Universität Konstanz, Konstanz, Germany.
Zukunftskolleg der Universität Konstanz, Konstanz, Germany.
PLoS One. 2020 Oct 29;15(10):e0241479. doi: 10.1371/journal.pone.0241479. eCollection 2020.
Virtual reality (VR) technology is commonly used in balance research due to its ability to simulate real world experiences under controlled experimental conditions. However, several studies reported considerable differences in balance behavior in real world environments as compared to virtual environments presented in a head mounted display. Most of these studies were conducted more than a decade ago, at a time when VR was still struggling with major technical limitations (delays, limited field-of-view, etc.). In the meantime, VR technology has progressed considerably, enhancing its capacity to induce the feeling of presence and behavioural realism. In this study, we addressed two questions: Has VR technology now reached a point where balance is similar in real and virtual environments? And does the integration of visual cues for balance depend on the subjective experience of presence? We used a state-of-the-art head mounted VR system and a custom-made balance platform to compare balance when viewing (1) a real-world environment, (2) a photo-realistic virtual copy of the real-world environment, (3) an abstract virtual environment consisting of only spheres and bars ('low presence' VR condition), and, as reference, (4) a condition with eyes closed. Body sway of ten participants was measured in three different support surface conditions: (A) quiet stance, (B) stance on a sway referenced surface, and (C) surface tilting following a pseudo-random sequence. A 2-level repeated measures ANOVA and PostHoc analyses revealed no significant differences in body sway between viewing the real world environment and the photo-realistic virtual copy. In contrast, body sway was increased in the 'low presence' abstract scene and further increased with eyes closed. Results were consistent across platform conditions. Our results support the hypothesis that state of the art VR reached a point of behavioural realism in which balance in photo-realistic VR is similar to balance in a real environment. Presence was lower in the abstract virtual condition as compared to the photo-realistic condition as measured by the IPQ presence questionnaire. Thus, our results indicate that spatial presence may be a moderating factor, but further research is required to confirm this notion. We conceive that virtual reality is a valid tool for balance research, but that the properties of the virtual environment affects results.
虚拟现实 (VR) 技术因其能够在受控实验条件下模拟真实世界体验而在平衡研究中得到广泛应用。然而，一些研究报告称，与在头戴式显示器中呈现的虚拟环境相比，在真实世界环境中平衡行为存在相当大的差异。这些研究大多是在十多年前进行的，当时 VR 仍在努力克服重大技术限制（延迟、有限的视野等）。在此期间，VR 技术取得了相当大的进展，增强了其产生存在感和行为真实性的能力。在这项研究中，我们提出了两个问题：虚拟现实技术现在是否已经达到了在真实和虚拟环境中平衡相似的程度？以及平衡的视觉线索整合是否取决于存在感的主观体验？我们使用了最先进的头戴式 VR 系统和定制的平衡平台来比较以下三种情况下的平衡：（1）真实环境，（2）真实世界环境的逼真虚拟副本，（3）仅由球体和棒组成的抽象虚拟环境（“低存在感” VR 条件），并作为参考，（4）闭眼条件。十名参与者的身体摆动在三种不同的支撑面条件下进行了测量：（A）安静站立，（B）在参考摆动的表面上站立，以及（C）按照伪随机序列倾斜表面。采用 2 水平重复测量方差分析和事后分析，发现观看真实世界环境和逼真虚拟副本之间的身体摆动没有显著差异。相比之下，在“低存在感”抽象场景中，身体摆动增加，并且随着闭眼进一步增加。结果在平台条件下保持一致。我们的结果支持这样的假设，即最先进的 VR 已经达到了行为真实性的程度，在逼真的 VR 中平衡与真实环境中的平衡相似。与逼真的条件相比，在抽象的虚拟条件下存在感较低，这是通过 IPQ 存在感问卷测量的。因此，我们的结果表明，空间存在感可能是一个调节因素，但需要进一步研究来证实这一观点。我们认为虚拟现实是平衡研究的有效工具，但虚拟环境的特性会影响结果。
