Individual differences of P300 potentials lead to that a large amount of training data must be collected to construct pattern recognition models in P300-based brain-computer interface system, which may cause subjects' fatigue and degrade the system performance. TrAdaBoost is a method that transfers the knowledge from source area to target area, which improves learning effect in the target area. Our research purposed a TrAdaBoost-based linear discriminant analysis and a TrAdaBoost-based support vector machine to recognize the P300 potentials across multiple subjects. This method first trains two kinds of classifiers separately by using the data deriving from a small amount of data from same subject and a large amount of data from different subjects. Then it combines all the classifiers with different weights. Compared with traditional training methods that use only a small amount of data from same subject or mixed different subjects' data to directly train, our algorithm improved the accuracies by 19.56% and 22.25% respectively, and improved the information transfer rate of 14.69 bits/min and 15.76 bits/min respectively. The results indicate that the TrAdaBoost-based method has the potential to enhance the generalization ability of brain-computer interface on the individual differences.
P300 电位的个体差异导致基于该电位的脑-机交互系统需要每位被试的大量训练数据来构建模式识别模型，引起被试的训练疲劳，并可能由此导致系统性能降低。TrAdaBoost 是一种把源领域的知识迁移到目标领域，进而使目标领域能获得更好的学习效果的迁移学习方法。本研究针对 P300 电位的跨脑辨识问题，提出基于 TrAdaBoost 的线性判别分类算法和支持向量机，将同被试的少量数据训练的分类器与不同被试的大量数据训练的分类器按权重组成融合分类器。与只采用少量同被试数据或者混合不同被试数据来直接进行训练的传统学习方式相比，本文算法在少量样本情况下将准确率分别提高了 19.56% 和 22.25%，信息传输率分别提高了 14.69 bits/min 和 15.76 bits/min，有望提高脑-机交互系统对被试个体差异的泛化能力。.
Keywords: P300; TrAdaBoost; brain-computer interface; linear discriminant analysis classifier; support vector machine; transfer learning.