In order to deal with natural disaster risks, residents need to understand that serious situations exceeding our ordinary estimation can occur in the event of disasters. This study focuses on a cognitive bias in which risks of disaster events beyond the scope of our presumption are relatively underestimated. It developed a new type of flood hazard map providing reflective opportunities regarding assumptions of the map. It examined the effect of the hazard map for mitigating the cognitive bias about flood disaster through an experiment targeting 605 residents living near the Hijikawa river at Ozu-city in Ehime prefecture. The result showed that people tend more to recognize the possibility of occurrence of situations exceeding their own estimation in case of flood disaster in the Hijikawa river and reduce the tendency of the cognitive bias through reading the new type of flood hazard map than through an ordinary hazard map, indicating the importance of reflective opportunities.
How has the frequency distribution of domestic overnight leisure travel changed in the past few decades? In order to answer these questions, we analyze the time series change of travel frequency distribution for the Japanese from 1991 until 2011. We conclude that 1) the average annual travel frequency decreased for 20 years, 2) the zero frequency ratio is increasing, the difference of travel frequency between individuals is also increasing. Moreover, we propose the travel frequency model and explain this time series change by the changes of 3 effects (age, birth cohort and period in each prefectures) in order to understand the differences of travel frequency distributions. The results indicates that 3) the time series change in annual travel frequency can be explained by the changes in age composition and difference among birth cohorts, and 4) the change of zero frequency ratio can be explained by change of period effects and this occur only in rural areas.