same coin: monetary incentives concurrently improve and bias confidence judgments AID - 10.1101/099382 DP - 2017 Jan 01 TA - bioRxiv PG - 099382 4099 - http://biorxiv.org/content/early/2017/01/10/099382.short 4100 - http://biorxiv.org/content/early/2017/01/10/099382.full AB - Most decisions are accompanied by a feeling of confidence, i.e., a subjective estimate of the probability of being correct. Although confidence accuracy is critical, notably in high-stakes domains such as medical or financial decision-making, little is known about how incentive motivation influences this metacognitive judgment. In this article, we hypothesized that motivation can, paradoxically, deteriorate confidence accuracy. We designed an original incentive-compatible perceptual task to investigate the effects of monetary incentives on human confidence judgments. In line with classical theories of motivated cognition, our results first reveal that monetary incentives improve some aspects of confidence judgments. However, over three experiments and in line with our hypothesis, but unpredicted by normative or classical motivated cognition theories, we further show that incentives also robustly bias confidence reports: the perspective of potential gains (respectively losses) bias confidence upward (respectively downward), with potential detrimental consequences on confidence accuracy. Connecting our findings with recent models of confidence formation, we demonstrate that these two effects of incentives have dissociable signatures on how confidence builds on decision evidence. Altogether, these findings enrich current cognitive and evolutionary models of confidence, and may provide new hints about its healthy or pathological miscalibration.Significance Statement Most decisions are accompanied by a feeling of confidence, i.e., a subjective estimate of the probability of being correct. Although achieving accurate confidence judgments is theoretically fundamental for individual decision-makers, miscalibrations such as overconfidence appear to be “widespread, stubborn, and costly” (D. Kahneman, in Thinking Fast and Slow. 2011). In this manuscript, we investigated the influence of incentive motivation on confidence accuracy in humans. In a series of behavioral experiments, we found that, although incentives can improve confidence accuracy, they also paradoxically systematically bias confidence judgments, thereby creating detrimental miscalibrations such as overconfidence. These findings have important implications for cognitive and evolutionary models of confidence, and may provide new hints about its healthy or pathological miscalibration.