Adaptive learning with covariate shift-detection for motor imagery-based brain-computer interface

A common assumption in traditional supervised learning is the similar probability distributionof data between the training phase and the testing/operating phase. When transitioning from the training to testing phase, a shift in the probability distribution of input data is known as a covariate shift. Covariate shifts commonly arise in a wide range of real-world systems such as electroencephalogram-based brain–computer interfaces (BCIs). In such systems, there is a necessity for continuous monitoring of the process behavior, and tracking the state of the covariate shifts to decide about initiating adaptation in a timely manner. This paper presents a covariate shift-detection and -adaptation methodology, and its application to motor imagery-based BCIs. A covariate shift-detection test based on an exponential weighted moving average model is used to detect the covariate shift in the features extracted from motor imagery-based brain responses. Following the covariate shift-detection test, the Communicated by D. Neagu. B Haider Raza [email protected] Hubert Cecotti [email protected] Yuhua Li [email protected] Girijesh Prasad [email protected] 1 School of Computing and Intelligent Systems, Intelligent Systems Research Centre, Ulster University, Londonderry, UK 2 School of Computing, Science and Engineering, University of Salford, Manchester, UK methodology initiates an adaptation by updating the classifier during the testing/operating phase. The usefulness of the proposed method is evaluated using real-world BCI datasets (i.e. BCI competition IV dataset 2A and 2B). The results show a statistically significant improvement in the classification accuracy of the BCI system over traditional learning and semi-supervised learning methods.