A common assumption in traditional supervised learning is the similar probability distribution of data betweenthe 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 covariateshift-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 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.
- Adaptive learning ·
- Transductive learning
- · Covariate shift-detection ·
- Brain–computer interfaces
Raza, H., Cecotti, H., Li, Y., & Prasad, G. (2015). Adaptive learning with covariate shift-detection for motor imagery-based brain–computer interface. Soft Computing, 20(8), 3085-3096. https://doi.org/10.1007/s00500-015-1937-5