Immersive virtual reality (immersive VR) is the presentation of an artificial environment that replaces users' real-world surroundings convincingly enough that they are able to suspend disbelief and fully engage with the created environment. Immersiveness is an important element of virtual reality applications, such as VR gaming and VR therapy.
Immersiveness is usually considered on a scale or along a continuum, from least immersive to fully immersive. Typically, user engagement will vary accordingly, although to some extent dependent on individual differences. An inadequately immersive environment will not engage the user, while one that completely replicated the real world could have unpredictable psychological effects. To date, the latter scenario is not an issue because that level of immersiveness has not been achieved.
Elements of virtual environments that increase the immersiveness of the experience:
Continuity of surroundings: The user must be able to look around in all directions and have continuity of the environment.
Conformance to human vision: Visual content must conform to elements that allow humans to understand their environments, so that, for example, objects in the distance are sized appropriately to our understanding of their size and distance from us. Motion parallax ensures that our view of objects changes appropriately as our perspective changes.
Freedom of movement: It’s important that the user can move about normally within the confines of the environment. That capacity can be achieved in room-scale VR and dedicated VR rooms but requires complicated hardware for stationary VR and is impossible for seated VR.
Physical interaction: A user should be able to interact with objects in the virtual environment similarly to the way they do with real life ones. Data gloves, for example, can allow the user to make motions like pushing or turning to interact with objects in a natural way – turning a doorknob or picking up a book.
Physical feedback: The user should receive haptic feedback to replicate the feel of real-world interaction. So, for example, when a user turns a doorknob, they not only replicate the movement but experience the feeling of having that object in their hand.
Narrative engagement: The user should have the ability to decide the flow of the narrative. The environment should include cues that lead the user to create interesting developments.
3D audio: For immersiveness, VR environments should be able to replicate natural positioning of sounds relative to people and objects in the environment and the position of the user’s head.