Choice-induced preference change and the free-choice paradigm: A clarification

Positive spreading of ratings or rankings in the classical free-choice paradigm is commonly taken to indicate choice-induced change in preferences and has motivated influential theories as cognitive dissonance theory and self-perception theory. Chen and Risen (2010) argued by means of a mathematical proof that positive spreading is merely a statistical consequence of a flawed design. However, positive spreading has also been observed in blind choice and other designs where the alleged flaw should be absent. We show that the result in Chen and Risen (2010) is mathematically incorrect, although it can be recovered in a particular case. Specifically, we present a formal model of decision making that satisfies all assumptions in that article but implies that spreading need not be positive in the absence of choice-induced preference change. Hence, although the free-choice paradigm is flawed, the present research shows that reasonable models of human behavior need not predict consistent positive spreading. As a consequence, taken as a whole, previous experimental results remain informative.