Modeling Public Fear Under the Information Environment of Emergencies as COVID-19 and Wars

Under the recent pandemic of corona-virus disease COVID-19, people have repeatedly reacted to the information concerning the spread of the epidemic, which has flooded in our society throughout the whole time. By using the statistical data obtained in Japan, a mathematical model treating the relation between the information environment and the public reaction caused by fear is proposed. The input quantities for this model are the time-varying environment of information on the COVID-19 together with the amount of public communication or the amount of information search on the COVID-19 via the SNS. Between those two quantities, we introduce three variables such as the amount of information released by the news media every day, the novelty of information, and the extent of people’s surprise to the information. Regarding the amount of information, we use the real quantity observed in Japan, whereas the novelty of information is related to the so-called oblivion function by which the extent people forget the information in the past is given. Two types of oblivion function, the power-law type and the exponential type, are introduced. On the other hand, the extent of people’s surprise by the information on COVID-19, which is determined so as to make sure the consistency of the model as a whole, has revealed to have sharp peaks at the earliest time of the pandemic, and the beginning of every emergent-state declarations over eight times. Such a reaction around the people’s surprise is due to the emotional contagion in the fearful field of information environment. To compare the time-dependent trend of those variables to the other cases of social events, we have introduced the case of Ukraine-Russia conflict reported in Japan since 1 January 2022. The people’s surprise in this case has revealed that people astonished only at the first time of the conflict, without any surprise after that even the novelty of information has been high. Discussion was made on the sources about the difference regarding the people’s surprise between the cases COVID-19 and Ukraine-Russia conflict.