Beyond Single-Shot Designs: Repeated Treatments, Affective Polarization, and Democratic Norms

Abstract Although theory and observational work suggest that affective polarization should shape citizens’ support for democratic norms, experimental tests of this causal claim largely find null effects. Most studies assume any impact would be immediate and rely on one-shot manipulations. Yet democratic norms are sticky; brief shifts in partisan feelings may be too weak or fleeting to move them. I therefore test whether repeated treatments over several waves of a survey shift affective polarization and, in turn, support for democratic norms. I find no significant first-stage effects: the treatments do not change respondents’ affective polarization, so repeated exposures do not cumulatively move it and downstream effects on norms cannot be identified. I conclude by considering why my findings differ from studies that report significant effects for similar treatments. Many experiments measure affective polarization as hostility toward the outparty, whereas this study and observational work conceptualize it as the gap between inparty and outparty evaluations.