基于稳态视觉诱发电位的脑机接口元素尺寸和间距工效学研究

针对基于稳态视觉诱发电位(SSVEP)的脑机接口系统，该文开展了屏显刺激界面元素尺寸和间距对识别效率和用户体验影响的工效学实验研究。该工效学实验使用红色正方形作为频闪刺激元素，刺激元素位于上、下、左、右等4个位置，自变量包含尺寸和间距两个因素。因素1为尺寸即正方形边长，分为100px，150px，200px3个水平；因素2为间距即元素中心与界面中心的垂直/水平距离，分为200px/400px，300px/600px，400px/800px3个水平。因变量为任务的完成时和失败次数。实验后开展主观评价，基于ISO 9241可用性标准，使用李克特7分量表对界面的满意度进行评分。工效学实验结果显示：元素尺寸对识别效率有显著影响，边长尺寸为200px的刺激元素识别效率最高，元素间距对识别效率没有影响。主观评价结果显示：元素间距对用户满意度有显著影响，刺激元素的紧凑(200px/400px)或疏远(400px/800px)都会导致满意度的下降，300px/600px间距水平的满意度最好，尺寸对用户满意度没有显著影响。该研究从设计工效学角度出发，发现了刺激界面元素尺寸、间距分别对脑机接口系统效率、用户满意度具有影响，研究结论对于规范脑机接口界面设计，提升脑机接口系统效率有重要的指导意义和借鉴价值。

Ergonomic Study on Element Size and Spacing of Brain Computer Interface Based on SSVEP

For the SSVEP-BCI, an ergonomic study is carried out on the effects of stimulation interface element size and spacing on recognition efficiency and user experience. In this experiment, the red squares are used as the stimulation elements. The squares are located on the upper, lower, left and right positions. The independent variables include two factors: size and spacing. Factor 1 (size) is the side length of the square, which is divided into three levels: 100px, 150px, and 200px; Factor 2 (spacing) is the vertical/horizontal distance between the element center and the interface center, which is divided into three levels: 200px/400px, 300px/600px, and 400px/800px. The dependent variables are the completion time and the number of failures of the tasks. Subjective evaluation is carried out after the experiment. Based on ISO 9241 usability standard, Likert 7-point scale is used to score the participants’ satisfaction of the interfaces. The results of the ergonomics experiment show that the element size has a significant impact on the recognition efficiency, the stimulation element with side length of 200px has the highest recognition efficiency, while the element spacing has no impact. The subjective evaluation results show that element spacing has a significant impact on user satisfaction. The compactness (200px/400px) or alienation (400px/800px) of stimulating elements will lead to the decline of satisfaction. The satisfaction of 300px/600px spacing level is the best, while the size has no impact. From the perspective of design ergonomics, it is found that the size and spacing of stimulating interface elements have an impact on the efficiency of SSVEP-BCI system and user satisfaction respectively. The research conclusion has guiding and reference value for standardizing the design of SSVEP-BCI and improving the efficiency of SSVEP-BCI system.