We present the first field experiment on how organized interest groups’ television ads affect issue opinions.
We randomized 31,404 voters to 3 weeks of interest group ads about either immigration or transgender non-discrimination. We then randomly assigned voters to receive ostensibly unrelated surveys either while the ads aired, one day after they stopped, or 3 days afterwards.
Voters recalled the ads, but 3 ads had minimal impacts on public opinion, while a 4th’s impacts decayed within one day. However, voters remembered a fact from one ad. Our results suggest issue ads can effect public opinion, but that not every ad persuades and that persuasive effects decay.
Despite the vast sums spent on television ads, our results are the first field experiment on their persuasive power on issues, shedding light on the mechanisms underpinning—and limits on—both televised persuasion and interest group influence.
…We examine the effects of 4 television advertisements on voters’ issue attitudes, issue knowledge, and intent to engage in political activism. The advertisements cover immigration and LGBTQ non-discrimination, 2 salient topics subject to considerable “outside lobbying” over the last decade.
We find that television ads can have effects on public opinion while the ads are airing and that the ads can teach voters facts they remember, contrasting with prior findings on candidate campaign ads (2007, 2018). However, we find that not all ads persuade, and that the ads that do persuade have effects that fade rapidly, consistent with findings from candidate campaigns ( et al 2011; et al 2013; 2018). In short, we find that television advertising can allow groups to temporarily change public sentiment and to inform the public, but that not every ad is effective and that persuasive effects may be short-lived.
…Treatment Implementation and Outcome Measurement: The advertisements aired for 3 weeks, a length of time the partner organizations thought would be sufficient to test the ads’ persuasive power. The advertising firm did not stipulate particular networks or hours for the ads to run. Instead, they could run whenever the television was turned on. Across all voters, the average household was exposed to the ads 19.7×. Put in terms of Gross Rating Points (GRPs), which are defined as 100× the expected number of times an individual in the target audience viewed the ad, the intervention was therefore equivalent to ~1,970 GRPs over the course of 3 weeks—a large volume. (By contrast, et al 2011 randomized media markets to receive up to only 1,000 GRPs per week.) The firm was also able to collect data on how often each household was exposed to an advertisement for a non-random 51% of voters who have newer television technologies, allowing us to estimate treatment-on-treated (TOT) effects among this subgroup.
…We first find large effects on recall of seeing an ad about LGBTQ people. This confirms that the ads were delivered to the treatment group and demonstrates that the ads were memorable. In particular, among all post-treatment survey respondents (regardless of when they were surveyed), we estimate a statistically-significant 5.9 percentage point ITT effect on recall (SE = 0.4, p < 0.001). This effect does not appear to decay; 3 days after the advertisement stopped airing, we still find a 6.0 percentage point increase in recall (ITT, SE = 0.7, p < 0.001). Figure 2 shows that both the ITT and TOT effects are meaningfully sized when expressed in terms of standard deviations.
We also find that the advertisements decrease prejudice against LGBTQ people and increase support for LGBTQ-inclusive policies while the advertisement is airing. However, these effects appear to rapidly decay once the advertisement stopped and are primarily driven by Democratic respondents (Table OA38).
…If an organized group seeks to durably change attitudes, television advertising may not produce effects as large or durable; however, given the low per-person cost of TV ads, our confidence intervals are too wide to form confident conclusions about the relative cost-effectiveness of TV advertising and personal contact.