Does Outcome Utility Bias the Mental Simulations of Risky Events?

Does the utility of an outcome influence people's assessment of risk and uncertainty? Prominent theories propose that people rely on mental simulation to evaluate probabilities and risky events, yet prior empirical findings is mixed as to whether and how utility biases this process. Across four experiments (total N=206, with Experiment 4 pre-registered), we tested this question using a random generation paradigm, in which participants mentally simulated gamble outcomes and said them out loud. Then we compared these responses with 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, an optimism subgroup emerged, with a larger proportion of optimistic participants when the monetary context was more salient. Additionally, outcome utilities have similar effects on probability judgments, predictions, and random generation tasks, consistent with the proposal that these tasks are related to each other and may all rely on mental simulation. These findings indicate that utility does not uniformly distort mental simulation, but can do so for a stable subgroup under particular motivational contexts, and they motivate cognitive models that capture both unbiased and optimistic forms of mental sampling.