Ensemble or pool: A comprehensive study on transfer learning for c-VEP BCI during interpersonal interaction

Abstract

BackgroundTo reduce calibration time of brain–computer interface (BCI) or even implement zero-training BCI, researchers have been studying how to effectively apply transfer learning in the field. In order to thoroughly investigate the performance of transfer learning in BCI and the key factors affecting transfer performance in the field, we carried out a comprehensive study. New methodIn general, transferring knowledge in BCI is implemented in two ways: ensemble or pool. In this work, we propose two different transfer approaches. One is to transfer the information of all channels as a whole from the source subjects to a target subject. The second approach is to transfer the information of corresponding channels between the subjects. A subject transfer framework is built by combining the two approaches with ensemble or pool. ResultsWe investigated the performances of eight implementations of this framework on a data set acquired by an interpersonal interaction (Chicken Game) experiment based on code-modulated visual evoked potential (c-VEP) BCI. The results show that transfer learning generally provides acceptable classification performance. Additionally, an in-depth analysis reveals that a target subject usually shares different brain signal distribution with different source subjects. In fact, this is a hypothesis usually implied by this kind of research. ConclusionsTransfer learning for c-VEP BCI can be qualified for reducing calibration time or starting the recognition of BCI without sufficient subjects’ own data. In addition, our finding suggests a solid validity of the hypothesis underlying transferring knowledge in BCI.