The definition of Mixed Reality can be traced back to 1994, a research paper written by Paul Milgram and Fumio Kishino.
This was the first academic paper to use the term “Mixed Reality” in the context of computer interfaces. In the almost 25 years since, the paper has received more than 2600 citations, making it the most popular research paper to use the term, decrying more citations than most research papers in AR or VR.
Milgram and Kishino describe Mixed Reality as “ a specific subclass of VR-related technologies that involve the merging of real and virtual worlds.” More specifically, they say, Mr involves a blending of real and virtual worlds somewhere along the “reality-virtuality continuum” (RV), which connects fully real environments to fully virtual ones.
AV is a virtual world in which elements of the real world are included, just as AR is a real world with elements of the virtual image incorporated into it.
Mixed Reality covers the part of the continuum between the decidedly real environment and the decidedly virtual environment.
But it always involves combining elements of the real and virtual world, and therefore endpoints of continuity are not considered Mixed Reality.
Simply put, the VR experience displayed on a VR head-mounted screen that does not show a part of the real world is not an MR experience.
Similarly, looking at a real-world live video feed on a TV screen that does not contain any virtual images is not an MR experience either. But almost every screen that combines real and virtual images is a Mixed Reality experience.