They began to search actively for the signal, eventually achieving perfect scores in tracking and identifying the correct location of the invisible light source.

BBC: Lab rats 'acquire sixth sense'

In order to choose a relevant deal for the user at the correct time, location information would need to be collected about the user before noon, even if the Groupon mobile application is not running on the device at that time.

FORBES: Groupon Explains Why It Wants To Constantly Track Customers' Whereabouts