In Virtual Reality one of the key concepts is Presence. Much theoretical research has been done around the immersion that the virtual environments can produce, and usually focus the attention in perceptual issues. But different approaches are emerging in the last months. For instance, Dustin Chertoff has published a new, more holistic theory about presence that analyses cognition and emotion too.
In these post of RoadtoVR you can find an interview with him and references to other theories about presence from Mel Slater or Jessica Brilhart.