Evaluation for the design of experience in virtual environments: Modeling breakdown of interaction and illusion

New and emerging media technologies have the potential to induce a variety of experiences in users. In this paper, it is argued that the inducement of experience presupposes that users are absorbed in the illusion created by these media. Looking to another successful visual medium, film, this paper borrows from the techniques used in "shaping experience" to hold spectators ' attention in the illusion of film, and identifies what breaks the illusio n/experience for spectators. This paper focuses on one medium, virtual real ity (VR), and advocates a transparent or "invisible style" of interaction. We argue that transparency keeps users in the "flow" of their activities an d consequently enhances experience in users. Breakdown in activities breaks the experience and subsequently provides opportunities to identify and ana lyze potential causes of usability problems. Adopting activity theory, we d evise a model of interaction with VR-through consciousness and activity-and introduce the concept of breakdown in illusion. From this, a model of effe ctive interaction with VR is devised and the occurrence of breakdown in int eraction and illusion is identified along a continuum of engagement. Evalua tion guidelines for the design of experience are proposed and applied to us ability problems detected in an empirical study of a head-mounted display ( HMD) VR system. This study shows that the guidelines are effective in the e valuation of VR. Finally, we look at the potential experiences that may be induced in users and propose a way to evaluate user experience in virtual e nvironments (VEs) and other new and emerging media.