1. Artificial and Mechanical Intelligence Research Line, Istituto Italiano di Tecnologia (IIT), Center for Robotics and Intelligent Systems, 16163 Genova, Italy
2. Machine Learning and Optimisation, The University of Manchester, Manchester M13 9PL, UK
3. iCub Tech Facility, Italiano di Tecnologia (IIT), Center for Robotics and Intelligent Systems, 16163 Genova, Italy