5Allan, L. G., & Siegel, S. (2002). A signal detection theory analysis of the placebo effect. Evaluation & the Health Professions, 25(4), 410-420.
6Amanzio, M., & Benedetti, F. (1999). Neuropharmacological dissection of placebo analgesia: expectation-activated opioid systems versus conditioning-activated specificsubsystems. The Journal of Neuroscience, 19(1), 484-494.
7Amanzio, M., Polio, A., Maggi, G., & Benedctti, F. (2001). Response variability to analgesics: a role for non-specific activation of endogenous opioids. Pain, 90, 205-215.
8Beecher, H. K. (1955). The powerful placebo. Journal of the American Medical Association, 159(17), 1602-1606.
9Benedetti, F. (1996). The opposite effects of the opiate antagonist naloxone and the cholecystokinin antagonist proglumide on placebo analgesia. Pain, 64(3), 535-543.
10Benedetti, F., Amanzio, M., & Maggi, G. (1995). Potentiation of placebo analgesia by proglumide. The Lancet, 346(8984), 1231.