31 July 2026Nudges are widely used in public policy and experimental economics, yet many fail to achieve their intended effects. Beyond design considerations, recent studies point to heterogeneity in individuals’ responsiveness to nudges. We argue that this heterogeneity gives nudges a behavioral incidence: just as economists have long studied how the costs of taxes and regulations fall unevenly across individuals, the effects of behavioral interventions may be concentrated among specific segments of the population rather than spread evenly across it. Yet little is known about who these individuals are and why. In this paper, we study one candidate determinant of this heterogeneity: a psychological trait known as locus of control (LOC). LOC refers to the extent to which individuals believe that life outcomes are determined by their own actions (internal locus) rather than by external forces such as luck or situational factors (externa