Online Political Information: Facebook Ads. Electorate Saturation, and Electoral Accountability in Mexico

Horacio Larreguy (Institute for Advanced Study in Toulouse)

October 1, 2020, 11:00–12:30

Room Auditorium 3

Behavior, Institutions, and Development seminar


While inexpensive digital technologies like Facebook can spread misinformation, they could also enhance electoral accountability. We study electoral responses to incumbent performance information disseminated through social media and how these responses vary with information campaign saturation—the share of an electorate directly targeted with information. We evaluate a non-partisan NGO’s campaign that used Facebook ads to inform Mexican citizens about the extent of irregularities in audited government expenditures in their municipality prior to the 2018 general elections. The information campaign was randomized to target 0%, 20%, or 80% of a municipality’s electorate. Around 15% of targeted citizens watched at least part of the Facebook video ad. We find that incumbent parties which engaged in negligible irregularities received around 5 percentage points more votes among citizens living in areas directly targeted by the ads. This effect in treated areas was twice as large under 80% as 20% municipal saturation, while the higher saturation municipalities also generated comparable spillovers among non-targeted citizens within the same municipality. Social interactions between citizens, rather than responses by politicians or media outlets, appear to drive both the direct and spillover effects. Information campaign saturation may then help explain the particularly large impacts of information on voting behavior and electoral accountability when it is disseminated by broadcast and digital mass media.