Are pills enough? The influence of information on open-label placebo effects in healthy volunteers

Open-label placebo administration (1 placebo pill per day, with either standard RCT placebo information versus enhanced open-label placebo information) for 5 days compared to a no treatment control condition. Adherence will be assessed via self-report at follow-up after completion of the course of placebo pills (day 6). Enhanced information will follow the talking points outlined by Kaptchuk and colleagues (2010) - namely that placebos are powerful, can produce an automatic healing response, that positive expectations are not necessary but keeping an open mind is important, and that taking pills faithfully (i.e. adherence) is critical. Standard RCT information is similar to that typically provided in RCT studies involving a placebo control condition. Namely, placebos will be described as typically being used as a control treatment, with the capsules containing inert ingredients that have no active physiological effect. Information will be provided verbally to both groups during an initial half hour face-to-face research session. Information provision will take 5 to 10 minutes. At the end of this session, participants will be given lactose-filled vegetarian gelatin placebo capsules to take for the next 5 days.