Title: Fighting Populism on Its Own Turf: Experimental Evidence
Abstract: We evaluate how traditional parties may respond to populist parties on issues that are particularly fitting for populist messages. The testing ground is the 2020 Italian referendum on the reduction of members of Parliament proposed by populist parties. We implement both a large-scale field experiment, with almost one million impressions of programmatic advertising, and a survey experiment. In both settings, the treatments are two video ads: a video providing information on the likely costs of cutting MPs aimed at deconstructing the populist narrative and a video attacking the credibility of the populist politicians, who promoted the reduction of MPS, aimed at reducing trust in them. Our field experiment shows that the latter video is more effective at capturing the viewers’ attention. Moreover, it decreases the turnout rate and, to a lesser extent, the “Yes” votes (in favor of reducing the MPs). We present a theoretical framework based two ingredients – trust in traditional parties and information acquisition – to account for these findings and to provide additional predictions. In the survey experiment, both (unskippable) videos reduce the “Yes” vote and increase the share of undecided. For voter of traditional parties, the effects are concentrated among people with low previous political information. For voters of populist parties, previous political information plays no role.