Department of Biomedical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
Comput Intell Neurosci. 2019 Jul 1;2019:9680697. doi: 10.1155/2019/9680697. eCollection 2019.
Recent studies on brain-computer interfaces (BCIs) based on the steady-state visual evoked potential (SSVEP) have demonstrated their use to control objects or generate commands in virtual reality (VR) environments. However, most SSVEP-based BCI studies performed in VR environments have adopted visual stimuli that are typically used in conventional LCD environments without considering the differences in the rendering devices (head-mounted displays (HMDs) used in the VR environments). The proximity between the visual stimuli and the eyes in HMDs can readily cause eyestrain, degrading the overall performance of SSVEP-based BCIs. Therefore, in the present study, we have tested two different types of visual stimuli-pattern-reversal checkerboard stimulus (PRCS) and grow/shrink stimulus (GSS)-on young healthy participants wearing HMDs. Preliminary experiments were conducted to investigate the visual comfort of each participant during the presentation of the visual stimuli. In subsequent online avatar control experiments, we observed considerable differences in the classification accuracy of individual participants based on the type of visual stimuli used to elicit SSVEP. Interestingly, there was a close relationship between the subjective visual comfort score and the online performance of the SSVEP-based BCI: most participants showed better classification accuracy under visual stimulus they were more comfortable with. Our experimental results suggest the importance of an appropriate visual stimulus to enhance the overall performance of the SSVEP-based BCIs in VR environments. In addition, it is expected that the appropriate visual stimulus for a certain user might be readily selected by surveying the user's visual comfort for different visual stimuli, without the need for the actual BCI experiments.
基于稳态视觉诱发电位（SSVEP）的脑-机接口（BCI）的最新研究已经证明了它们可用于控制虚拟现实（VR）环境中的物体或生成命令。然而，大多数在 VR 环境中进行的基于 SSVEP 的 BCI 研究采用了通常在传统液晶显示器环境中使用的视觉刺激，而没有考虑到渲染设备（用于 VR 环境的头戴式显示器（HMD））的差异。HMD 中的视觉刺激与眼睛的接近度很容易导致眼疲劳，从而降低基于 SSVEP 的 BCI 的整体性能。因此，在本研究中，我们在佩戴 HMD 的年轻健康参与者身上测试了两种不同类型的视觉刺激——图案翻转棋盘刺激（PRCS）和缩放刺激（GSS）。初步实验旨在研究每位参与者在呈现视觉刺激时的视觉舒适度。在随后的在线虚拟化身控制实验中，我们观察到基于用于诱发 SSVEP 的视觉刺激类型，个体参与者的分类准确性存在相当大的差异。有趣的是，主观视觉舒适度评分与基于 SSVEP 的 BCI 的在线性能之间存在密切关系：大多数参与者在他们更舒适的视觉刺激下表现出更好的分类准确性。我们的实验结果表明，在 VR 环境中，适当的视觉刺激对于增强基于 SSVEP 的 BCI 的整体性能非常重要。此外，预计通过调查用户对不同视觉刺激的视觉舒适度，可以很容易地为特定用户选择适当的视觉刺激，而无需进行实际的 BCI 实验。
