A newly published research paper suggests that Facebook's ad delivery system discriminates along racial and gender lines, even when advertisers target their content to a wide audience.
Researchers spent $8,500 on ads, and found that housing and job ads were shown to different demographics even though they were set to be targeted at identical audiences.
This comes on the heels of US housing officials' recent charge that Facebook enables housing discrimination.
A new research paper published on Wednesday has revealed that Facebook's ad targeting can discriminate by race and gender, even when advertisers request that their ads are shown to a broad audience.
The paper was put together by six researchers from Boston's Northeastern University, the University of Southern California, and policy group Upturn.
The researchers spent $8,500 running dozens of ads on the platform to determine whether Facebook's ad targeting was skewing certain ads towards or away from certain groups.
In one case, they put together ads for houses up for sale or rent in North Carolina.
They found that ads for houses on sale were delivered to an audience that was 75% white users. Ads for houses for rent were shown to a more mixed demographic.
They also ran identical ads for houses while varying the image: in one case an advert contained a white family, in the other a black family. The ad when run with the white family was served to 85% white users, while the same ad with the black family was served to an audience of 73% white users. This is despite the fact the researchers set the ads to be targeted identically.
The researchers also ran job ads, and found that the kind of job they were advertising affected who was targeted. Ads for jobs in the lumber industry reached users who were 72% white and 90% men. Supermarket cashier jobs were delivered at to an audience of 85% women, while jobs with taxi companies went to a 75% black audience.
The issue at the heart of the findings is not that Facebook is deliberately skewing ad results along racial and gender lines, but rather that its ad-targeting systems could be doing so automatically.
The paper has not yet been peer-reviewed, although The Economist showed it to six experts in the field who said the research appeared solid.
The research comes at an awkward time for Facebook, as the Department of Housing and Urban Development (HUD) last month charged Facebook with "encouraging, enabling, and causing housing discrimination." This came after Facebook announced it was taking steps to prevent housing discrimination on the platform.
"We stand against discrimination in any form. We've announced important changes to our ad targeting tools and know that this is only a first step. We've been looking at our ad delivery system and have engaged industry leaders, academics, and civil rights experts on this very topic — and we're exploring more changes."