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Researchers from Northeastern Unviersity, the University of Southern Carolina, and tech accountability non-profit Upturn have released a paper that says Facebook’s ad delivery system itself can steer ads intended to be inclusive toward discrimination without explicit intent. “In a paper titled, ‘Discrimination through optimization: How Facebook’s ad delivery can lead to skewed outcomes,’ co-authors Muhammad Ali, Piotr Sapiezynski, Miranda Bogen, Aleksandra Korolova, Alan Mislove, and Aaron Rieke find that advertiser budgets and ad content affect ad delivery, skewing it along gender and racial lines even when neutral ad targeting settings are used,” reports The Register. From the report:
The researchers found that Facebook ads tend to be shown to men because women tend to click on ads more often, making them more expensive to reach through Facebook’s system. That divide becomes apparent when ad budgets are compared, because the ad budget affects ad distribution. As the paper explains, “the higher the daily budget, the smaller the fraction of men in the audience.” Such segregation may be appropriate and desirable for certain types of marketing pitches, but when applied to credit, employment and housing ads, the consequences can be problematic.

Ad content — text and images — also has a strong effect on whether ads get shown to men or women, even when the bidding strategy is the same and gender-agnostic targeting is used. In particular, the researchers found images had a surprisingly large effect on ad delivery. Ad URL destination has some effect — an ad pointing to a bodybuilding site and an ad pointing to a cosmetics site had a baseline delivery distribution of 48 percent men and 40 percent men respectively. The addition of a title and headline doesn’t change that much. But once the researchers added an image to the ad, the distribution pattern changed, with the bodybuilding site ad reaching an audience that was 75 percent male and the cosmetics ad reaching an audience that was 90 percent female. According to the researchers, their tests suggest, “Facebook has an automated image classification mechanism in place that is used to steer different ads towards different subsets of the user population.”

“In terms of credit, employment and housing ads, the problem with this system is that it discriminates where it shouldn’t: Five ads for lumber industry jobs were delivered to an audience that was more than 90 percent men and more than 70 percent white; five ads for janitorial work were delivered to an audience that was more than 65 percent women and 75 percent black,” the report adds. “Housing ads also showed a racial skew.”

The latest findings come after years of criticism of Facebook’s ad system. Last month, Facebook announced changes to the platform intended to prevent advertisers from deploying unfair credit, employment and housing ads. One week later, the U.S. Department of Housing and Urban Development sued Facebook for violating the Fair Housing Act.