How Large and Long-lasting Are the Persuasive Effects of Televised Campaign Ads? Results from a Randomized Field Experiment

Abstract

W e report the results of the first large-scale experiment involving paid political advertising. During the opening months of a 2006 gubernatorial campaign, approximately $2 million of television and radio advertising on behalf of the incumbent candidate was deployed experimentally. In each experimental media market, the launch date and volume of television advertising were randomly assigned. In order to gauge movement in public opinion, a tracking poll conducted brief telephone interviews with approximately 1,000 registered voters each day and a brief follow-up one month after the conclusion of the television campaign. Results indicate that televised ads have strong but short-lived effects on voting preferences. The ephemeral nature of these effects is more consistent with psychological models of priming than with models of on-line processing. P aid television advertising commands the largest portion of the communications budget in campaigns for the most important elective offices and represents an important source of voter information about candidates. Despite increased use of Internet communications and renewed attention to voter mobilization fieldwork, big campaigns are still essentially paid media battles that aim to persuade voters. Our study addresses two unresolved questions regarding the persuasive influence of mass media campaigns: What is the effect of television and radio campaign advertising on voter preferences? How long do the effects last? After addressing these issues we use our empirical results to consider an important further question: What do our results suggest about how voters process political information?We analyze the findings of a randomized field experiment measuring the size and duration of campaign effects caused by a $2 million television and radio buy. There are two main results. First, across a range of model specifications, television campaign advertisements have a large and statistically significant effect on voter preferences. Second, and perhaps most surpris-Alan S. Gerber is Professor, ).The authors are grateful to David Carney and the Texans for Rick Perry Campaign for their willingness to conduct a randomized evaluation and to share their data with us. Special thanks go to Peter Aronow, who assisted with data analysis and manuscript preparation. The authors bear sole responsibility for any errors.ing, the effects of the advertisements dissipate rapidly. Nearly all previous research on advertising effects has ignored the issue of decay and implicitly assumes that decay, if it occurs, takes place over weeks or months. We find that just a week or two later, the advertisement's effects have all but disappeared.The arresting finding of sizable effects and rapid decay has important implications for our understanding of campaign strategy and the effect of campaign spending on election outcomes. The results also have implications for alternative models of voter learning. As we explain at greater length in the discussion section of our paper, a large initial response followed by a q...

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“…54 Although high volume TV ads ($3 million per week) can exert a strong effect on voter preferences, shifting the target candidate's standing by six percentage points, these effects are smaller and statistically equivocal effects one week later, and vanquished thereafter. 54 Decay was apparent among RISE participants, as indicated by recall of ad content. One year out, participants recognized ads that they had seen, but were not necessarily able to recall the exact messages each displayed.…”