Max Planck Institute for Biological Cybernetics, Tübingen, Germany. christoph.kayser@tuebingen.mpg.de|Max Planck Institute for Biological Cybernetics, Tübingen, Germany. christoph.kayser@tuebingen.mpg.de|Max Planck Institute for Biological Cybernetics, Tübingen, Germany. christoph.kayser@tuebingen.mpg.de