The invention relates to a computer implemented method of controlling a display on a first computer device connected via a communication network to a plurality of other computer devices, the method comprising: receiving user inputs from the first and other computer devices during interaction with a game rendered on the display of each computer device, the game being played by users of the computer devices over the communication network; storing the user inputs in computer storage and generating user behavior data based on the user inputs; accessing computer storage holding a plurality of contact identifiers of the users and controlling the display of the first computer device to display only a selected set of the stored contact identifiers, wherein the set of contact identifiers is selected to be displayed based on the user behavior data.