Imitative (herd) behaviour in direction decision-making hinders efficiency of crowd evacuation processes

Humans use social information to improve their decisions in scenarios that involve uncertainty. Previous research has shown that this social influence can have positive or negative outcomes depending on the context of decision and characteristics of the system. A particular scenario where the social information matters is the collective escape where behaviour of others could be used as an extra source of information and thus, influence the decision-making. The question is whether there could be any benefit for escaping human crowds to display imitative tendencies (or the so-called ‘herd’ behaviour) in their decision making. Here, we investigate this question in relation to exit direction decision-making through extensive computer simulation analyses. Using parameteric models of decision making, we increased the imitative tendency of (behaviourally) homogenous crowds on a continuum, simulated the escape process and outputted measures of system efficiency. We examined a broad range of simulated scenarios in terms of the shape of the environment, exit visibility and spatial distribution of exit capacities. Results showed that for none of the scenarios we tested, the escaping crowd could benefit from amplified tendencies to imitate peers. Our numerical analyses suggested that, at least when familiar with escape routes, there is no rationale for blindly following the direction choices of the crowd in emergency scenarios. Strong tendency to copy direction choices of the crowd could substantially hinder the process of evacuations and increase the risk of casualty. These findings have potential implications for evacuation training guidlines. They provide insights into how individuals should be guided/instructed to conduct themselves in case of an emergency in order to facilitate and optimise the evacuation process. A question for future research is how imitation (herding) in other aspects of escape behaviour (such as movement initiation or adapting (changing) direction choices) can influence the system.