Choice as a Moderator of Placebo Expectation Effects: Additional Support From Two Experiments

Abstract

Two experiments investigated the hypothesis that treatment choice enhances placebo treatment efficacy. In Experiment 1, prior to a pain task, participants were given either an expectation that two (inert) products could reduce pain or no expectation. In addition, participants either selected between the two products or were assigned a product to use. Participants given both the placebo expectation and treatment choice reported the lowest pain. Experiment 2 conceptually replicated this finding using a placebo paradigm with aversive auditory stimuli. Additional control conditions indicated that a choice availability (rather than choice restriction) explanation best accounted for these results.

Notes

Note. Adjusted means account for pre-manipulation pain ratings.

¹Three participants had missing values for pain ratings from the first trial and thus the degrees of freedom for this analysis are reduced.

Note. Adjusted means account for pre-manipulation discomfort ratings.