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 American Facebook users to make guesses about their personalities and behavior, and even 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 — endorsing everything from pop stars to soda pop. That means an ever-expanding pool of data available to marketers, managers, and just about anyone else interested in users' inner lives, especially those who aren't careful about their privacy settings.
Stillwell and his colleagues scooped up a bucketful of that data in the way that many advertisers do — through apps. Millions of Facebook users have surveyed their own personal traits using applications including a program called myPersonality. Stillwell, as owner of the app, has received revenue from it, but declined to say how much.
The study zeroed in on the 58,466 U.S. test takers who had also volunteered access to their likes.
When researchers crunched the "like" data and compared their results to answers given in the personality test, patterns emerged in nearly every direction. Since the study involved people who volunteered access to their data, it's unclear if the trends would apply to all Facebook users.
The study found that Facebook likes were linked to sexual orientation, gender, age, ethnicity, IQ, religion, politics and cigarette, drug, or alcohol use. The likes also mapped to relationship status, number of Facebook friends, as well as half a dozen different personality traits.
Some likes were more revealing than others. Researchers could guess whether users 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, and to 85 percent when telling Democrats from Republicans. Identifying drug users was far trickier — researchers got that right only 65 percent of the time, a result scientists generally describe as poor. Predicting whether a user was respectively a child of divorce was even dicier. With a 60 percent success rate, researchers were doing just slightly better than random guesses.
The linkages ranged from the self-evident to the surreal.
Men who liked TV song-and-dance sensation "Glee" were more likely to be gay. Men who liked professional wrestling were more likely to be straight. Drinking game aficionados were generally more outgoing than, say, fans of fantasy novelist Terry Pratchett. People who preferred pop diva Jennifer Lopez usually gathered more Facebook friends than those who favored the heavy metal sound of Iron Maiden.
Among the more poignant insights was the apparent preoccupation of children of divorce with relationship issues. For example, those who expressed support for statements such as "Never Apologize For What You Feel It's Like Saying Sorry For Being Real" or "I'm The Type Of Girl Who Can Be So Hurt But Still Look At You & Smile" were slightly more likely to have seen their parents split before their 21st birthday.
Some of the patterns were difficult to understand: The link between curly fries and high IQ scores was particularly baffling.
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.
For the unknown number of users whose preferences are public, Stillwell had this advice: Look before you like.
The like button is "quite a seductive thing," he said. "It's all around the Web, it's all around Facebook. And it's so easy."
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Clickjackers on Facebook entice users to copy and paste text into their browser bar by posting too-good-to-be-true offers and eye-catching headlines. Once the user infects his own computer with the malicious code, the clickjackers can take control of his account, spam his friends and further spread their scam. For example, clickjacking schemes hit Facebook soon after bin Laden's death and spread like wildfire by purporting to offer users a glimpse at <a href="http://www.huffingtonpost.com/2011/05/04/bin-laden-death-video-hoax_n_857730.html" target="_hplink">video or photos of bin Laden's death</a>.
Fake Polls Or Questionnaires
If you click on an ad or a link that takes you to questionnaire on a site outside Facebook, it's best to close the page. When you complete a fake quiz, you help a scammer earn commission. Sometimes the quiz may ask you to enter your mobile number before you can view your results. If the scammers get your number, they could run up charges on your account.
Phishers go after your credentials (username, password and sometimes more), then take over your profile, and may attempt to gain access to your other online accounts. Phishing schemes can be difficult to spot, especially if the scammers have set up a page that resembles Facebook's login portal.
Phony Email Or Message
<a href="http://www.facebook.com/help/?page=1187" target="_hplink">Facebook warns</a> users to be on the lookout for emails or messages from scammers masquerading as "The Facebook Team" or "Facebook." These messages often suggest "urgent action" and may ask the user to update his account. They frequently contain links to malware sites or virus-ridden attachments. They may even ask for your username and password. The best advice Facebook offers is to report the sender and delete the messages without clicking anything.
Money Transfer Scam
If a friend sent you a desperate-sounding Facebook chat message or wall post asking for an emergency money transfer, you'd want to help, right? Naturally. That's what makes this scam so awful. The point is to get you to wire money to scammers via Western Union or another transfer service.
Fake Friend Request
Not all <a href="http://www.huffingtonpost.com/2011/02/10/facebook-friend-request-spam_n_821584.html?page=1" target="_hplink">friend requests</a> come from real people, despite Facebook's safeguards against bots. Some Facebook accounts exist purely to establish broad connections for spamming or extracting personal data from users, so watch out whose friend requests you accept.
Fake Page Spam
Malicious pages, groups or event invitations aim to trick the user into performing actions that Facebook considers "abusive." For instance, a fake invite might offer a prize if you forward it to all your friends or post spammy content on their walls. Sometimes a scammer will set up fake pages as a front for a clickjacking or phishing scheme.
Malicious apps are pretty common on Facebook these days. They can be a cover for phishing, malware, clickjacking or money transfer schemes. Oftentimes, the apps look convincingly real enough for users to click "Allow," as they would do with a normal Facebook app. However, rogue apps use this permission to spread spam through your network of friends. For example, the recent "<a href="http://www.huffingtonpost.com/2011/04/08/facebook-closing-accounts-scam-app_n_846737.html" target="_hplink">Facebook Shutdown</a>" scam spread by claiming that Facebook would delete all inactive accounts except those that confirmed via app installation.
The Koobface Worm
The <a href="http://en.wikipedia.org/wiki/Koobface" target="_hplink">Koobface worm</a> is getting on in years (it first appeared in late 2008) and has been mostly scrubbed from the site, but Facebook still warns users to look out for it. Koobface spreads across social networks like Facebook via posts containing a link that claims to be an Adobe Flash Player update. Really, the link downloads malware that will infect your computer, hijack your Facebook profile and spam all your friends with its malicious download link. This worm affects mostly Windows users.