António Fonseca presented his PhD thesis on the 6th of April 2015, at ISCTE-IUL, entitled “Mecanismos de Popularidade e Difusão de Informação em Redes Sociais” (in Portuguese). The jury was composed by Ricardo Fonseca, Helder Coelho, Ernesto Costa, António Firmino da Costa, Luis Antunes, Pedro Lind, and Jorge Louçã (supervisor).
This research investigates the mechanisms of formation of popularity in society, assuming that popularity is generated though processes of information diffusion.
A static model of the distribution of popularity by various entities is here proposed and validated. It is demonstrated that it ts a probabilistic distribution of exponential growth of popularity. Complementarily, two dynamic models are proposed, representing the evolution of popularity. The first model, named Ramication Model, is an exogenous impact model tracing the prole of the typical evolution of popularity triggered by a single external event. The second one, called Epidemic Model, represents the process of popularity formation when arising from internal dissemination of messages within a community. All models are validated with experimental data.
A case study, concerning communication data collected during the
2011 elections in Portugal, allowed measuring the influence of popularity, generated through Social Communication, on opinion dynamics. Two sociophysics opinion dynamics models, based on the Brownian Model of Influence, and on the Social Impact Theory, were used to represent theoretically and quantitatively the dynamics of public debate in this period.
One of the most relevant results of the research concerns the understanding that the long term increasing of some entity’s popularity, as a result of communication processes between individuals, is independent from the entity subjective qualities, and it depends mainly from the communication processes being used.