Washington, March 18 (IANS): Researchers can garner vast amounts of information bearing on pollution, epidemics, transportation, from cameras, audio recorders and other applications built into cell phones, cheaply and efficiently.

But how to get mobile users to cooperate? "We can 'soft control' users with gaming or social network incentives to drive them where we want them," said study co-author Fabian Bustamante of Northwestern University.

For example, a game might offer extra points if a player visits a certain location in the real world, or it might send a player to a certain location in a virtual scavenger hunt, according to a Northwestern statement.

To test soft control, researchers created Android games, including one called Ghost Hunter in which a player chases ghosts around his neighbourhood and "zaps" them through an augmented reality display on his phone.

In actuality, the player's zapping motion snaps a photo of the spot where the ghost is supposedly located, said Bustamante, associate professor of electrical engineering and computer science at Northwestern.

In Ghost Hunter, researchers are able to manipulate where the ghosts are placed. Some are placed in frequently travelled areas, others are located in out-of-the-way, rarely photographed locations.

Participants were willing to travel well out of their regular paths to capture the ghosts helping researchers collect photos of Northwestern's Charles Deering Library from numerous angles and directions - a far broader range of data than the random sampling found on Flickr.

"Playing the game seemed to be a good enough vehicle to get people to go to these places," said John P. Rula, McCormick graduate student, who led the study.

If this technology were implemented on a larger scale, users would need to be notified that their data was being collected for research purposes, Bustamante said.

"Obviously users need to know where their data is going," he said, "and we take every measure to protect user privacy."

These findings were presented at the XIIIth Workshop on Mobile Computing Systems and Applications (HotMobile).