Biasing predictive processing of interoceptive information affects implicit spirituality but not religiosity

In a predictive processing framework, religiosity and spirituality (R&S) have been linked to increased reliance on prior beliefs and decreased prediction error monitoring. In addition, R&S might be differentially related to processing exteroceptive and interoceptive information. The present study aimed at manipulating different components of the predictive processing model (prior beliefs and prediction error monitoring) in interoception, and evaluating the resulting changes in the implicit R&S. In a variant of the heartbeat discrimination task (HDT), we used a sham transcranial magnetic stimulation protocol to induce prior beliefs about a decrease or increase of the heartbeat frequency (Experiment 1). Prediction error monitoring was modulated by manipulating error feedback reliability in the same HDT (Experiment 2). Results showed that the point of subjective equality and the decision criterion shifted towards the direction of the induced prior compared to the baseline condition only in the direction of the decreased heartbeat frequency (Experiment 1), while the sensitivity decreased with unreliable error feedback compared to reliable one (Experiment 2). Crucially, implicit S, but not R, that were measured after the HDT increased following the prior beliefs induction; no significant change was observed after the unreliable error feedback. The effects in Experiment 1 were modulated by the prevalence of autistic personality traits. Together, the results support the predictive coding account of R&S where increased reliance on prior beliefs, but not on prediction error monitoring, has a crucial role in the R&S experiences, and demonstrate the differential input of interoceptive signals in the R&S.