Altered neural profile of reward evaluation under risk and ambiguity in intolerance of uncertainty

Intolerance of uncertainty (IU) refers to a tendency to perceive the unknown as threatening and aversive. It is recognized as a trans-situational and transdiagnostic factor that contributes to the development and maintenance of various psychopathologies. While prior research has primarily focused on IU's role in uncertain threat processing, its influence on uncertain reward processing remains poorly understood. This study investigated how IU modulates neural dynamics of reward evaluation under conditions of risk (known probabilities) and ambiguity (unknown probabilities). Electroencephalography was recorded from 38 individuals high in IU and 38 individuals low in IU while they performed a wheel-of-fortune task in which monetary rewards were delivered with either known or unknown outcome probabilities. Results revealed that high-IU individuals exhibited an altered neural profile of uncertain reward evaluation, characterized by reduced differentiation between risk and ambiguity in the reward positivity and enhanced theta valence differentiation under ambiguity relative to risk. By delineating the distinct effects of IU on reward-related neural activity, these findings provide insight into how IU shapes reward processing under different forms of uncertainty and may help inform interventions for psychiatric conditions in which IU plays a central role.