1. Department of Computer and Systems Sciences, Stockholm University, Sweden and Department of Computer Science, Aalborg University, Denmark
2. Department of Computer Science, Aalborg University, Denmark
3. Department of Media Technology and Interaction Design, KTH Royal Institute of Technology, Sweden
4. Department of Computer and Systems Sciences, Stockholm University, Sweden
5. Department of Media Technology, Södertörn University, Sweden
6. Department of Computer Science, Harvard University, United States