プラセボにはおそらく、2つの主要なメカニズム「無意識な条件反射と、意識的な期待」があると考えられている。[Matthias Breidert, Karl Hofbauer:"REVIEW ARTICLE - Placebo: Misunderstandings and Prejudices", Dtsch Arztebl Int 2009; 106(46): 751–5 DOI: 10.3238/arztebl.2009.0751] SUMMARY Background: The role of placebos is often misunderstood, leading both to overvaluation and to inappropriate disdain. The effect of a placebo that contains no pharmacological