Facebook's job advert targeting algorithm appears to discriminate on gender and age, a nonprofit campaign group has said.

• Global Witness said it investigated Facebook's job ad targeting system for potential bias.
• The nonprofit campaign group said the system "appears to operate in a discriminatory manner."
• Facebook said it was "reviewing the findings" of the investigation.

Facebook's job advert targeting system appears to discriminate based on gender and age, a non-profit campaign group has said.

Global Witness said it investigated the system with unpublished and published posts, and concluded that it appeared to show signs of bias.

In a report shared with Insider, Global Witness said it placed two job ads with Facebook "with the intention of using different forms of discriminatory targeting: one ad was targeted to exclude women, the other to exclude people over the age of 55." Facebook accepted both ads for publication, seemingly in violation of its own non-discrimination policy, Global Witness said.

Global Witness said it agreed to abide by the non-discrimination policy when placing the ads. It said it pulled the ads before they were published.

Global Witness said it also ran a separate test to see whether Facebook's algorithms showed signs of automated bias. The group said it placed four ads for real job openings, for mechanics, preschool nurses, pilots, and psychologists. Global Witness said it ticked a box saying it wanted Facebook to show the ads to the people most likely to click on them.

The group said that after the ads were published, it found that 96% of users shown the ad for mechanic jobs were men, and 95% of users shown the ad for preschool nurse jobs were women. Global Witness said that 75% of users shown the ad for pilot jobs were men, and 77% who were shown the ad for psychologist jobs were women.

Naomi Hirst, head of Global Witness' Digital Threats campaign, said: "It's really shocking that Facebook's own algorithm appears to target job ads in such a discriminatory way. Targeting adverts for nursery workers at women and mechanic jobs at men - what century does Facebook think we're living in?"

A Facebook spokesperson said: "Our system takes into account different kinds of information to try and serve people ads they will be most interested in, and we are reviewing the findings within this report.

"We've been exploring expanding limitations on targeting options for job, housing and credit ads to other regions beyond the US and Canada, and plan to have an update in the coming weeks."

Global Witness said it had asked the UK Equality and Human Rights Commission (EHRC) to investigate whether Facebook's practices break the equality laws. It said it had also asked the UK data watchdog, the Information Commissioner, to investigate whether Facebook may have broken Europe's stringent data protection laws.

Concerns have been raised previously about apparent discrimination within Facebook's ad targeting system.

The US Department of Housing and Urban Development (HUD) filed charges against Facebook in March 2019, alleging that its ad targeting system enabled housing discrimination. A month later, a research paper suggested that ads for housing and jobs were discriminating against users on the basis of ethnicity and gender.