Abstract
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, government 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 a 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 plays a key role in this. Concerning the role of internal variables, our simulation results show that risk sensitiveness has more influence on the final opinion than trust towards the institutional message. Furthermore, the role of different network structures seemed to be negligible, even on two empirically calibrated network topologies, thus suggesting that knowing beforehand how much the public trusts their institutional representatives and how reactive they are to a certain risk might provide useful indications to design more effective communication strategies during crises.
Highlights
In order to understand collective risk assessment and its emerging macro-e ects, we developed an agent-based model in which heterogeneous agents form opinions about risk events depending on information they receive from the media, institutions and their peers
We distinguish between simulation experiment, in which there is only one source of information about the risk, i.e., the institution, and simulation experiment, in which the presence of media is introduced. For both experiments we aimed to study how interaction between individuals’ internal states, information coming from or di erent sources, and topology a ects the dynamics of collective risk assessment
In Figure we show the behavior of the final average opinion as a function of I in complex topologies, i.e., ring, Erdös-Rényi random network, Watts-Strogatz small-world network, and real e-mail network
Summary
In six scientists were put under investigation for allegedly giving false and fatal reassurances to the public a few days ahead of the earthquake (Hall ). They were members of the “National Commission for the Forecast and Prevention of Major Risks” (Commissione Grandi Rischi), a governmental body which was asked to provide advice about tremors and earthquakes in the area. The fact that these scientists and their spokesperson issued a statement reassuring the population made many people feel safe enough not to leave their houses a er the initial shocks on the same night.
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