Goal Activation, Expectations, and the Placebo Effect.

Abstract

Motivational factors receive little attention in current theories of the placebo effect. Reasons for this position are reviewed, and an argument is made for reconsidering the influence of motivation on the placebo effect. The authors hypothesize that nonconscious goals alter reactions to a placebo expectation. Specifically, the authors predict that the placebo effect is most likely to occur when individuals have a goal that can be fulfilled by confirmation of the placebo expectation. The authors tested this notion in 5 experiments. The results demonstrate the role of motivation in the placebo effect across a variety of symptom domains and via 4 different goal activation techniques. Moreover, this moderating effect occurred for both positive and negative placebo expectations, across different placebo effect measures, and in brief laboratory experiments as well as in lengthier studies. It is argued that theories regarding the placebo effect should incorporate motivational factors. Keywords: expectations, goals, health, placebo effectThe word placebo entered the English language around the 13th century (Shapiro, 1964). The word was translated from Vulgate Latin, meaning to please, to give pleasure, to suit, and to satisfy (Lasagna, 1986;Lewis, 1953;Shapiro & Shapiro, 1997). Early medical definitions include "a medication given to please" (Dorland, 1901) and "medicines prescribed more to please the patient than for its therapeutic effectiveness" (Fox, 1803).These initial conceptualizations of a placebo clearly possess a strong motivational element. That is, a placebo was originally viewed as a medication or treatment that was administered to fulfill a need or desire of the patient. In contrast, most recent reviews and research articles on the placebo effect either ignore or discount the potential impact that motives can have on placebo responding (e.g., Ader, 1997;Amanzio & Benedetti, 1999;Bienenfeld, Frishman, & Glasser, 1996;Kienle & Kiene, 1996;Kirsch, 1997;Montgomery & Kirsch, 1996;Ross & Olson, 1982;Stewart-Williams & Podd, 2004). The aim of this article is to reintroduce motivational features to the theory of the placebo effect. We begin by presenting a brief review of the relevant literature and discussing the dominant theoretical perspectives of the placebo effect. Next, we present a model of placebo responding based on recent goal activation research. We then report five studies conducted to assess this motivationally oriented account. The Placebo EffectWhat is the placebo effect? Although a wide array of definitions currently exist (see

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“…In five studies, participants were divided into two groups [31]. One group was given a cooperative prime, which would therefore enhance the motivation to cooperate.…”

“…The goal activation model [31] of placebo responding is based on the hypothesis that response to expectancy induced placebos is enhanced if that response satisfies other goals. In five studies, participants were divided into two groups [31].…”

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“…Diante disso, o efeito placebo passa a ser impulsionado pela expectativa de que um determinado produto irá desencadear um resultado específico e, sendo assim, a expectativa por uma determinada reação conduz para que a reação seja, de fato, gerada (Geers, Weiland, Kosbab, Landry, & Helfer, 2005).…”