Background and aims. The pain experiences can be modulated by information on how other people who underwent the same painful stimulation rated the intensity of pain. This study examined whether 1) information about pain ratings coming from a group of people will be more effective in shaping placebo analgesia than information coming from a single individual, 2) information about pain ratings coming from individuals previously observed in the same experimental situation will produce a stronger placebo effect than information coming from anonymous participants.
Methods. Participants were assigned to one of the four experimental groups or the control group. Participants from the experimental groups received information on how other people rated the intensity of pain stimuli. Their ratings were marked as bars on the VAS. The VASs presenting low pain ratings were displayed after the presentation of a white circle, while the VASs presenting moderate pain ratings were presented on the black background. Participants from the first and third experimental groups were presented with ratings of an individual, while participants from the second and fourth experimental groups were presented with ratings of a group of people. Participants from the third and fourth experimental groups had previously watched a recording showing individuals who provided pain ratings. Then participants rated the intensity of pain stimuli preceded by a white circle and delivered without any visual cues.
Results. The results are presented on the poster.
Conclusions. This study allows learning more about the effect of social information concerning pain on individual pain perception.

THE ROLE OF THE SOURCE OF SOCIAL INFORMATION IN THE FORMATION OF PLACEBO ANALGESIA