Reproducing Symmetry Breaking in Exit Choice under Emergency Evacuation Situation using Response Threshold Model

摘要

When people evacuate from a room with two identical exits, it is known that these exits are often unequally used, with evacuees gathering at one of them. This inappropriate and irrational behavior sometimes results in serious loss of life. In this paper, this symmetry breaking in exit choice is discussed from the viewpoint of herding, a cognitive bias in humans during disaster evacuations. The aim of this paper is to show that the origin of symmetry breaking in exit choice is simple herd behavior, whereas many models in the literature consider the exit choice decisions either as panic or rational behavior. The evacuation decision model, based on the response threshold model in biology, is presented to reproduce human herd behavior. Simulation with the evacuation decision model shows that almost all agents gather at one exit at some frequency, despite individual agents choosing the exit randomly.