The relation between motivational concordance and response expectancy

Abstract

Response expectancy is a well-established theoretical mechanism by which placebo effects are thought to be generated [1–3]. The theory posits that the key factor involved in the placebo effect is the response expected by the patient as a result of treatment. Response expectancy is thus principally a cognitive theory—what matters most is what a person thinks, not what he or she does. Recently, a competing theory was developed by Hyland et al. [4] called “motivational concordance.” Motivational concordance differs from response expectancy in that it claims that expectancies do not have a direct influence on the placebo effect. Instead, it posits that it is behavior rather than cognition that is most important in driving placebo responses. In addition, motivational concordance theory holds that, if a particular treatment regimen is in accord with the patient's own preferences and motivations, then the patient will be more likely to engage in that treatment, and it is the behavior itself (i.e., the degree of engagement in treatment) that leads to symptom reduction. In the present issue of this journal, Hyland andWhalley [5] present empirical data in support of motivational concordance as an alternative to response expectancy theory. However, instead of pitting the two against one other, it seems to me that the theories should be integrated. According to Hyland and Whalley, the major divergence between the theories is the centrality of behavior in motivational concordance theory and