Socially transmitted placebo effects

Medical treatments typically occur in the context of a social interaction between healthcare providers and patients. Although, decades of research have demonstrated that patients’ expectations can dramatically impact treatment outcomes, less is known about the influence of providers’ expectations. Here, we systematically manipulated providers’ expectations in a simulated clinical interaction involving administration of thermal pain and found that patients’ subjective experiences of pain were directly modulated by providers’ expectations of treatment success reflected in the patients’ subjective ratings, skin conductance responses, and facial expression behaviors. The belief manipulation also impacted patients’ perceptions of providers’ empathy during the pain procedure and manifested as subtle changes in providers’ face expression behaviors during the clinical interaction. Importantly, these findings replicated in two additional independent samples. Together, our results provide evidence of a socially transmitted placebo effect, highlighting the importance of how healthcare providers’ behavior and cognitive mindsets can impact clinical interactions.