Effect propensity

In a choice between two options, decision makers can often be roughly divided into three groups: those who strongly prefer the first option, those who strongly prefer the second option, and those whose choices are most sensitive to the specific conditions (Switchers). In any reference state, such as the experimental control, Switchers’ choices are unlikely to be exactly equally divided between the options, which potentially creates a ceiling effect among those most susceptible to influence by the particular conditions or experimental manipulations. The limited growth potential of the option favored by Switchers in the reference state can produce “effect propensity,” whereby any condition or manipulation applied to the reference state is more likely to increase the share of the other option. We test this proposition in a series of studies in the context of choices between safe and risky options and between lower-price/quality and higher-price/quality options. The results indicate that a large majority of conceptually unrelated manipulations tend to increase the choice share of risky and higher-price/quality options. This effect propensity can be reversed when the risky and higher-price/quality options are the status quo alternatives or asymmetrically dominating in the reference state. Alternative explanations for effect propensity are examined. We discuss the implications of effect propensity for the interpretation of research findings, the selection of controls, and theory tests.