Do Expectations Shape Interoceptive Perceptions Across Body Domains? A Sham EMF Study to Test the Predictive Processing Theory.

Objective:According to the principles of predictive processing theory, persistent symptom perception is largely determined by central nervous predictions on somatosensory input. Here, we examine how threat-related expectations shape predictions and interoceptive perceptions across body domains using sham EMF (electromagnetic field) exposure. Methods:Participants (n = 113) were recruited via announcements at the university. Most participants were female (76.1 %) with a mean age of 25.12 years. Participants were divided into two groups (sham EMF on/off). Both groups completed a somatic and a cardiovascular signal detection task (SSDT, cvSDT) in pseudo-randomized order. Sensitivities and response biases were calculated. Self-reports (symptom distress, anxiety) were completed. Group effects were analysed with (M)AN(C)OVAs. In four exploratory regression models response bias and anxiety (state/trait) served as predictors for somatic symptom distress. Results:Participants in the sham EMF group reported significantly higher levels of state anxiety (p = .021, d = 0.44) and, trend-wise, more symptoms during the experiment (p = .065, d = 0.35). Response biases did not differ significantly between the groups (SSDT: p = .782; cvSDT: p = .743). However, higher somatic symptom distress was significantly associated with a more liberal interoceptive response tendency in both tasks in the sham EMF group (two significant models, one trend: (-0.209 ≤ βs ≤ -0.325, adjusted 0.232 ≤ R² ≤ 0.330). Conclusions:A liberal approach was associated with elevated symptom experience across bodily domains and might be considered a transdiagnostic psychopathological risk factor. As research is still scarce, replication studies with valid context manipulations are essential.