Does Utility Bias Mental Simulations of Risky Events?

Does the utility of an outcome influence people’s assessment of risk and uncertainty? Growing evidence suggests that people often rely on mental simulations to evaluate probability and risky events. However, prior experimental findings offer conflicting predictions about how utility biases this mental sampling process. Across four experiments (total N=206, with Experiment 4 pre-registered), we investigated the influence of utility using a random generation paradigm. These responses were then compared to probability judgments and predictions. While we identified individual differences, the majority of participants exhibited neutrality, with no systematic impact of utility on their sampling distributions. Nevertheless, biases emerged under specific conditions, including a preference for smaller or more probable outcomes as the starting point of simulations and optimism in single-response predictions. Additionally, we found evidence suggesting that probability judgments, predictions, and random generation tasks may rely on a shared underlying mental process. Our findings suggest that models of judgment and decision-making should account for individual differences in utility influences, particularly distinguishing between unbiased sampling and optimistic sampling—the selective over-representation of high-utility outcomes.