On the mathematics of the free-choice paradigm

Chen and Risen pointed out a logical flaw affecting the conclusions of a number of past experiments that used the free-choice paradigm to measure choice-induced attitude change. They went on to design and implement a free-choice experiment that used a novel type of control group in order to avoid this logical pitfall. In this paper, we describe a method by which a free-choice experiment can be correctly conducted even without a control group.