Arrivals of crises often trigger public appeals from policy leaders, attempting to encourage crisis-mitigating behaviors. We ask whether the tone of an appeal changes its effectiveness, and to what extent policymakers know what tone to use. Using a controlled experiment in a large, general-population sample, we first study the impact of appeals and of their emotional tone on contributions to a well-defined crisis mitigation effort. Two equivalent appeals have either positive-tone or negative-tone wordings, and both increase contributions by about 20% compared to no appeal. Next, a sample of policymakers (N=88) is presented with our design and asked to predict the outcome. Although they correctly predict the impact of the positive appeal, they substantially underestimate the effectiveness of the negative one.
