Instrumental Control Enhances Placebo Analgesia

Abstract

Placebo analgesia is a robust phenomenon readily observed in both experimental and clinical settings. While researchers have begun to unpack its psychobiological mechanisms, important questions remain regarding how we can capitalize on the placebo effect to improve clinical pain outcomes. The current study tested whether providing individuals with instrumental control-that is, control over if and when they administer a treatment-is capable of enhancing placebo analgesia. Using an established electrocutaneous pain design, 87 healthy volunteers either received placebo conditioning with instrumental control over treatment administration, standard passive placebo conditioning without any control over treatment administration, or were allocated to natural history control group with no conditioning and were later tested at equivalent shock intensity with and without placebo applied. Both placebo groups demonstrated initial placebo analgesia. Importantly, however, those provided with instrumental control demonstrated significantly larger and longer lasting placebo analgesia as well as reduced anticipatory autonomic arousal than those receiving standard passive placebo conditioning. This suggests that providing instrumental control over treatment administration can facilitate placebo analgesia by enhancing its magnitude and durability. As such, providing instrumental control over treatment administration may be a cheap and ethical method of using the placebo effect to improve clinical pain outcomes. PERSPECTIVE: Placebo research typically involves passive designs where individuals have no control over treatment administration. We present novel data demonstrating that providing control over treatment administration substantially enhances both the magnitude and duration of placebo analgesia. As such, where possible, providing control may improve clinical pain outcomes via the placebo effect.

Keywords: Placebo; choice; expectancy; instrumental control; pain.