In a Scientific American article, titled “The Internet Knows You Better Than Your Spouse Does,” author Frank Luerweg revealed that an online test, which tracks users’ digital footprints to provide a detailed personality analysis, knew many of those tested better than their spouses.

Apply Magic Sauce allows users to connect their Facebook and Twitter accounts so that the algorithm can provide a detailed personality analysis — predicting how competitive, stressed, impulsive, and conservative or liberal the person is.

As reported by Luerweg in his article for Scientific American, “the algorithm’s ability to draw inferences about us illustrates how easy it is for anyone who tracks our digital activities to gain insight into our personalities—and potentially invade our privacy. What is more, psychological inferences about us might be exploited to manipulate, say, what we buy or how we vote.”

Three researchers, Luerweg continued, from the University of Cambridge and Stanford University “trained their algorithm using data from more than 70,000 Facebook users.”

“All the participants had earlier filled out a personality questionnaire, and so their Big Five profile was known. The computer then went through the Facebook accounts of these test subjects looking for likes that are often associated with certain personality characteristics,” Luerweg explained. “For example, extroverted users often give a thumbs-up to activities such as ‘partying’ or ‘dancing.’ Users who are especially open may like Spanish painter Salvador Dalí.”

“Then the investigators had the program examine the likes of other Facebook users. If the software had as few as 10 for analysis, it was able to evaluate that person about as well as a co-worker did. Given 70 likes, the algorithm was about as accurate as a friend,” he reported. “With 300, it was more successful than the person’s spouse. Even more astonishing to the researchers, feeding likes into their program enabled them to predict whether someone suffered from depression or took drugs and even to infer what the individual studied in school.”

You can read the full article at Scientific American.