Opinion dynamics and collective risk perception: An ABM model of institutional and media communication about disasters

The behavior of a heterogeneous population of individuals during an emergency, such as epidemics, natural disasters, terrorist attacks, is dynamic, emergent and complex. In this situation, reducing uncertainty about the event is crucial in order to identify and pursue the best possible course of action. People depend on experts, governmental sources, the media and fellow community members as potentially valid sources of information to reduce uncertainty, but their messages can be ambiguous, misleading or contradictory. Effective risk prevention depends on the way in which the population receives, elaborates and spread the message and together these elements result in the collective perception of risk. The interaction between individuals' attitudes toward risk and institutions, the more or less alarmist way in which the information is reported and the role of the media can lead to risk perception that differs from the original message, as well as to contrasting opinions about risk within the same population. The aim of this study is to bridge a model of opinion dynamics with the issue of uncertainty and trust in the sources, in order to understand the determinants of collective risk assessment. Our results show that alarming information spreads more easily than reassuring one, and that the media play a key role in this. Concerning the role of the internal variables, the simulation results show that risk sensitiveness has more influence on the final opinion than trust towards the institutional message. Also, the role of different network structures seems negligible, even on two empirically calibrated network topologies, thus suggesting that knowing beforehand how much trust the citizens place in their institutional representatives and how reactive they are to a certain risk might provide useful indications for designing more effective communication strategies in times of crises.