LONDON (AP) — Clicking those friendly blue “like” buttons strewn across the Web may be doing more than marking you as a fan of Coca-Cola or Lady Gaga.
It could out you as gay.
It might reveal how you vote.
It might even suggest that you’re an unmarried introvert with a high IQ and a weakness for nicotine.
That’s the conclusion of a study published Monday in Proceedings of the National Academy of Sciences. Researchers reported analyzing the likes of more than 58,000 Facebook users to make guesses about their personalities and behavior, and whether they drank, smoked or did drugs.
Cambridge University researcher David Stillwell, one of the study’s authors, said the results may come as a surprise.
“Your likes may be saying more about you than you realize,” he said.
Facebook launched its like button in 2009, and the small thumbs-up symbol has since become ubiquitous on the social network and common across the rest of the Web as well. Facebook said last year that roughly 2.7 billion new likes pour out onto the Internet every day. That means an ever-expanding pool of data available to just about anyone else interested in users’ inner lives, especially those who aren’t careful about their privacy settings.
The study found that Facebook likes were linked to sexual orientation, gender, age, ethnicity, IQ, religion, politics and use of substances.
Some likes were more revealing than others. Researchers could correctly distinguish between users who identified themselves as black or white 95 percent of the time. That success rate dropped to a still impressive 88 percent when trying to guess whether a male user was homosexual Identifying drug users was far trickier — researchers got that right only 65 percent of the time, a result scientists generally describe as poor.
Jennifer Golbeck, a University of Maryland computer scientist who wasn’t involved in the study but has done similar work, endorsed its methodology, calling it smart and straightforward and describing its results as “awesome.”
But she warned of what the work showed about privacy on Facebook.
“You may not want people to know your sexual orientation or may not want people to know about your drug use,” she said. “Even if you think you’re keeping your information private, we can learn a lot about you.”
Facebook said the study fell in line with years of research and was not particularly surprising.
“The prediction of personal attributes based on publicly accessible information, such as ZIP codes, choice of profession, or even preferred music, has been explored in the past,” Facebook’s Frederic Wolens said in a written statement.
Wolens said that Facebook users could change the privacy settings on their likes to put them beyond the reach of researchers, advertisers or nearly anyone else. But he declined to say how many users did so.