VR vs Real Environments
When we move through real environments, we have no problem with maintaining awareness of our position despite the fact that our relationship with surrounding objects constantly changes. Even when we limit our perception (for example, by closing our eyes), the ability to estimate our position remains functioning.
This is, however, not the case in virtual reality. Most virtual reality systems are not designed for full physical motion and thus lack cues that are necessary for automatic special updating. From a practical standpoint, it is not likely that motion platforms and large free-space walking areas will ever see a widespread use. Researchers have successfully demonstrated that the mere illusion of self-motion (“circular vection”) can provide a similar benefit as actual self-motion.
Creating the Illusion of Self-Motion
One study investigated effects of spatialized sound rotating around the stationary listener on the illusion of self-rotation. Results showed that auditory vection alone is not sufficient for providing a realistic experience of physical rotation. It was only when rotating sound fields were paired with biomechanical vection induced by a rotating platform that performance was significantly improved.
In addition to physical stimulus properties, cognitive mechanisms such as ecological relevance and presence evoked by a virtual environment can also enhance visually induced self-motion illusions (vection). A stable, natural 3D scenes help observers accept visual motion as self-motion.
Finally, researchers have discovered that physical vibrations of the observer’s seat can enhance the vection illusion. In their experiment, simple (on/off) vibrations were used without any relation to movement velocity or direction. Not all participants said that these simple vibrations were sufficient for creating the illusion of vection, which suggests that more accurate vibrations could have yielded better results.