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January 16th 2025

Thomas Feliciani, NNC PhD student, has successfully defended his thesis titled "Divided Spaces and Divided Opinions: Modeling the Impact of Residential Segregation on Opinion Polarization". Thomas is currently applying his expertise at the Politecnico di Milano as a postdoctoral researcher Below, you can find a short excerpt from his dissertation.

The main conjecture I put forth in this dissertation is that two conditions facilitate the impact of ethnic residential segregation on attitude polarization and alignment. These conditions are: ( 1) social influence is local – thus, neighbors influence each other’s attitudes more than non-neighbors do; (2) ethnic membership moderates social influence – thus, ceteris paribus, two individuals belonging to the same ethnic group will influence each other’s attitudes differently than two individuals from different ethnic groups.
Several bits of evidence lend credit to the first condition (that social influence is local). To begin with, the people whom we can influence and who can influence us – that is, people in our social network – tend to live in our proximity. Geographic proximity facilitates encounters (Nilforoshan et al., 2023) and the formation of weak and strong ties (Balland, 2012; Daraganova et al., 2012; Hipp & Perrin, 2009). The importance of geographic proximity in network formation holds true in spite of widespread use of telecommunication and online social media (Backstrom et al., 2010; Mollenhorst et al., 2009; Morales et al., 2019)

December 5th 2024

Echo Teng Li, NNC PhD student, has successfully defended her thesis titled "Simulation Models of the Collective Consequences of Bounded Rationality in Opinion Formation in Networks". Echo will continue accompanying us in Groningen, working with fellow colleagues in her new Post-doc position! Below, you can find a short excerpt from her dissertation.

Human opinions emerge from a complex interplay of psychological, social, and environmental factors. This dissertation aims to model the dynamics of individual opinions at the micro level, influenced by cognitive limitations and socio-cultural contexts, and their role in shaping macro-level phenomena like social consensus and polarization. These micro-macro interactions are intricate, not only due to the multitude of heterogeneous individual agents involved, each of which is a complex system in itself, but also because they occur through various types of networks.
The theoretical frameworks developed in this dissertation facilitate an understanding of human opinion formation and dynamics. They are particularly well-suited to the analysis of how interactions among individuals with bounded rationality within social networks can lead to either the convergence or polarization of opinions at the societal level. These frameworks also hold the potential to be applied to other domains associated with opinion dynamics, such as opinions on public health responses to pandemics, or the adoption of new technologies. It is important to acknowledge that this dissertation represents a preliminary theoretical exploration of the collective consequences of bounded rationality in opinion formation in social networks.

October 26th 2023

Carlos de Matos Fernandes, NNC PhD student and former NNC Secretary, has successfully defended his thesis titled "In or out? The paradox of exclusionary mechanisms in keeping cooperation going". Carlos is now working as a Senior Data Scientist at DataFryslân. Below, you can find a short excerpt from his dissertation.

The question of who's in and who's out is not as straightforward as it seems when understanding the dynamics of exclusion in everyday life. This dissertation explores the intricate dynamics of cooperation and exclusionary mechanisms in social networks and groups by combining insights from formal theoretical modeling and empirical analysis, incorporating perspectives from multiple disciplines.
From the stability of social value orientations over time to the contextual influence on cooperation dynamics, this dissertation provides novel and nuanced views on the ways in which exclusion encourages cooperative behavior among individuals and – more importantly- when exclusion fails to promote cooperation. The research findings pave the way for future research in the field of exclusion, both theoretically and empirically, and highlight a downside for excluded defectors: If there is no “in” after exclusion, they may fall into a spiral of defection with a difficult road ahead for (if ever) reaching cooperation “at the end of the tunnel.”

January 20th 2022

Marijn Keijzer, NNC PhD student, successfully defended his thesis (cum laude) titled "Opinion Dynamics in Online Social Media". Marijn is currently a research fellow at the Institute for Advanced Studies in Toulouse (France). Please find a short excerpt from Marijn's dissertation below.

Models of social influence have been developed to understand opinion dynamics in complex systems (Flache et al., 2017). The literature of mathematical and computational models is rich and diverse, but little is known about the interrelations of, and empirical motivations for certain formalizations (Flache et al., 2017; Edmonds et al., 2019). In this young field, a plethora of models has been developed to describe similar processes or macro phenomena. While empirical research is the only method that will allow one to identify which explanations and models have verisimilitude (Popper, 2005), empirical research always departs from theory. Comparison of alternative theoretical explanations of a given phenomenon is needed to identify those aspects where competing theories di↵er. Empirical evidence can then serve to exclude problematic explanations (Carley, 2019; Keuschnigg, Lovsj o, & Hedstr om, 2017; Sobkowicz, 2009). For the sake of theory formation, insights in generalizability of documented mechanisms through model comparison is a useful frontier to be explored (Flache et al., 2017; Squazzoni, 2012). By learning more about our theoretical models, we collectively build a body of knowledge (Axtell, Axelrod, Epstein, & Cohen, 1996).
This dissertation aims to contribute to filling that void. The chapters in this book explore the empirical basis of formal models, exploit their power to develop a theory of online communication, present explanations for polarization and the diffusion of beliefs at the level of the entities that constitute them, and touch on the generalizibility and validity of those explanations.

April 15th 2021

Fleur Goedkoop, NNC PhD student, recently successfully defended her thesis titled "Involvement in Bottom-Up Energy Transitions: The Role of Local and Contextual Embeddedness". Fleur discussed her dissertation in an interview with the Dutch newspaper Trouw (link) and on the website of Topsector Energie (link). Please find a short excerpt from Fleur's dissertation below.

September 26th 2020

Recently, Marijn Keijzer was invited to share his views on the documentary The Social Dilemma (Netflix) on a Dutch national radio program. The documentary shows how big tech companies deal with data and how algorithms can influence behavior. Marijn discussed the relation between social media and polarization. Please find a link here (Dutch).

April 15th 2020

Marijn Keijzer and Carlos de Matos Fernandes wrote a piece in Review of Artificial Social Simulation Studies, entitled "No One Can Predict the Future: More Than a Semantic Dispute".

March 17th 2020

The Washington Post published an interesting article discussing agent-based models that visualize Why outbreaks like coronavirus spread exponentially, and how to “flatten the curve”. Albeit based on simple assumptions, these models indicate why social distancing matters.

For more information on agent-based models related to the COVID-19 (Corona) virus, please see the CoMSES forum or on Paul Smaldino's website.

You can run a NetLogo model in your browser here or inspect implications for policy here.

Orange = infected; purple = recovered; cyan = uninfected

September 2019

For those who missed it: all the materials from our workshop at Euro CSS Zürich (including the slides of Jan Lorenz' and David Garcia's presentations) are accessible through this webpage.

April 12th, 2018

This morning we briefly discussed the current state of scientific consensus around the Implicit Association Test (IAT). Some interesting sources: Limitations of the IAT shouldn't lead us to doubt the existence of implicit bias and a response to that argument. For a more in depth discussion of problems with the IAT, see this article.

November 30th, 2017

In the weekend after our meeting on Paul Collier's Foundations of economic failure article, NRC published a column on Collier's work >> link <<

June 1st, 2017

In July next year the quadrennial World Congress of Sociology, organised by the International Sociological Association, will take place in Toronto, Canada. On this conference there will be a session organised by Federico Bianchi and Flaminio Squazzoni on a topic that might be of interest to some members of the NNC. The title of the session is 'Social Behavior, Network Dynamics and Collective Outcomes in Complex Societies'. Deadline for abstract submission is September 30th.

>> Link to the session <<

>> Link to the ISA congress website <<