Emergence of cooperation as the impact of evacuee's solidarity

Evacuation simulation is an effective way for exercising an evacuation plan. Various situations that may arise can be examined by computer simulations. Studying a human behavior in evacuation simulation is important to avoid the negative effect that may occur. We propose an evacuation model: "Evacuee's Dilemma", inspired by Prisoner's Dilemma in Game Theory. This model aims to describe helping behavior among evacuees. Evacuees are facing a dilemma to choose cooperate behavior: helping others and escaping together; or defect behavior: rush to exit. The dilemma occurs because offering help to other evacuees requires a cost: sacrificing their own resources. Therefore, helping other evacuees might risk their own life. However, if an evacuee chooses not to help, then the abnormal evacuees might not be able to survive. Unless there are other evacuees who offer help to the abnormal evacuees. We introduce Averaged Systemic Payoff in the evacuee's decision making. Multi-Agent Simulations are conducted with various settings. Simulation results reveal an interesting collective behavior. Rational evacuees increase the cooperate behavior under an extreme short time availability to evacuate. Instead of mass panic, we observed that the collective behavior of cooperation emerged in an evacuation with a high time pressure. We found that Averaged Systemic Payoff is effective to control the cooperation among rational evacuees. We also studied the influences of Solidarity, Neighborhood Range, and time pressure to Averaged Systemic Payoff. This finding is useful to avoid the defect behavior in evacuation, which might emerge to panic stampede or any other dangerous crowd situation.