A survey experiment was run by staging a fictitious election for mayor in the (fictitious) city of Castegufo. Voters in this election were the respondents of an online survey, in which they were told to consider that they just moved to a town with an upcoming mayoral election. The survey experiment was run with two or three candidates to mayor. The candidates were designed to have similar individual characteristics and no ideological differences. Participants to this survey experiment were shown a video ad from each of the candidates, performed by a professional actor.
In the experiment with three candidates, the video of the incumbent and of one of the opponents contained a positive message, whereas the campaign of the other opponent was randomized. The treatment group was shown a video with a negative message against the incumbent, while the control group watched a video with a positive message.
In the experiment with two candidates, the video of the incumbent had a positive message, whereas the video of the opponent was randomized: the treatment group was shown the video with a negative message against the incumbent, the control the one with a positive message.
In both experiments (with two or three candidates), respondents were asked to indicate whom they would vote for.
Positive Spillovers from Negative Campaigning, with Tommaso Nannicini and Salvatori Nunnari, American Journal of Political Science, 2021. Online Appendix, Replication Data.
Negative advertising is frequent in electoral campaigns, despite its ambiguous effectiveness: Negativity may reduce voters’ evaluation of the targeted politician but may have a backlash effect for the attacker. We study the effect of negative advertising in electoral races with more than two candidates with a large-scale field experiment during an electoral campaign for mayor in Italy and a survey experiment in a fictitious mayoral campaign. In our field experiment, we find a strong, positive spillover effect on the third main candidate (neither the target nor the attacker). This effect is confirmed in our survey experiment, which creates a controlled environment with no ideological components or strategic voting. The negative ad has no impact on the targeted incumbent, has a sizable backlash effect on the attacker, and largely benefits the idle candidate. The attacker is perceived as less cooperative, less likely to lead a successful government, and more ideologically extreme.
Meet the Candidates
The (other) Challanger
Treatments: Positive, Negative & Aggressive Video Ads by an Opponent
Positive video ad
Negative video ad
Aggressive video ad
Video ad by the incumbent mayor, Baldi.
Video ad by the (untreated) opponent, Vanni.