Are They Real? Examining the Regulatory Effects of Non-Deceptive Placebos on Emotional Distress

Abstract

Placebos offer an effective way to manage a host of clinical disorders and nonclinical conditions. However, the commonly held belief that people need to be deceived in order for placebos to work prevents their widespread use. Research on placebos administered without deception (non-deceptive placebos) has challenged this assumption and opens the possibility of harnessing the beneficial effects of placebos. However, as this research accumulates, old placebo issues proliferate, such as controversy about whether the beneficial effects from non-deceptive placebos reflect true effects or are the byproduct of response bias. In four studies, I attempted to address some of these new issues and advance the basic understanding of non-deceptive placebo effects. Chapter I provides an overview of placebos, placebo effects, and non-deceptive placebos. Chapter II tests a novel non-deceptive placebo manipulation and finds beneficial effects on self-reported emotional distress; however, it was not effective for skin conductance response or an implicit cognitive-based measure of emotional reactivity. Chapter II also shows that the non-deceptive placebo manipulation may work for female participants but not male participants, dictating the methodology of subsequent studies. Chapter III replicates this finding with an all-female sample and finds a similar pattern of modulation for self-reported emotional distress but none for skin conductance response. Chapter IV uses a different objective measure but finds null effects on pain tolerance duration. Chapter V uses an objective neural measure and finds that non-deceptive placebos reduced neural measures of emotional reactivity, suggesting that effects are more than response bias and are true psychobiological effects. Chapter V provides important insights into the neural mechanisms and time course of the non-deceptive placebo effect. Non-deceptive placebos appear to increase attentional allocation to emotional stimuli before exerting their regulatory effect at a later time. Taken together, this work presents a nuanced understanding of non-deceptive placebo effects, suggesting that they are indeed true psychobiological effects in specific circumstances: the objective measure must be carefully selected, with the type of manipulation and the time course of beneficial effects in mind. This delayed regulatory finding provides an important insight regarding the beneficial effects of non-deceptive placebos and when these effects should be assessed. Moreover, this work has important translational implications for medical practice, psychopathology, and emotion regulation in daily life.