Campaign advertising and its effects : the case of Mexico

This dissertation explains how and under what conditions voters are affected by campaign advertising, taking particular account of the conditioning role played by political knowledge and ad tone. It builds on psychological research showing that people make regular mistakes in attribution, evaluation, and decision making; that they tend to give greater weight to negative than to equally credible positive information; that they better match their political choices with their interests and values when they are more politically knowledgeable; and that cognitive shortcuts cannot fully compensate for meager political knowledge. I introduce a psychological theory of how individuals react to campaign advertising in light of: (1) their political knowledge and (2) their natural impulse to give greater weight to negative information (i.e., negativity bias). Using data from an original laboratory experiment conducted in Mexico City in 2012 and from the 2006 Mexico Panel Study, I examine the effect of campaign advertising on the attribution of candidates' character traits, the evaluation of candidates' policy proposals, and vote intentions. I show that campaign advertising's effects on the attribution of candidates' character traits and the evaluation of their policy proposals are conditioned by the voter's degree of political knowledge and the ad's tone (negative or positive). I also show that campaign advertising has a significant, indirect effect on vote intentions through its effect on the attribution of candidates' character traits and the evaluation of their policy proposals. Finally, I explain why negative advertising has systematically bigger effects on voting behavior than equivalent positive advertising. I look at the case of Mexico to shed light on the effects of campaign advertising in developing democracies. Since most academic research has looked at the United States, this thesis intends to deepen our understanding of campaign advertising in comparative perspective, looking at a country where the thinness of party identification, the ambiguity of issue ownership, and the novelty of the party system renders voters more susceptible to information in campaign advertising.