Understanding crowd behaviour : simulating situated individuals

This thesis seeks to answer the question: Which mechanisms underlie crowd behaviour patterns? As a first step in the process to find an explanation for the mechanisms that underlie behaviour patterns, literature will be studied (chapter 2). There exists a lot of literature on crowd phenomena, mainly from a practical perspective. Practitioners are experience-driven and only rarely act in a way that is informed by the latest results of crowd research. At the same time, however, science often does not provide the systematic knowledge that practitioners need, in spite of the existing body of crowd research. Modern crowd research provides empirically-based description of crowd behaviour. Altogether, these studies identify a number of influence factors that are supposedly relevant for crowd behaviour (e.g. density, power structure). However, studies that describe why and how these factors exert their supposed effects remain scarce. The explanations provided so far tend to apply only in specific types of situations, predominantly disorder or emergency situations. Disorder studies focus on explanations in the social context, whereas emergency studies focus on explanations in the physical context. Nevertheless, three important general insights can be drawn from modern crowd research: • Crowd behaviour is generated by individuals, i.e. agency is at the individual level (and not at the group level). • Crowd behaviour is context dependent (context includes both the physical and social environment). • Crowd behaviour is dynamic: there is a continuous interaction between individuals and the environment over time. Given these insights, one cannot help but notice that the provided explanations do not incorporate the way in which individuals process information and choose behaviour. Consequently, reference to theories from cognitive sciences is rarely made in crowd research. Given the current state of knowledge and the fact that controlled experiments on crowds cannot be performed, two research needs are identified: First, the need for a theoretical model that reflects the dynamic interplay between individuals and their environment and second, the need for a method that allows for testing this theory. The development of the crowd model CROSS satisfies these two requirements.