Placebo Response Correlates With Hypnotic Suggestibility

Placebo response shares phenomenology and likely overlaps with substrates of cognition and personality. However, inconsistent findings abound regarding the potential link between suggestibility and responding to placebos. Here we directly probe whether suggestibility of the hypnotic type influences placebo response. Fifty healthy undergraduates underwent a standard measure of hypnotic suggestibility— the Harvard Group Scale of Hypnotic Susceptibility. These participants later ingested a placebo capsule in one of two similar conditions: (a) relaxation, wherein we identified the capsule as a strong dose of an herbal sedative, or (b) control, wherein we identified the capsule as inert. We indexed placebo response via changes in heart rate, blood pressure, and self-report measures of relaxation and drowsiness. We hypothesized that placebo response and hypnotic suggestibility would correlate positively in the relaxation condition. Hypnotic suggestibility correlated with subjective but not physiological response to ingesting the placebo sedative capsule. Here we report preliminary findings demonstrating a correlation between hypnotic suggestibility and subjective placebo response.