1. Laboratory of Synthetic, Perceptive, Emotive and Cognitive Systems (SPECS), Center of Autonomous Systems and Neurorobotics, Universitat Pompeu Fabra (UPF), Barcelona, Spain
2. Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
3. Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands
4. Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy