title: Stationary common spatial patterns for brain-computer interfacing.
abstract: Classifying motion intentions in brain-computer interfacing (BCI) is a demanding task as the recorded EEG signal is not only noisy and has limited spatial resolution but it is also intrinsically non-stationary. The non-stationarities in the signal may come from many different sources, for instance, electrode artefacts, muscular activity or changes of task involvement, and often deteriorate classification performance. This is mainly because features extracted by standard methods like common spatial patterns (CSP) are not invariant to variations of the signal properties, thus should also change over time. Although many extensions of CSP were proposed to, for example, reduce the sensitivity to noise or incorporate information from other subjects, none of them tackles the non-stationarity problem directly. In this paper, we propose a method which regularizes CSP towards stationary subspaces (sCSP) and show that this increases classification accuracy, especially for subjects who are hardly able to control a BCI. We compare our method with the state-of-the-art approaches on different datasets, show competitive results and analyse the reasons for the improvement.
authors.affiliation: Machine Learning Group, Department of Computer Science, Berlin Institute of Technology, Franklinstr. 28/29, D-10587 Berlin, Germany. wojciech.samek@campus.tu-berlin.de
authors.forename: Wojciech
authors.initials: W
authors.lastname: Samek
authors.forename: Carmen
authors.initials: C
authors.lastname: Vidaurre
authors.forename: Klaus-Robert
authors.initials: KR
authors.lastname: Müller
authors.forename: Motoaki
authors.initials: M
authors.lastname: Kawanabe
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000502:physiology*; D002138:Calibration; D003627:Data Interpretation, Statistical; D004566:Electrodes; D004569:Electroencephalography / Q000706:statistics & numerical data; D004576:Electromyography; D004585:Electrooculography; D005528:Foot / Q000502:physiology; D006225:Hand / Q000502:physiology; D006801:Humans; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D015203:Reproducibility of Results; D014584:User-Computer Interface