Immersion, Presence, and Engagement

Immersion

Immersion is often described as a state, formally defined by Witmer and Singer (1998) as, “perceiving oneself to be enveloped by, included in, and interacting with an environment that provides a continuous stream of stimuli and experiences”. We can consider immersion as a concept that focuses on sensory input and cognitive reaction: the environment is real because the objects in it look and sound the way their counterparts in reality do. This relies primarily on the user’s perception of the objective level of sensory fidelity provided by the VR/AR system. A digital pond with digital frogs croaking matches the knowledge we have of real ponds with real frogs croaking, so we are more easily immersed in said environment.
Because sensory immersion relies on audio, visual, and cognitive components of the game, we must allow users the flexibility of a system that makes the user feel both familiar and aware of their environment. This can be seen in visual, haptics, and audio design, but also in finer levels of onboarding or accessibility settings that help our users engage with said digital reality in comfortable and meaningful ways.
A great way of understanding the difference between Immersion and Presence is that because of sensory immersion, VR/AR headsets are currently the most immersive devices we currently have. This is due to the application's potential for stimuli that continually attempt to replicate that of the physical world through ways that are extensive, matching, surrounding, vivid, interactive, and plot informing (Slater and Wilber, 1997). Mobile games (or books for that matter), therefore, can be seen as the least immersive. However, a mobile game (or book) could end up offering a better sense of presence than a VR/AR experience due to the suspension of disbelief for the experience itself - because presence is informed through the psychological and physiological state of the user. As defined by Jason Jerald in The VR Book, "[Presence is] an awareness in the moment of being immersed in a virtual world while having a temprorary amnesia or agnosia of the real world and the technical medium of the experience."

Presence

Presence can be defined as a “sense of being there,” or a sense of spatially being in a digital place or virtual environment even when one is physically in another (Minsky 1980; Heeter 1992; Witmer and Singer 1998). Presence, therefore, is the psychological response that is triggered by external factors that leads to a perception of believability. This could be more easily said as a “suspension of disbelief” in the users’ surroundings. It can be analogized as the believability once gets from walking down the halls of a Haunted House, even though you are consciously still aware that the entirety of the environment is fictionally constructed.
We must consider environmental fidelity when speaking on presence and immersion simply because this is what consistently causes breaks in these two constructs, in both the literal (graphical fidelity) or metaphorical (content construction). Components we must consider in building up human perception within these digital environments can be found in both the optimization of the technical environment, as well as the infrastructure and interactions within the world. Because environmental fidelity inherently relies on the graphical fidelity of the hardware itself, and because we don’t want our users disoriented in the map of the world, we should be constructing our experiences so that users can feel physically comfortable, knowledgeable, and safe.

Engagement

Engagement is a very familiar term within games as a whole, and ubiquitous regardless of platform. However, I do want to call it out specifically within the construct of VR/AR as it is important to help your user within VR/AR technologies in a different way than most other platforms. Because your user isn’t just looking at a screen, but is literally teleported into a new and unfamiliar environment, VR/AR games require a distinct, heavy-handed usage of constraint to focus the player’s attention and interest in mechanisms that allow them to observe and interact with the digital environment.
Engaging with content in a knowledgeable and enjoyable way is important for both immersion and presence to be sustained. However because this is a new environment, everything must be overtly taught to the user - even simple things like walking around the environment or completing a valid action. We want our users to feel a sense of achievement in mastering gameplay, but we need to be incredibly thoughtful in delivering this knowledge in order for our users to do basic interactions.