Immersion is a state of being so focused on a specific problem or experience that there are no distractions. Blocking out distractions makes it possible to stimulate the senses to tap imagination, provide new experiences, and increase a person's knowledge or awareness. Immersion can be achieved in part by the illusion of reality, whether that reality is familiar or some new, plausible but unfamiliar place (inside a protein molecule, flying over Mars) and in part by merely engaging the senses, delighting the imagination and holding the user's attention much as theater does.
Engaging, immersive environments can be created without HMDs, however. Video projection and visual displays alone may engage the user. The important visual elements are an appropriate resolution and update rate suitable for the particular task or experience and activities that are interesting to watch or invite the user's participation.
Immersion can be enhanced by the use of 3D sound to convey a greater sense of urgency, danger, excitement, or suspense. This sound may contribute to telepresence by appearing to emanate from different locations as objects move, and as the participant moves.
Tactile and force feedback devices as well as movement platforms may be used to add to the user's immersive experience. These devices allow the user to be physically part of the virtual world, controlling and manipulating the environment in real time with "immediate" results. The user may navigate through the space, select and move objects, open doors, and change parameters and features within the environment. These technologies, particularly tactile feedback, have far to go to simulate reality, but they offer the user an anchor in the virtual world that contributes to the sense of being there.
Preparation for designing immersive environments may include work in cognitive and behavioral psychology and human factors testing to provide insight into how people think, work, and interact in their environments; system analysis and communication skills to aid in identifying the entities, tasks, and relationships in the world to be created; training in the arts (film, graphic design, music) to engage the user and convey meaning; and knowledge of the available technologies (including data structures and algorithms) most appropriate for designing the particular environment. Designers of immersive environments must be able to integrate technology and task requirements with human factors effectively to minimize distractions and maximize features which enhance the user's focus.