New research from the US (appropriately) suggests individual political ads on TV have only a minor impact on determining how a person will vote, regardless of message, context, sender and receiver.
That’s not to say whole campaigns are pointless, the researchers stress, but it does call into question the value of tailoring ads for specific audiences.
“There’s an idea that a really good ad, or one delivered in just the right context to a targeted audience, can influence voters, but we found that political ads have consistently small persuasive effects across a range of characteristics,” says Alexander Coppock from Yale University, lead author of a paper in the journal Science Advances.
“Positive ads work no better than attack ads. Republicans, Democrats and independents respond to ads similarly. Ads aired in battleground states aren’t substantially more effective than those broadcast in non-swing states.”
Social scientists have generally been of the view that persuasive messages tend to result in small effects because persuasion only works well under particular sets of circumstances, Coppock and colleagues say.
However, it has been difficult to synthesise the results of previous experiments into one coherent theory, because different experiments hold variables constant at inconsistent levels, and contain divergent research designs, instruments, and sampling methods.
They conducted their study over 29 weeks during the 2016 US presidential primaries and general election. Participants were divided at random into groups and assigned to watch campaign advertisements or a placebo – a car-insurance commercial – before answering a short survey.
The researchers selected ads using real-time, ad-buy data and news coverage of each week’s most important ads. They tested ads attacking or promoting Republican candidate Donald Trump and Democratic candidate Hillary Clinton as well as commercials concerning primary candidates, such as Republican Ted Cruz and Democrat Bernie Sanders.
They analysed the ads’ effects on survey respondents across several variables, including the candidate, party or political action committee that sponsored them; whether they were positive or negative in tone; the partisanship of those viewing the ads; the time to election day when they aired; whether they were viewed in a battleground state or not; and whether they aired during the primary or general election.
They found that, on average and across all variables, the ads moved a candidate’s favourability rating respondents only .05 of a point on the survey’s five-point scale, which is small but, they note, statistically significant given the study’s large size.
The effect on determining for whom individuals intended to vote was a statistically insignificant 0.007 of a percentage point.