Supplementary data for the paper 'Assessing the influence of visual stimulus properties on steady-state visually evoked potentials and pupil diameter'

Steady-State Visual Evoked Potentials (SSVEPs) are brain responses measurable via electroencephalography (EEG) in response to continuous visual stimulation at a constant frequency. SSVEPs have been instrumental in advancing our understanding of human vision and attention, as well as in the development of brain-computer interfaces (BCIs). Ongoing questions remain about which type of visual stimulus causes the most potent SSVEP response. The current study investigated the effects of color, size, and flicker frequency on the signal-to-noise ratio of SSVEPs, complemented by pupillary light reflex measurements obtained through an eye-tracker. Six participants were presented with visual stimuli that differed in terms of color (white, red, green), shape (circles, squares, triangles), size (10,000 to 30,000 pixels), flicker frequency (8 to 25 Hz), and grouping (one stimulus at a time vs. four stimuli presented in a 2×2 matrix to simulate a BCI). The results indicated that larger stimuli elicited stronger SSVEP responses and more pronounced pupil constriction. Additionally, the results revealed an interaction between stimulus color and flicker frequency, with red being more effective at lower frequencies and white at higher frequencies. Future SSVEP research could focus on the recommended waveform, interactions between SSVEP and power grid frequency, a wider range of flicker frequencies, a larger sample of participants, and a systematic comparison of the information transfer obtained through SSVEPs, pupil diameter, and eye movements.

稳态视觉诱发电位（Steady-State Visual Evoked Potentials, SSVEPs）是指通过脑电图（electroencephalography, EEG）可检测到的、对恒定频率持续视觉刺激产生的大脑响应。SSVEPs为人类视觉与注意力机制的研究深化，以及脑机接口（brain-computer interfaces, BCIs）的技术开发提供了关键支撑。目前仍有待厘清的核心问题是：何种类型的视觉刺激可诱发最强效的SSVEP响应。本研究探究了颜色、尺寸与闪烁频率对SSVEP信噪比（signal-to-noise ratio）的影响，并辅以通过眼动仪（eye-tracker）采集的瞳孔光反射（pupillary light reflex）测量数据。实验共招募6名被试，向其呈现的视觉刺激在颜色（白色、红色、绿色）、形状（圆形、正方形、三角形）、尺寸（10000至30000像素）、闪烁频率（8至25Hz）以及呈现方式（单次单个刺激，或以2×2矩阵同时呈现4个刺激以模拟脑机接口应用场景）等维度存在差异。实验结果表明，尺寸更大的刺激可诱发更强的SSVEP响应，同时伴随更显著的瞳孔收缩反应。此外，研究还发现刺激颜色与闪烁频率之间存在交互效应：红色在较低频率区间的诱发效果更佳，而白色则在较高频率区间表现更优。未来的SSVEP相关研究可聚焦于以下方向：确定推荐使用的最优刺激波形、探究SSVEP与电网频率的交互效应、拓展闪烁频率的测试范围、扩大被试样本量，以及系统对比通过SSVEP、瞳孔直径与眼动指标所获取的信息传输效率。