Influence of Social Observational Learning on Pain Perception

Abstract

Background: Placebo hypoalgesia is the reduction of pain purely by treatment context. Humans are social beings and learn about their environment by observing others. Research shows observational learning induces placebo hypoalgesia, but its neural underpinnings are not explored. Methods: During EEG acquisitions, twenty-six healthy participants observed a demonstrator experiencing pain on two inert creams on the forearm. He showed painful and neutral expression for each. They then received same creams and recorded their pain ratings. Results: We got 11 responders reporting lower pain (Placebo x = 12.8 ± 3.7, (F (1, 10) = 11.812, p = 0.006)) and 10 non-responders who showed opposite trend (Placebo x = -6.9±3.5, (F (1, 9) = 3.85, p = 0.081)). The peak alpha frequencies during eyes closed resting state did not correlate with placebo response. Conclusion: Social learning does induce placebo in certain people, and further EEG task analysis can help generate an electrophysiological marker for placebo.