Repeated Messaging Increases the Durability of Political Persuasion, But Only In the Short Term

What affects the durability of political persuasion? This study evaluates the influence of two factors—the number of times an individual is treated, and the time between treatments—on persuasion around climate change. We conducted a five-wave panel study (N = 2,588), varying exposure to the number of persuasive messages (one versus three messages) and the length of interval between messages (two days or one week). We measure effect durability up to ten weeks after initial exposure. Repeated exposure to persuasive messages more than doubles their durability one week after treatment (from 32% to 83%), however, multiple treatments do not increase absolute persuasion compared to a single treatment. This difference in durability between one and three treatments closes after eight weeks, with 6%-8% of individuals remaining persuaded, with no evidence of backlash or partisan heterogeneity in effects. These findings help explain the role of repetition in the durability of political persuasion messages.