Your pain increases my pain: Exploring the effect of interpersonal synchrony on the transmission of nocebo hyperalgesia

Abstract

Witnessing another's pain can heighten pain in the observer. However, research has focused on the observer’s intrapersonal experience. Here, a social transmission-chain (N=101) explored the spread of socially-acquired nocebo hyperalgesia. Dyads of genuine participants were randomised to ‘Generations’ (G1-G3). G1-Demonstrators, observed by G2-Observers, experienced high/low thermal pain contingent on supposed activity/inactivity of a sham-treatment. G2 became Demonstrators, witnessed by G3-Observers. They experienced fixed low-temperature stimuli irrespective of sham-treatment ‘activity’. G3 then Demonstrated for G4-Observers (a confederate), also experiencing low-temperature stimuli only. Pain ratings, electrodermal activity, and facial action units were measured. G1's treatment-related pain propagated throughout the chain. G2 and G3 participants showed heightened subjective and physiological response to sham-treatment, despite equivalence in stimulus temperature, and G3 never witnessing the initial pain-event. Dyadic interpersonal physiological synchrony (concurrence in electrodermal activity) and psychological synchrony (the Observer’s ability to predict the Demonstrator’s pain), predicted subsequent socially-acquired pain. Implications relate to the interpersonal spread of maladaptive pain experiences.