Brain-Computer Interfaces describe the process of decoding control commands for machines by analysing brain activity. The demonstrator, developed by the department for Cognitive Assistants of the German Research Centre for Artificial Intelligence (DFKI), shows a simple interface for the control of a light bulb realised with a Muse brain sensing headband. The interaction principal is simple: Put on the headset, direct your thoughts focused in one direction and the bulb brightens up. Relax and let your thoughts wander – it gets darker.