Effortless passive BCIs for healthy users

While a BCI usually aims to provide an alternative communication channel for disabled users who have difficulties to move or to speak, we focused on BCIs as a way to retrieve and use information about an individual's cognitive or affective state without requiring any effort or intention of the user to convey this information. Providing only an extra channel of information rather than a replacement of certain functions, such BCIs could be useful for healthy users as well. We describe the results of our studies on neurophysiological correlates of attention, workload and emotion, as well as our efforts to include physiological variables. We found different features in EEG to be indicative of attention and workload, while emotional state may be better measured by physiological variables like heart rate and skin conductance. Potential applications are described. We argue that major challenges lie in hardware and generalization issues.