  Although cooperation is central to the organisation of many social systems,
relatively little is known about cooperation in situations of collective
emergency. When groups of people flee from a danger such as a burning building
or a terrorist attack, the collective benefit of cooperation is important, but
the cost of helping is high and the temptation to defect is strong. To explore
the degree of cooperation in emergencies, we develop a new social game, the
help-or-escape social dilemma. Under time and monetary pressure, players decide
how much risk they are willing to take in order to help others. Results
indicated that players took as much risk to help others during emergencies as
they did under normal conditions. In both conditions, most players applied an
egalitarian heuristic and helped others until their chance of success equalled
that of the group. This strategy is less efficient during emergencies, however,
because the increased time pressure results in fewer people helped.
Furthermore, emergencies tend to amplify participants initial tendency to
cooperate, with prosocials becoming even more cooperative and individualists
becoming even more selfish. Our framework offers new opportunities to study
human cooperation and could help authorities to better manage crowd behaviours
during mass emergencies.
