Effects of volunteering and responsibility on the perceived value and effectiveness of a clinical treatment.

Abstract

Both volunteer and nonvolunteer subjects were randomly assigned to one of two conditions.In the choice condition, subjects were led to believe that they had a choice between two hypothetical relaxation treatments that both they and another subject would receive.Subjects in the second condition were denied the choice of treatment, receiving the treatment chosen by another subject.All subjects, regardless of choice, actually received the same taped relaxation treatment.As predicted, volunteer subjects who were given a choice between treatments significantly valued the treatment more and reported the treatment to be significantly more effective than volunteer subjects who had no choice in the matter.Nonvolunteer subjects, viewing choice as less important than volunteer subjects, were not significantly affected by the subsequent responsibility manipulation, whereas volunteering may be a reliable source of bias, the degree to which the volunteer feels responsible for the success of the outcome appears to predict the direction of the bias.These findings are relevant to both the clinician and to clinical outcome research.