Director of research at INRAe, Guillaume Deffuant is one of the pioneers of opinion dynamics modeling (Deffuant model). He is interested in the relationship between the cognitive properties of agents and collective behavior in terms of opinion dynamics, radicalization or properties of actor networks. He also conducts research into the epistemology of modeling and viability theory.

Network-based approach to environmental decision-making and allocating emission responsibility

We live in an age of information abundance but know little about how this influences our opinions or attitudes. A common expectation is that people consulting numerous pieces of information, well balancing the different sides of an issue, will adopt a moderate attitude about the issue. We claim that this expectation is deceitful and suggest that, on the contrary, people tend to get extreme and dogmatic. The cause for this extremization is a hardening confirmation bias—when their attitude gets more extreme, people get more likely to ignore information that differs from their views. Our claim is supported by simulations of two fundamentally different computational models of an agent consulting information and holding a hardening confirmation bias. For both models, the initially moderate attitude of the agent tends to get extreme when the agent consults abundant unbiased information, while it remains moderate when consulting limited information. We analyze the extremization pathways displayed in the models and discuss how our results may affect views on polarization and on the role of online media.