Placebo-like analgesia via response imagery

Eur J Pain. 2017 Sep;21(8):1366-1377. doi: 10.1002/ejp.1035. Epub 2017 Apr 19.

Abstract

Background: Placebo effects on pain are reliably observed in the literature. A core mechanism of these effects is response expectancies. Response expectancies can be formed by instructions, prior experiences and observation of others. Whether mental imagery of a response can also induce placebo-like expectancy effects on pain has not yet been studied systematically.

Methods: In Study 1, 80 healthy participants were randomly allocated to (i) response imagery or (ii) control imagery. In Study 2, 135 healthy participants were randomly allocated to (i) response imagery with a verbal suggestion regarding its effectiveness, (ii) response imagery only, or (iii) no intervention. In both studies, expected and experienced pain during cold pressor tests were measured pre- and post-intervention, along with psychological and physiological measures.

Results: Participants rated pain as less intense after response imagery than after control imagery in Study 1 (p = 0.044, ηp2 = 0.054) and as less intense after response imagery (with or without verbal suggestion) than after no imagery in Study 2 (p < 0.001, ηp2 = 0.154). Adding a verbal suggestion did not affect pain (p = 0.068, ηp2 = 0.038). The effects of response imagery on experienced pain were mediated by expected pain.

Conclusions: Thus, in line with research on placebo effects, the current findings indicate that response imagery can induce analgesia, via its effects on response expectancies.

Significance: The reported studies extend research on placebo effects by demonstrating that mental imagery of reduced pain can induce placebo-like expectancy effects on pain.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Analgesia / methods*
  • Cold Temperature
  • Female
  • Humans
  • Imagery, Psychotherapy*
  • Male
  • Pain / etiology
  • Pain / prevention & control*
  • Pain / psychology*
  • Pain Threshold / psychology
  • Placebo Effect*
  • Suggestion
  • Young Adult