Online discussions are the essence of many social platforms on the Internet. These platforms are receiving increasing interest because of their potential to become deliberative spaces. Many studies have proposed approaches to measure online deliberation and to evaluate which are the best design principles for deliberative online platforms. However, little research has focused on how deliberation in online platforms is affected by the arrival of events like the emergence of new topics or the modification of platform features. In this article we present a methodology to detect events that affect online deliberation in online discussions. Our results on Menéame, the most popular Spanish social news site, show that a change in how discussions are shown to the user, from a linear to a hierarchical conversation view, significantly enhanced deliberation. In particular we observe that this type of interface induced argumentative structures of online discussion.

This work is supported by the Spanish Ministry of Economy and Competi-tiveness under the Maria de Maeztu Units of Excellence Programme (MDM-2015-0502) and the EU project D-CENT (FP7/CAPS 610349).