The importance of dependencies for polarisation and reasoning
PBS Departmental Seminar Series
Issue polarisation describes a state where citizens in a society move away from each other on a particular issue – for example, people may harden their views in both directions on abortion rights, economic policy, and more. In this talk, we consider a Bayesian model that builds on perceived dependencies. According to the model, when presented with conflicting testimony from two source groups, Bayesian agents should update towards the position of the group they deem to be more independent in terms of the factors that influence their testimony, meaning those who disagree about which group that is should polarise. In a pre-registered experiment, we find support for this model, as we can experimentally create polarisation by manipulating dependency perceptions.
To see if the intuitions of the model are appropriate, we survey citizens from the UK and the USA to gauge their dependency perceptions of in- and out-group members. In both countries, we find that, using a novel scale instrument, real-world partisans (Labour, Conservative, Republican, and Democrat) perceive their party’s supporters to be more independent than the opposing party’s supporters, with large average effect sizes (d = 0.87 UK, d = 0.82 US), suggesting the conditions are in place for such polarization to occur in the real world. We conclude the talk by considering limitations to the current work and future directions for the polarisation project.
Dr Jens Koed Madsen is Assistant Professor of Psychology in the Department of Psychological and Behavioural Science at LSE. He interested in how belief and behaviour impact democratic stability, information fragility, discrimination, and environmental sustainability. Specifically, Jens researches how people update their beliefs about the world when they see new information and how they use their understanding of the world to guide their behaviour.
In addition, he uses computational modelling techniques to understand how people may respond to political, economic, or information interventions. For example, how can we ensure democratic stability and have high-quality information systems while protecting freedom of speech?
To explore these questions, he uses a mixture of qualitative and quantitative methods (eg, interviews, Bayesian modelling, and agent-based modelling), experimental designs, and formal models to gauge how people adapt when their environment and social context changes (to explore how legislative, social, or systemic changes impact people’s beliefs and behaviour).
His work includes topics like environmental sustainability (eg, fisheries and poaching) and how information systems work (eg, echo chamber formation and the impact of credibility). He leads the ‘Decision-making In Complex Environments’ (DICE) group and teaches modules on cognitive psychology (PB201), research apprenticeships (PB312), social and public communication (PB404), and more.
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