中文摘要：

为提高基于P300的字符输入脑机接口系统的信息传输率，提出了一种交互式方案。基于视觉刺激强度增加会提高P300波峰的幅值这一原理，设计了根据受试者的脑电信号特征改变字符闪烁亮度的刺激模式，并与传统不变亮度的方式进行对比。实验结果表明，通过改变字符闪烁的亮度，该系统能够给予受试者实时的反馈信息，减少了正确识别字符所需要的刺激序列数，从而提高了P300字符输入系统的性能。

英文摘要：

To improve the information transfer rate of the P300 speller brain-computer interface system, an interactive scheme is presented. Based on the principle that increasing the visual stimulus intensity improves the peak amplitude of the P300 wave, a novel stimulus pattern, i. e. , character flashing with brightness changing according to the EEG signal of the subject is devised. The results indicate that, compared with the conventional invariant brightness pattern, the proposed stimulation pattern can give subjects a real-time feedback, thus the performance of the speller is effectively improved by a reduction of stimulus sequences needed for target detection.