By embedding opinions in a nonorthogonal topic space, a new model shows that a reinforcement mechanism reproduces extreme and correlated opinion states found in surveys.

Public opinion polarization is on the rise, as suggested by data collected across a variety of political and ethical issues. Opinions on different topics can also be correlated: Individuals advocating rights for transgender people, for example, are likely to also support same-sex couples. Strikingly, data shows correlations also between unrelated topics, such as rights of transgender people and the debate about whether the U.S. should build a wall at the border to Mexico.

In a new paper published in Physical Review X, an international team of scientists led by ISI Foundation’s researcher Michele Starnini proposes a simple model that reproduces such polarized ideological states, in which opinions are extreme and correlated with respect to different topics. Researchers develop a mathematical formalism in which opinions evolve in a multidimensional space, representing the relation between different topics.

The model reproduces a simple mechanism of social influence. People usually influence each other while discussing a certain topic. But when topics are controversial, the reinforcement mechanism proposed spills over a plethora of different topics. Two users advocating for transgender rights in a Twitter debate, for example, will reinforce their stances with respect to other controversial topics, such as the U.S. building wall with Mexico.

"Emergence of polarized ideological opinions in multidimensional topic spaces", Fabian Baumann, Philipp Lorenz-Spreen, Igor M. Sokolov, and Michele Starnini. Physical Review X, 20 January 2021