Title:
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Extremist viewpoints in opinion dynamics: relative agreement versus relative disagreement
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In our lifetime there has been a marked increase in the number of ways in
which people can communicate. This greater connectivity presents an added
urgency for developing a solid understanding of the spread of deviant
attitudes, particularly when they manifest as violent outbursts. How an
otherwise moderate and rational populace can devolve to extremity through
self-organisation is a question that must be answered if we hope to understand
the underlying causes of atrocities that follow from extremism. That is the
main question this dissertation hopes to tackle, specifically with a greater
degree of realism and much less reliance on artificial manipulation than is
currently present in the accepted literature of Opinion Dynamics. One such
attempt at answering these questions is the Relative Agreement model, where
agents are paired in order to exchange information about their own opinion. In
this model, populations exhibit examples of real world convergences provided
a number of initial parameters are specified.
This thesis seeks to challenge and improve upon the accepted notion of the
Relative Agreement model after finding fault with the published literature
through the first known attempt at replication of its findings. Once a
discussion of the discrepancies has been completed, a thorough analysis of the
model is presented along with a number of suggested improvements to
increase the capability and usefulness of the model. This examination is then
followed by changing the population from a fully connected graph to a
tuneable Klemm-Eguiluz social network to examine the model's properties
under more realistic constraints. With this addition it was found that when
agents are highly clustered, alternative population behaviours are inhibited,
contrary to real world data. As a result, it is noted that the Relative Agreement
model must be significantly improved upon, if it is to be applied to real world
study.
Once this analysis has been completed, a new model is presented, building on
the Relative Agreement model and taking inspiration from Social Judgement
Theory in psychology, creating the Relative Disagreement model. In this
model, a disagreement dynamic is added removing the al1ificial need for pre-existing
extremist agents and fixed uncertainties. It is then demonstrated that
the Relative Disagreement model is able to exhibit all of the original
behaviours, even with the most clustered of agent populations. Thus it can be
seen that the Relative Disagreement model presented in this thesis represents a
significant step forward in the understanding of extremist opinion spread and
formation, the former having up until now required specific parameters to be
set and the latter phenomenon being largely ignored in the field of Opinion
Dynamics.
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