Dominique Fréard, who holds a PhD in psychology and ergonomics and is based in our Department, made a significant contribution to a research article published in the *International Journal of Human Computer Interaction* («The Descent of Pluto: Interactive dynamics, specialisation and reciprocity of roles in a Wikipedia debate»). Co-authored with Télécom ParisTech and the LORIA and ICAR (CNRS) laboratories, this article presents a methodology for understanding and analysing user roles within interactive social networks (Online Epistemic Communities – OECs). Article available online: http://www.sciencedirect.com/science/article/pii/S1071581915001469#
