In May 2013, the iTunes and Google Play stores contained 23,490 and 17,756 smartphone applications (apps) categorized as Health and Fitness, respectively. The quality of these apps, in terms of applying established health behavior change techniques, remains unclear.

Collective decision making involves on the one hand individual mental states such as beliefs, emotions and intentions, and on the other hand interaction with others with possibly different mental states. Achieving a satisfactory common group decision on which all agree requires that such mental states are adapted to each other by social interaction. Recent developments in social neuroscience have revealed neural mechanisms by which such mutual adaptation can be realised. These mechanisms not only enable intentions to converge to an emerging common decision, but at the same time enable to achieve shared underlying individual beliefs and emotions. This paper presents a computational model for such processes. As an application of the model, an agent-based analysis was made of patterns in crowd behaviour, in particular to simulate a real-life incident that took place on May 4, 2010 in Amsterdam. From available video material and witness reports, useful empirical data were extracted. Similar patterns were achieved in simulations, whereby some of the parameters of the model were tuned to the case addressed, and most parameters were assigned default values. The results show the inclusion of contagion of belief, emotion, and intention states of agents results in better reproduction of the incident than non-inclusion.

• Videos were analyzed to examine which emergency communication strategies might reduce risk behaviors. • We believe this is the first video analysis relating emergency communications to evacuation behaviors. • Our analyses suggest that having staff guide people to exits is the most effective evacuation strategy. • Evacuation alarms were associated with more delayed responses than other communication strategies. • People filming the incident occurred more with alarms sounding and prerecorded messages might not prevent people filming the incident. • Compared to no communications, all emergency communication strategies were associated with running during evacuations. • Our main practical recommendation is to supplement traditional emergency alarms with guidance from staff.