Heather L. O'Brien is faculty member at the iSchool, University of British Columbia. Her research expertise lies in the area of user engagement with digital media. Specifically, her work revolves around the nature of user engagement and building theory in this area; measuring user engagement, especially the development of robust self-report measurements; and investigating user engagement in information seeking and retrieval contexts. Paul Cairns is a Reader in the Department of Computer Science at the University of York, UK.His research is in the area of Human-Computer Interaction but he has a particular interest in the experience of playing digital games. He was one of the first researchers to empirically establish what players meant by being immersed in a game and with colleagues developed the Immersive Experience Questionnaire to measure immersion. He has also worked extensively on the notion of social presence in games and applied to understanding training effectiveness in complex simulations.