Social control can be done in lots of ways: laws, advertising, culture and peer pressure. Now we can put gaming and mobile phones on the list.

John Rula, a graduate student in engineering at northwestern University, and Fabian Bustamante, associate professor of electrical engineering and computer science, came up with a way to get people to go places they might ordinarily not go. The concept is called "crowd soft control," and combines incentives with mobile applications to nudge people in a certain direction.

PHOTOS: Top 10 Social Networking Sites

The researchers used a game, which involved "zapping" ghosts on a campus. The concept is simple: you get points for zapping a ghost when your phone's camera spots one. The ghosts are displayed first on a map, and then, when the player gets close enough, the augmented reality functions on newer phone models show the ghost on the phone's screen. Each time a ghost appears, the player snaps a picture, and zaps the ghost.

Snapping the photo is fun for the phone owner, but the actual photo itself can be useful for the greater good. For example, a photo can go into a database that would be used to create a map of a campus or a downtown area or to create a 3D view of a building or monument.

DNEWS VIDEO: Science and Technology Help Find True Love

"We have been staring at the basic idea, that of using somebody else's carrot to drive people out of their routine paths, for a few years," Bustamante wrote in an email to Discovery News. "It came, in part, from our interest on the idea of urban sustainability — how to manage the rapid growth of cities and its environmental impact. There is a lot of really cool work on sensing in this space, but much of it relies on the assumption that you are going to get the necessary coverage… and the fact is that, even with the most popular game, that's hard to do."

Bustamante added that he'd read about an augmented reality Pac-Man game a few years ago, and the idea of providing incentives to get the kinds of measurements necessary via a game seemed like a good one.

Applications such as Google's Street View, or 3-D rendering of an area or building, require a lot of photos from many different angles. But not many people take pictures of the back of the Lincoln Memorial or Northwestern's Charles Deering Library. Incentivizing them with a ghost game could get them to do that.

It isn't just good for mapping and making 3-D models, either. The two scientists also experimented with sensing noise around the campus. They requested that volunteers take audio measurements with their phones. Most measurements get taken in high-traffic areas — after all, that's where people tend to go. But using the ghost hunter game in conjunction with the noise measurements gave a much better picture of the situation campus-wide, because players were willing to go out of their way.

BLOG: Providing Climate Data For The Masses

The words "crowd soft control" sound a bit ominous, though it's not a lot different from the kinds of incentives applications such as Foursquare use (going to that favorite coffee shop is incentivized by a point system). There are ethical considerations: Rula and Bustamante say in the paper that any participant has to be told what is happening to the photos they take, for instance.

Then there is the issue of providing incentives to go to places that aren't safe. Bustamante said at a certain point you have to trust a gamer's common sense, and if anyone were to design such a game that there might have to be some curation (like what Apple does with the App Store). That said, this might end up being a better way to crowdsource certain kinds of data, and even make networks more efficient by moving users to areas where the traffic is lighter.

Photo: Red X’s represent the location of Flickr photos near Deering Library; white circles represent photos taken by people playing the ghost hunter game. Credit: John Rula and Fabian E. Bustamante / Northwestern University