The placebo concept

Throughout the medical, psychological, and psychiatric literature, the terminology used to characterize placebos is misleading, imprecise, and conducive to conceptual confusion in research on their effects. To remedy this situation, the present paper does the following: (1) It fills the conceptual lacunae left by the defective traditional locutions; (2) It proposes a lucid and precise new vocabulary to supplant the traditional obscure language in which the results of placebo research are couched; and (3) It illustrates the important conceptual refinement accruing from using the new expressions by thoroughly recasting A.K. Shapiro's influential definition of ‘placebo.’