Facebook might be inadvertently outing its gay users to advertisers, according to a new study.
Researchers have discovered that different targeted advertising is being sent to users' accounts if they have described themselves as gay or straight.
The discovery could mean that people who wish to keep their sexuality private may be sharing it with advertisers without their knowledge.
A team from Microsoft and Germany's Max Planck Institute created six fake profiles: two straight men, two straight women, a gay man and a lesbian. They wanted to see if Facebook targeted ads based on sexuality, and so the profiles were left
otherwise completely the same.
The team then monitored what ads each virtual user was sent over a period of a week. They found that the ads displayed on the gay man's profile differed substantially from those on the straight one. Many of these adverts were not obviously adverts
for services that only gay men would require, and half of them did not mention the word gay in the text.
The researchers write in the paper: The danger with such ads, unlike the gay bar ad where the target demographic is blatantly obvious, is that the user reading the ad text would have no idea that by clicking it he would reveal to the advertiser
both his sexual-preference and a unique identifier (cookie, IP address, or email address if he signs up on the advertiser's site).
The loophole means that any advertisers who collect data such as Facebook IDs could match a person's sexual preference with their unique ID and their name.
Last week it emerged that vast amounts of data – including the names of individual members and their online friends – were passed to internet advertising firms, with tens of millions of people thought to have been affected. The leaks were
possible even when members had deliberately set their privacy options to the maximum secrecy levels.
Security experts warned that the details could be used – when combined with other publicly available information – to build up a detailed picture of an individual's interests, friendship circle and lifestyle.
Around 25 different advertising and data firms were receiving the information, an investigation by the Wall Street Journal found. It was passed to them by firms whose apps – games and other features – operate on Facebook and not by the
social networking site itself.