Facebook charges more for left-wing political campaigns to advertise to people with right-wing views, and vice versa, which may be exacerbating political polarisation.
UK political parties have spent hundreds of thousands of pounds in the run-up to the general election tomorrow, and one in five dollars that went on political adverts in the US in 2018 was spent online. But new research shows that political advertisers in the US have to pay more to reach beyond their core voting base.
The researchers spent more than $13,000 to promote various adverts using Facebook’s built-in marketing tools to thousands of voters living in North Carolina in July and August. The biggest campaign the team produced targeted 50,000 voters, says Piotr Sapiezynski at Northeastern University in Boston, Massachusetts, one of the paper’s authors.
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The researchers divided Facebook users by their political viewpoint, based on voter registration records and Facebook’s own assessments of the users’ political leanings. They paid to show people adverts taken from pre-existing ad campaigns run by Democratic presidential candidate Bernie Sanders, and the current Republican president, Donald Trump.
Showing a Sanders advert to Republican-leaning voters cost on average three times as much as promoting it to Democrats – and vice versa for Trump ads. “This is a huge financial penalty for trying to show people content they might not agree with,” says Sapiezynski.
Even if a political campaign wants to target all voters equally, Facebook automatically serves up its advert to people more inclined to support the point of view of the politician being promoted, the team found.
“Political campaigns may think if they’re targeting a geographical region, they will reach an audience representative of that region,” says Sapiezynski’s colleague, Aleksandra Korolova at the University of Southern California. “Unbeknownst to that campaign, Facebook delivers ads to the people who are most aligned to it.”
Facebook was not able to provide 91av with a comment before publication. A Facebook spokesperson, commenting on the research, that it served adverts to people that were relevant for them. The spokesperson added that campaigns can reach whoever they want with the right targeting and spending.
“Advertising a mattress or toothbrush is very different to the functioning of democracy,” says Aaron Rieke at Upturn, a research and advocacy group focused on advertising equity, and one of the paper’s co-authors. “Political speech shouldn’t be shunted into little filter bubbles with the same commercial calculus that drives consumer goods.”
Tristan Hotham at the University of Bath, UK, who also works for Who Targets Me, a campaign group promoting transparency in political advertising, says that although the researchers studied US advertising, a similar situation is likely to occur in the UK political advertising space – something Korolova agrees with. “It’s the same algorithm and optimisation logic being used throughout,” she says.
But Hotham says it isn’t clear what effect this is having on democracy. “Asserting for certain that the algorithms are separating us politically from this study is a step too far given when the study was undertaken and who was included,” he says.
Promoting adverts for such diametrically opposed politicians as Trump and Sanders means the experiment may have resulted in extreme findings – the results for more centrist candidates may be more muted, says Hotham.
However, the paper raises important questions about Facebook advertising, says Hotham. Partisan content appeals most to partisans, and Facebook’s advertising ecosystem is based around engagement. “There are systemic problems with Facebook’s ad system, and targeting should either be made very transparent or restricted much further,” says Hotham.
A spokesperson for the UK Electoral Commission declined to comment on the paper’s findings, saying it only regulates political finance.
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