Evidence for the additive effects of dispositional negative mood regulation expectancies and placebo-induced expectancies on mood recovery.

Abstract

Low negative mood regulation expectancies (NMRE) are associated with greater anticipated and experienced negative mood states, as well as with coping strategies that prolong these states. Individuals with low NMRE may be especially responsive to placebos because confidence in an external source of mood improvement can provide the positive mood expectancies and motivation for active coping that they typically lack. This study investigated how NMRE and placebo-induced expectancies contribute to mood recovery. Participants (N=125) completed personality scales, including NMRE, online. During a subsequent in-person session, participants were randomly assigned to one of three conditions: (1) placebo treatment-participants learned of a mood-enhancing treatment and received it; (2) treatment deprivation-participants learned of the same treatment, but did not receive it; (3) control-treatment was never mentioned. Participants also completed measures of mood, active coping, and expectations. NMRE was a stronger predictor of mood recovery than placebo-induced expectancies regardless of group assignment. Additionally, pessimistic expectations arose when participants believed treatment was being deprived, and these participants exhibited the least active coping. Our results confirm the reliability of NMRE in predicting affective outcomes and suggest that personality and placebo-induced expectations have additive effects on mood recovery.