This weekend I saw a man diligently snapping photos of hidden security cameras, tucked high above the entrance to a Manhattan building. I never would have noticed the cameras had it not been for the man and his oversized camera, but there they were, watching me as I passed by. Maybe he was a member of the New York Civil Liberties Union's ongoing Surveillance Camera Project, or maybe someone from the NYPD's Lower Manhattan Security Initiative. I don't know what he was doing, but it was a clear reminder that (at least in big cities) there's always a good chance I'm being watched.

Surveillance can stir up feelings of intrusion or deception; in other contexts, safety and security. On social networks, however — Facebook in particular — we get to be both the watcher and the watched, changing the type of Big Brother relationship typically associated with such activities. Researchers have coined this "social surveillance," in which we simultaneously stalk and let stalk. It's changing the power dynamics and hierarchy of conventional surveillance, and introducing an element of reciprocity. Social surveillance is normalizing what was once considered creepy.

"I found that there was always a sort of mixed approach to social surveillance, compounded by the fact that when people talk about creeping or stalking, they identify with both roles," said researcher Daniel Trottier, whose upcoming paper analyzes this dynamic on Facebook.

We know we're being watched — but instead of making us more averse to sites like Facebook, social surveillance has made us feel okay with creeping too. As Microsoft researcher Alice Marwick wrote in a new paper, "[P]ractices framed variously as stalking, watching, creeping, gazing or looking are characteristic of social media use, but this social surveillance creates panoptic-type effects."

In a pantopticon prison scenario, the guards can view prisoners at all times, but the prisoners don't know when they're being watched. In turn, the prisoners internalize the very idea of being watched. The same is true on Facebook, says Trottier, except that the relationship becomes even more complicated as users try to internalize the idea of being watched by friends, parents, employers and exes all at the same time. This causes us to make very calculated, tailored acts of self-presentation on Facebook, the result of a high awareness of being watched. Although no true panopticon prison exists, Facebook might be the closest thing we have (okay, you're not imprisoned, but they do make it pretty hard to leave.)

Social surveillance also does a good job of masking conventional surveillance, and people often forget that their friends aren't the only ones watching. Trottier's research found that people are more aware of how an ex is watching them, and to a lesser extent a potential employer, but when it comes to things like advertising agencies or law enforcement they either don’t know or don’t care.

"People don’t always think about it in terms of surveillance, but if you take a textbook definition of surveillance it describes about 85 percent of what people do on Facebook," he said.

Like the man taking pictures of the security cameras, these researchers are trying to understand when we're okay with creeping. Surveillance, when it's social, somehow makes it less invasive — even though our social networks probably gather far more private information than most traditional surveillance methods ever could.