Ideology, communication and polarization

Abstract

Ideologically committed minds form the basis of political polarization, but ideologically guided communication can further entrench and exacerbate polarization depending on the structures of ideologies and social network dynamics on which cognition and communication operate. Combining a well-established connectionist model of cognition and a well-validated computational model of social influence dynamics on social networks, we develop a new model of ideological cognition and communication on dynamic social networks and explore its implications for ideological political discourse. In particular, we explicitly model ideologically filtered interpretation of social information, ideological commitment to initial opinion, and communication on dynamically evolving social networks, and examine how these factors combine to generate ideologically divergent and polarized political discourse. The results show that ideological interpretation and commitment tend towards polarized discourse. Nonetheless, communication and social network dynamics accelerate and amplify polarization. Furthermore, when agents sever social ties with those that disagree with them (i.e. structure their social networks by homophily), even non-ideological agents may form an echo chamber and form a cluster of opinions that resemble an ideological group. This article is part of the theme issue 'The political brain: neurocognitive and computational mechanisms'.

Keywords: communication; cultural dynamics; opinion dynamics; social network dynamics.

Figure 1.

A schematic of the psychological model of ideological thinking. Note. Each agent consists of an interpreter and a memory. A circle is a cognitive unit that represents a proposition; the figure assumes five propositions constitute an ideology. Activation of each unit indicates the level of agreement that the agent has for the corresponding proposition. C_i represents the associations between the propositions for that agent, while M_(t−1)i represents the pre-existing associations between opinions and sources. e_ti = the agent's interpreted input at time t; s_t = the agent's source attribution at time t; M_ti = their memory representation at time t; E_ti = their episodic memory that binds the attributed source and interpreted input; o_ti = the agent's opinion retrieved by cuing memory by self-representation, s_oi; d_i = a weight given to the prior memory; T designates transposition. (Online version in colour.)

Figure 2.

Trajectories of each of the four cognitive styles. Note. The y-axis indicates (output)a, the dot product of the output with an ideology. Each graph shows the results of 50 random inputs for 100 agents of each type. 1, ideological interpreter + ideologically ego-involved; 2, ideological interpreter; 3, ideologically ego-involved; 4, non-ideological. (Online version in colour.)

Figure 3.

Trajectories of opinion dynamics with communication. Note. The y-axis indicates the extent to which each agent's output is aligned with the ideology. In this plot, time 0 is that of the initial random inputs to the system, and times 1–50 plot the opinions expressed by agents: 1, ideological interpreter + ideologically ego-involved; 2, ideological interpreter; 3, ideologically ego-involved; 4, non-ideological.

Figure 4.

Trajectories of opinion dynamics with relational mobility. Note. The y-axis indicates the extent to which each agent's output is aligned with the ideology. Each graph shows the results of an example of 100 interacting agents of each type: 1, ideological interpreter + ideologically ego-involved; 2, ideological interpreter; 3, ideologically ego-involved; 4, non-ideological. (Online version in colour.)