title: Polarisation and protest mobilisation around secessionist movements: an agent-based model of online and offline social networks
Creators: name: Chueca Del Cerro, Cristina
Publisher: name: University of Glasgow
Year: 2023

description: Secessionist movements are notorious for their abilities to mobilize people. Although these movements might use economic grievances or policy preferences to attract support, national identity remains at the core of every secessionist movement, justifying their right, as a nation, to become an independent self-governing state. As these divisions on the basis of national identity grow wider, animosity between groups grows, contributing to reducing social cohesion and escalating the political conflict. This thesis is interested in understanding the role national identity polarisation plays in the emergence of protests around independence movements. Much of the recent debate in political sciences has been regarding the role of social media’s filtering algorithms in the emergence of polarisation as well as the existence or prevalence of the so-called echo chambers. There is a lack of consensus around the extent to which social media filtering algorithms and online echo chambers promote polarisation and how this in turns affects protest mobilisation. This thesis proposes a social simulation approach to the topic of protest mobilisation dynamics from a political communication perspective to understand how national identity polarisation, through social network configurations and the media environment, contribute to the emergence of protest mobilisation in a context where secessionist movements are present. I have developed a theoretical agent-based model (ABM) of Social Identity and Protest Mobilisation (SIMPE) that simulates online and offline discussions of national identity and the emergence or absence of protests in order to answer the research question. This complexity science approach has the capacity to model the evolution and interaction between national identity polarisation and protest mobilisation, that is not possible with alternative methods. Moreover, using this simulation method allows for disentangling the mechanisms through which social media filter bubbles and individual social networks may contribute to the emergence of national identity polarisation and ultimately protest mobilisation. The Catalan secessionist movement has been used to ground and contextualise this research, theoretically and empirically. Data from the Catalan Centre of Opinion Studies (Centre d’Estudis d’Opinió; CEO) was used to inform the distribution of national identities in SIMPE, producing an abstract and an empirically-informed version of the simulation. This thesis therefore contributes to the politics and social simulation literatures providing a theoretical framework that systematically explores how national identity polarisation can promote protest mobilisation. The simulation explicitly models social networks in the form of a multilayer multiplex network of online and offline social networks while also simulating social media filtering algorithms. In doing so, it is able to explore the extent to which each of these factors promote national identity polarisation and protest mobilisation. Additionally, this thesis contributes by providing not only a theoretical model but also an empirically-informed agent-based model of protest which has been a long-standing demand in the field of social simulation. I found that the initial social network setup conditions had a large impact on the emergence of national identity polarisation as well as protest mobilisation. In particular, homophily-based networks, composed of a majority of like-minded individuals, produced greater national identity polarisation compared to random networks, composed of diverse views. This was especially the case in the presence of social media filtering algorithms, selectively exposing agents to national identity supportive information. These results emphasise the importance of selective exposure by social media filtering algorithms and one’s social networks in the process of national identity polarisation. Therefore it provides further evidence for the negative effects of social media platforms for social cohesion and how they can promote polarisation and protest mobilisation. Overall, this thesis was able to provide a plausible and possible explanation of how, through the interactions of social media platforms and social networks, the polarisation of national identity promotes the emergence of protest. These findings evidence the role that social networks and social media platforms have on our behaviours as well as suggest new research avenues using social simulation methods in combination with political science theories.