Expectations and Placebo Response: A Laboratory Investigation into the Role of Somatic Focus
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- Geers, A.L., Helfer, S.G., Weiland, P.E. et al. J Behav Med (2006) 29: 171. doi:10.1007/s10865-005-9040-5
It has been theorized that expectations are an important causal determinant of the placebo effect. Placebo expectations, however, do not always yield placebo effects. In a laboratory study, we tested the hypothesis that one's level of somatic focus moderates the effect of placebo expectations on placebo responding. We also varied whether participants were told the placebo was a drug, could either be a drug or placebo, or was a placebo. The results revealed that individuals who thought they were taking a drug (i.e., unconditional expectations) reported more placebo symptoms when they closely focused on their symptoms. Individuals told they may or may not be receiving a drug (i.e., conditional expectations) did not differ from control participants regardless of how closely they attended to their symptoms. The findings have theoretical implications for expectancy models of the placebo effect as well as for practical research comparing the type of expectations held by individuals in clinical trials and clinical practice.