Deciding for others alters metacognition leading to responsibility aversion.

People are often faced with choices whose outcomes will affect other individuals in addition to themselves. Being responsible for deciding on behalf of others alters choice behavior and increases delegation rates in decisions involving risk and ambiguity. However, it is unknown whether the influence of social responsibility on decision-making acts primarily or directly on risk, loss, and ambiguity attitudes versus more general aspects of cognition. We report a series of experiments on objective magnitude judgments that demonstrate that the influences of responsibility on cognition and behavior extend beyond risk or ambiguity and act at the metacognitive level. Specifically, responsibility for others changes metacognitive biases, leading to a decrease in decision confidence without affecting choice accuracy. Last, we propose and empirically test a normative computational framework based on decision confidence that can explain decisions to assume or delegate responsibility for others without needing to assume changes in risk preferences.