Motivational concordance: an important mechanism in self-help therapeutic rituals involving inert (placebo) substances.

We tested the contribution of two mechanisms, response expectancy and motivational concordance, to reported psychological benefit from a popular, biologically inactive, self-help, complementary therapy (a placebo). Flower essences were taken by 251 people for self-selected symptoms and were randomized to receive three different kinds of information. When the flower essence was presented as a spiritual therapy, then baseline spirituality (beta=.35, P=.01) and expectancy (beta=.25, P=.03) independently predicted outcome. When flower essences were presented as an affirmation (i.e., nonspiritual) therapy, then spirituality negatively (beta=-.27, P=.03) and expectancy (beta=.33, P=.01) predicted outcome. For both groups, expectancy predicted outcome after controlling for spirituality and compliance, but did not after controlling for ease of task completion. Expectancy failed to predict outcome in the nonenhanced ritual group. The results suggest that motivational concordance is an important therapeutic mechanism for real-life placebos.