Anxiety is associated with the persistence of conditioned somatic sensations over time

<p>Somatic symptoms are among the most common and debilitating features of anxiety, yet the mechanisms by which they arise remain poorly understood. We developed a new somatosensory paradigm (adapted from work on auditory hallucinations by Powers et al., 2017), which uses Pavlovian conditioning to induce phantom percepts – where participants report a sensation in the absence of the stimulus. We found that participants in a high-anxiety group (BAI ≥ 16) were more likely to report phantom percepts than low-anxiety controls, and had higher detection rates overall. These differences were not present from the start, but emerged over the course of the task. Computational modelling using a Hierarchical Gaussian Filter showed that this was not because anxious participants weighed prior expectations more heavily against sensory evidence, but because their uncertainty estimates were more stable, and therefore their prior beliefs updated more slowly over time. This result is consistent with evidence that anxiety is associated with difficulties in updating beliefs under changing conditions (Browning et al., 2015; Gagne et al., 2020). Overall, our results refine existing predictive processing accounts of somatic symptoms, pointing to slower accumulation of uncertainty in anxiety as a possible driver of phantom somatic sensations.</p>