1. Unit of Visually Impaired People, https://dx.doi.org/121451Italian Institute of Technology, 16147 Genua, Italy
2. Department of Psychological Sciences, Birkbeck, University of London, London, WC1E 7HX, UK
3. Department of Cognitive Sciences, Psychology, Education and Cultural Studies, University of Messina, 98122 Messina, Italy
4. Robotics Brain and Cognitive Sciences, https://dx.doi.org/121451Italian Institute of Technology, 16147 Genua, Italy