Experiencing Virtual Reality: The Impact of Motion Parallax and Binocular Disparity on Presence, Cybersickness, and Restoration
The main goal of virtual reality devices is to provide virtual environments where users experience a high level of presence, less cybersickness and suitable for many applications. One of the main applications that has attracted much attention recently is related to restoration. Experiencing a naturalistic virtual environment provides the opportunity to recover from mental and physical fatigue related to modern lifestyle. Given that virtual reality immersion is predominantly achieved by simulating a visual world, it might not be surprising that most factors that affect presence, cybersickness, and restoration concern the visual quality provided by virtual reality devices. The illusory nature of being in a virtual environment is highly mediated through simulating two prominent depth cues, binocular disparity and motion parallax. Given the importance of these two depth cues, this thesis aims to investigate the role of motion parallax and binocular disparity in the sense of presence, cybersickness, and restoration. In Chapter 2, I investigated the contribution of motion parallax and binocular disparity to the sense of presence. The results of Chapter 2 demonstrated a reduction in participants' subjective feeling of presence when motion parallax was compromised. Chapter 3 examined the effect of motion parallax and binocular disparity to the extent of experienced cybersickness in a nauseating virtual environment. Results revealed an equal contribution of both depth cues to the amount of experienced cybersickness. Finally, in Chapter 4, I compared the restoration effects of a virtual environment that contains plenty of nature elements, such as trees and plants, to the pictorial representation of the same environment. The results showed that participants who completed their restoration session in the middle of the virtual nature exhibited a significant improvement in stress and mood. The results of this thesis shed more light on important contributing factors to the above-mentioned topics. Understanding and Resolving problems related to cybersickness and presence will pave the path for virtual reality applications such as restoration to be more accessible and pleasant for users.