A review of the literature on the two main models of the placebo effect: expectancy theory and classical conditioning.

Interestingly, the reviewed literature suggests that classical conditioning procedures are one shaping factor but that verbal information can also shape placebo effects. The literature also suggests that conditioning procedures and other sources of information sometimes shape conscious expectancies and that these expectancies mediate some placebo effects; however, in other cases conditioning procedures appear to shape placebo effects that are not mediated by conscious cognition

Link to research: ThePlaceboEffect