Facebook members will find out from 17:00 BST whether they are among the 87 million potential users whose data was shared with Cambridge Analytica.
Every account holder will receive one of two notices informing them whether their data was breached.
The tech giant said people will also be shown what apps they use and what data those apps may have gathered.
Facebook has additionally suspended a data analytics firm called Cubeyou, ahead of an investigation.
The tech giant will look into into whether Cubeyou collected data for academic purposes and then used it commercially, following a partnership with Cambridge University in the UK.
The investigation follows allegations reported by CNBC, regarding a personality quiz called “You Are What You Like”, also known as “Apply Magic Sauce”.
Cubeyou denies the allegations. Both the firm and Cambridge University state that the app made it clear that data was for use in both academic and business purposes.
In an emailed statement received by Bloomberg, Ime Archibong, vice-president of product partnerships, said Cubeyou’s apps would all be banned from the platform if the data firm “refuses or fails” the audit.
Cubeyou said it has always complied with Facebook’s rules.
The news comes as Facebook chief Mark Zuckerberg prepares to give two days of testimony to US Congress in Washington regarding the recent data scandals.
The You Are What You Like website was created by Cubeyou in partnership with Cambridge University’s Psychometric Centre.
The university said that those who took part would have consented to their data being used “for both academic and business purposes” as it was written in the terms and conditions on the site – and added that all data was anonymised.
However, on the current terms and conditions for Apply Magic Sauce, the university states that the site may only be used for “non-profit academic research”.
“Cubeyou merely designed the interface for a website that used our models to give users insight on their data,” the university said.
“We have had no contact with Cubeyou since June 2015.”
The University centre was also implicated in the Cambridge Analytica scandal, as one of its academics developed the quiz which harvested the data that was acquired by Cambridge Analytica’s possession.
Cambridge University denied working with Cambridge Analytica or its parent company SCL and said it had never provided any data, algorithms or expertise.
What is Cubeyou?
It is one of a number of firms set up to help businesses such as publishers and advertisers target their marketing. It is unknown whether it has also helped campaigns spread political messages, as was the case with Cambridge Analytica.
On its website, data firm Cubeyou describes itself has having “all the best consumer data sources in one place”.
“Identify consumers not only by their demographics or consumption habits but by leveraging the whole spectrum of their personalities, interests and passions,” it says.
Other Facebook developments include:
- Apple co-founder Steve Wozniak told USA Today that he was leaving Facebook as he was concerned about the way many tech firms make money from personal data
- Facebook confirmed that it was working on a feature that would enable users to delete messages they had already sent from the inbox of the recipients. However, the firm told The Verge news site that it “may take some time”. It followed news that messages from Mark Zuckerberg had been “unsent” in this way
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