A popular subscription service many Iowans use to watch movies and TV shows on-demand or on DVD is collecting a wealth of data about our viewing habits, according to a University of Iowa researcher.

Communication studies professor Tim Havens says he’s been researching Netflix for months and he finds it remarkable how much information the service is amassing. “They do know an awful lot about us,” Havens says. “They know, not just what we watch and how we rate it, but they know when we pause, they know how long we pause, they know when we rewind and watch things over and over and collect all of that data. It’s really important to realize you’re being surveilled while you watch Netflix.”

Unlike the familiar Nielson ratings for broadcast television, Netflix doesn’t make any of its ratings public. Havens says some of that data is being used to make original programming available only to Netflix subscribers, like “House of Cards” or “Orange is the New Black.”

Still, he has concerns about how the numbers are crunched, since they’re kept private. “When they run these algorithms that say ‘House of Cards’ is a good series to put on, who are they actually looking at? I don’t think they’re looking at all of their viewers,” Havens says. “Are they screening out certain viewers who they know, for instance, might be black, and they’re not interested in reaching black viewers so they focus primarily on 18-to-34-yearly men because they know those are the people who spend the most money.”

Havens says the policies of Netflix are troubling as he sees the “potential for a Big Brother scenario” to develop. Still, the way that data is mined and used is considered a benefit to many subscribers, as Netflix can recommend other movies and TV shows you like, based on how you rate what you’ve watched. Havens says those recommendations are proving to be right about 90% of the time.

Havens says, “If we watch a film on Netflix and we rate it in a particular way, that tells them a certain amount about what we think, but if we pause it, if we rewind, if we watch half of it and then stop, that’s really important data for them to have so they can recommend to another person who they think has similar viewing habits whether they may or may not like the film.”

Netflix will sometimes release an entire season of a new program all at once, leading to what some people call “binge-watching,” where they’ll spend a whole weekend doing little else but burning through all of those episodes. Havens says he prefers the term “marathon viewing,” which he says isn’t really a new phenomenon.

“If you think about cable and even in the broadcast era, there have always been these marathons,” Havens says. “So all of these channels have run marathons for years. In a sense, it’s sort of the same idea. The difference is, the audience actually gets to choose when they want to watch all of those episodes.”

Havens, by the way, is not a Netflix subscriber.