Surprising Sounds Influence Risky Decision Making

Adaptive behavior requires appropriate responses to environmental uncertainty. Across seven human experiments (total n = 1600), we tested whether task-irrelevant sensory prediction errors (auditory surprises) influence risky decision making. Rare auditory sequences preceding options systematically increased risk taking and decreased choice perseveration (tendency to repeat the previous choice). Manipulating auditory statistics dissociated these effects: when rare sequences consisted only of standard tones, participants were less likely to persevere after rare sequences but did not take more risks. Computational modeling showed these effects were not explained by increased decision noise; instead, value-independent risky bias and perseveration parameters captured behavior. Control experiments eliminated effects when tone sequences were balanced or fully predictable, and surprise effects could be explained by erroneous beliefs. Incidental sounds may influence many everyday decisions.