Knowledge of how groups escape in emergency situations is crucial to human safety but how can experiments on crowd emergency evacuation be performed under genuine settings?
The solution, as conceived by a group of researchers from the University of the Philippines Diliman, is to study the behavior of mice under duress.
According to Drs. Caesar Saloma, Gay Jane Perez, Catherine Ann Gavile, Jacqueline Judith Ick-Joson and Cynthia Palmes-Saloma, experimenting with mice avoids serious ethical and legal issues that arise when dealing with unwitting human participants while minimizing concerns regarding the reliability of results obtained from simulated experiments using actors.
Mice were trained separately and their individual escape times were measured over several trials. It was found that mice learned quickly to swim towards an exit, with the fastest escape times recorded within the first four trials.
The trained mice were then placed together in the pool and allowed to escape. No two mice were permitted in the pool beforehand and only one could pass through an exit opening at any given time.
Groups of trained mice initially escaped seven and five times faster than their corresponding control groups of untrained mice at pool occupancy rate ρ of 11.9 percent and 4 percent, respectively.
Trained mice were capable of faster evacuation for three reasons. First, they had better recognition of the available pool space and took shorter escape routes to an exit. Second, they were less likely to form arches that blocked an exit opening. Third, they utilized the two exits efficiently without preference.
Aside from escaping more quickly, trained groups also exhibited self-organized queuing, i.e., they continued to escape even without an apparent leader-coordinator. This happened even if self-organized queuing, a collective behavior, was not experienced during individual training.
The researchers said that this is because the trained mice were able to coordinate with each other to a certain degree possible. Coordination develops when group members are able to commit information-driven actions instead of blind copying or non-copying (e.g. aimless swimming).
In contrast, queuing was absent in untrained groups in which mice were prone to wall seeking, aimless swimming and/or blind copying that produced circuitous escape routes, biased exit use and clogging.
The experiments also reveal that faster and less costly group training at ρ = 4%, yielded an average individual escape time that is comparable with individualized training. However, group training in a more crowded pool (ρ = 11.9%) produced a longer average individual escape time.
The paper of Saloma et al was published on PLOS ONE. (Click here to download.)