Data_Sheet_1_A Hybrid Brain-Computer Interface Based on Visual Evoked Potential and Pupillary Response.docx

Brain-computer interface (BCI) based on steady-state visual evoked potential (SSVEP) has been widely studied due to the high information transfer rate (ITR), little user training, and wide subject applicability. However, there are also disadvantages such as visual discomfort and “BCI illiteracy.” To address these problems, this study proposes to use low-frequency stimulations (12 classes, 0.8–2.12 Hz with an interval of 0.12 Hz), which can simultaneously elicit visual evoked potential (VEP) and pupillary response (PR) to construct a hybrid BCI (h-BCI) system. Classification accuracy was calculated using supervised and unsupervised methods, respectively, and the hybrid accuracy was obtained using a decision fusion method to combine the information of VEP and PR. Online experimental results from 10 subjects showed that the averaged accuracy was 94.90 ± 2.34% (data length 1.5 s) for the supervised method and 91.88 ± 3.68% (data length 4 s) for the unsupervised method, which correspond to the ITR of 64.35 ± 3.07 bits/min (bpm) and 33.19 ± 2.38 bpm, respectively. Notably, the hybrid method achieved higher accuracy and ITR than that of VEP and PR for most subjects, especially for the short data length. Together with the subjects’ feedback on user experience, these results indicate that the proposed h-BCI with the low-frequency stimulation paradigm is more comfortable and favorable than the traditional SSVEP-BCI paradigm using the alpha frequency range.

基于稳态视觉诱发电位（SSVEP）的脑机接口（BCI）因其高信息传输率（ITR）、用户训练需求低以及广泛的主试适用性而备受研究。然而，该技术亦存在诸如视觉不适和“BCI 文盲”等不足。为解决这些问题，本研究提出采用低频刺激（12 类，0.8–2.12 Hz，间隔为 0.12 Hz）的方法，该法能同时诱发视觉诱发电位（VEP）和瞳孔反应（PR），以构建混合脑机接口（h-BCI）系统。分类准确度分别采用监督和非监督方法进行计算，并通过决策融合方法结合 VEP 和 PR 的信息以获得混合准确度。来自 10 位受试者的在线实验结果表明，监督方法的平均准确度为 94.90 ± 2.34%（数据长度 1.5 秒），非监督方法的平均准确度为 91.88 ± 3.68%（数据长度 4 秒），分别对应的信息传输率（ITR）为 64.35 ± 3.07 比特/分钟（bpm）和 33.19 ± 2.38 bpm。值得注意的是，对于大多数受试者，混合方法相较于 VEP 和 PR 实现了更高的准确度和信息传输率，特别是在较短的数据长度情况下。结合受试者对用户体验的反馈，这些结果表明，所提出的基于低频刺激的 h-BCI 方案相较于使用 α 频段的传统 SSVEP-BCI 方案，在舒适度和受欢迎程度方面更具优势。