“…A few other groups follow machine learning approaches to train the classifier embedded in the BCI. These techniques range from linear classifiers (Babiloni et al, 2001;Obermaier, Müller and Pfurtscheller, 2001), to compact multi-layer perceptrons and Bayesian neural networks (Anderson, 1997;Roberts and Penny, 2000), to variations of LVQ (Kalcher et al, 1996), to local neural classifiers (Millán, 2002;Millán et al, 2002b). Most of these works deal with the recognition of just 2 mental tasks (Roberts and Penny, 2000;Babiloni et al, 2001;Obermaier, Müller and Pfurtscheller, 2001), or report classification errors bigger than 15% for 3 or more tasks (Kalcher et al, 1996;Anderson, 1997).…”