Numerous studies over the last century have found evidence and understood conditions in favor of a wisdom of crowd phenomenon. However, it is less clear whether social influence increases or diminishes the accuracy of the crowd. In this presentation, we study the impact of social influence on wisdom via the celebrated French-De Groot opinion dynamics model. Social influence arises from the expertise of individuals, their self-appraisal bias, and the topology of their interactions. We determine conditions under which social influence improves or undermines the crowd accuracy. We identify an inherent fragility in crowd wisdom, when individuals rely upon biased assessments of accuracy instead of true accuracy in assigning interpersonal influence.

Fabio Fagnani got his Laurea degree in Mathematics from the University of Pisa and Scuola Normale Superiore of Pisa in 1986 and the PhD in Mathematics from the University of Groningen in 1991. He has been Assistant Professor of Mathematical Analysis at the Scuola Normale Superiore during 1991-1998, and in 1997 he held a Visiting Professor position at MIT. Since 1998 he is with the Politecnico of Torino where he is currently (since 2002) Full Professor of Mathematical Analysis. In the period 2012-2019, he has been the head of the Department of Mathematical Sciences of Politecnico di Torino. His current research interests are on the broad topic of dynamics and control over networks: opinion dynamics, inferential distributed algorithms, epidemic models, network games and learning dynamics in games, social and economic applications. He has published over 60 refereed papers on international journals and 50 over peer-reviewed conference proceedings. In 2017 he was the recipient of the Petar Kokotovic distinguished professorship from the University of California at Santa Barbara (UCSB). In 2019-2020 he got a Leverhulme visiting professorship at Royal Holloway University of London. He is currently Associate Editor of IEEE Transactions on Automatic Control and member of the international program committee for the events NECSYS