Trait anxiety is associated with idiosyncratic neural event boundaries during naturalistic movie-watching

Anxiety is associated with altered patterns of attention to images and objects, but how it influences the perception of continuous experiences remains underexplored. Here, we examined how anxiety influences the segmentation of continuous experience into discrete events. Using a large-scale open-access dataset and data-driven methods to detect neural event boundaries, we compared neural event segmentation between healthy adults with high (N=60) and low trait-level anxiety (N=60) as they viewed a short suspenseful film. While the overall temporal event segmentation hierarchy was preserved across groups, higher-anxiety individuals had more idiosyncratic boundaries, exhibiting reduced alignment to both low-anxiety individuals and one another. This divergence was the most pronounced in the dorsal attention and frontoparietal control networks, suggesting that anxiety-related disruptions in top-down attentional control may contribute to less consistent segmentation. Furthermore, boundary variability in anxious participants was higher during moments rated as more anxiety-provoking by a large language model, controlling for arousal, valence, and low-level visual features. Together, these findings suggest that idiosyncratic event models in anxious individuals result in non-normative organization of continuous experience, leading to more individualized and inconsistent event boundaries. Such variability in segmentation may have downstream consequences for prediction, memory, and social cognition, offering a potential neural mechanism by which anxiety influences the interpretation and recall of everyday experiences. Our findings highlight trait-level variability as a lens through which the brain parses information and offers a neurocomputational framework for investigating individual differences in naturalistic event cognition.