Repetitive negative thinking is associated with conflict-related neural activity that modulates evidence accumulation.

Repetitive negative thinking (RNT), including worry and rumination, is a transdiagnostic feature of anxiety and depressive disorders and is linked to altered cognitive control. However, the decision-level mechanisms underlying these alterations are not well understood. Here, we examined whether individual variation in RNT is associated with neural and computational markers of conflict processing. Thirty-seven participants completed a flanker task while undergoing electroencephalography, and inhibitory control dynamics were quantified using hierarchical drift diffusion modeling. Behaviorally, RNT was not associated with traditional behavioral markers of conflict processing. At the neural level, higher RNT was associated with a more negative midfrontal conflict N2. Computationally, higher RNT was associated with larger congruent-incongruent differences in drift rate. Similarly, more negative midfrontal N2 activity was associated with greater modulation of drift rate congruency effects. An exploratory mediation analysis indicated that the midfrontal conflict N2 significantly mediated the effect of RNT on drift rate differences between congruent and incongruent trials. These findings indicate that elevated RNT is associated with heightened conflict-related neural activity that increases the degree to which evidence accumulation is modulated by conflict, suggesting a more reactive and context-sensitive engagement of cognitive control.