1 Brain-Computer Interfaces Lab, Research Centre for Information and Communications Technologies (CITIC-UGR), Department of Signal Theory, Telematics and Communications, University of Granada, Granada, Spain.
2 BCI Lab Kleve, Faculty of Technology and Bionics, Rhine-Waal University of Applied Sciences, Kleve, Germany.
3 g.tec Medical Engineering GmbH, Schiedlberg, Austria.
4 Artificial Intelligence Department, Donders Institute, Radboud University, Nijmegen, Netherlands.