Crowd Dynamics: Simulating Major Crowd Disturbances

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Crowd Dynamics: Simulating Major Crowd Disturbances. Valerie Spicer, PhD and Hilary Kim Morden , PhD Student Modelling of Complex Social Systems - MoCCSy. CCJA-ACJA October 2013. - PowerPoint PPT Presentation


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Crowd Dynamics: SimulatingMajor Crowd DisturbancesThis is a joint work with Piper Jackson, PhD, Andrew Reid, PhD Student, Vijay Mago, PhD and Vahid , PhDValerie Spicer, PhD and Hilary Kim Morden, PhD StudentModelling of Complex Social Systems - MoCCSyCCJA-ACJA October 2013Mathematical and computer modeling have numerous benefits when describing and simulating complex social interactions, such as occur with crowd dynamics and disturbances. Models can be used to:Explain phenomena - Via the examination of micro-level factors which give rise to macro-level phenomena such as we see in riots and other crowd disturbancesTest the premises of a theory allowing for the refinement of theory through the strict requirement of coding rules as well as providing the opportunity to test premises to examine whether they operate as expected or predictedrun experiments that test hypotheses in this case test hypotheses based on the micro level factors which give rise to crowd disturbancespredict by taking complicated inputs and processing them we can account for hypothesized mechanisms and then generate consequences as further predictionsto inform policy by varying the strength of concepts and determining outcomes based on changes in policyperformance simulation can perform tasks in a manner that mimics human reasoning and problem solving essentially, a simulation of human perception, decision-making, and social or ant-social interaction used to design new techniquestraining simulations can train people by providing a reasonably accurate and dynamic interactive representation of a given environment an example is flight simulators or riot simulations for police trainingdiscovery as a scientific methodology, simulations value lies principally in prediction, proof, and discovery. Using simulation for prediction can help validate or improve the model upon which the simulation is based. Prediction is the use that most people think of when they consider simulation as a scientific technique. But the use of simulation for the discovery of new relationships and principles is as important as proof or prediction. In the social sciences in particular, even highly complicated simulation models can rarely prove to be completely accurate. Nevertheless, social scientists have been successful in using simulation to discover important relationships and principles from very simple models. The simpler the model the easier it may be to discover and understand the subtle effects of its hypothesized mechanisms.




Computer scientists

Crowd management practitioner

Group CompositionFor this study, we formed a working group comprised of mathematicians, computer scientists, criminologists, and a crowd management practitioner. Integrated, multi-agency and multi-disciplinary groups allow the expertise of each discipline to come together informing the various aspects of the study helping to identify the factors relevant to the phenomenon under evaluation.2Group Process

There is an iterative process undertaken in creating and simulating computer models. In this study we started with a short lecture by the crowd management practitioner who discussed different aspects of crowd behaviour and environmental theories of crowd control. Group brain-storming followed whereby the different types of personal characteristics of individuals in crowds were discussed and agreement was reached on the three main types of behaviour potentials in crowds: disruptors, participant observers, and guardians. Event types were also brainstormed and agreement was reached on disturbance potential by event type: high risk, moderate risk, and low risk. Once the main factors were conceptualized the information moved into the hands of the mathematicians who created the initial model which was then simulated by the computer scientist. This model was then introduced to the social scientists who refined it based on theories of crowd behaviour. This process was repeated in an iterative manner until the model was stable and hypotheses testing could begin. 3

Literature reviewLeBon (1960) Group mind / psychological crowdsZimbardo (2007) De-individuation theoryMcPhail (1991) Crowd crystalsStott, Hutchison, & Drury (2001) Hooligans/ESIMForsyth (2006) 6 factors of collective behaviourMcHugh (2010) Emotions of body movementLeBon (1960). A crowd is a gathering of individuals of whatever nationality, profession, or sex, and whatever be the chances that have brought them together. A psychological crowd is a gathering of individuals, operating under a collective mind whereby the ideas and sentiments of all the persons in the gathering take on a single direction with loss of individual, conscious personality. This can occur simultaneously amongst a large number of individuals such as might occur at a national or patriotic event or may simply be the result of chance. In a psychological crowd individuals lose the qualities of personality and self that individuate them such as mode of life, occupation, character, intelligence. The result is a collective mind that makes them feel, think, and act in a manner quite different from that which they normally think and experience in a state of isolation. When the crowd begins moving towards organization, the conscious personality disappears and the thoughts/sentiments of the crowd turn in a single direction often away from the original purpose of the gathering. No specific number of individuals is required as one, strong-minded and singularly focused individual can begin this process with others getting caught up in the new purpose until it takes over the crowd. LeBon states that a law of mental unity then occurs which is a transitory, collective mind-state. Those most susceptible to the predisposing causes are first pulled in but then others get carried up into this state as well. While research shows that the behaviour of an individual under the influence of group mind is easy to identify in comparison to the behaviour of the individual, we still dont know quite why. Early theorists claimed that it was the result of being more alike in our unconscious allowing the phenomenon to occur. As LeBon states, in crowds, it is stupidity and not mother-wit that is accumulated.Zimbardo did a number of studies, the most famous being the Stanford Prison Study on this phenomenon, labelling it deindividuation. In a state of deindividuation the individual feels anonymous and a reduction or diffusion of responsibility. Heightened autonomic nervous system arousal occurs resulting in reduced self-awareness, minimal self-consciousness, disturbance in concentration and judgment and behavioural outcomes that mimic crowd crystals or leaders. Crowd crystals are individuals who, by their behaviour, draw attention to themselves or some event and prompt others to join them. Often crowd crystals are hooligans or other destructive types of persons. Their goal is to disrupt the crowd and cause a major disturbance. Hooligans can take an emotionally charged crowd and turn them into a mob. Mobs emerge from normal crowds or gatherings and are often regular persons such as yourself or myself. When the mob forms, research has shown that individuals are overwhelmed by their emotions and are no longer capable of controlling their own actions or applying their own inner normal measures of behaviour. Mobs, unless dispersed, will become volatile, unpredictable, and very capable of violence. They often move as one travelling from one place to another within the crowd causing major disturbances. Mobs may begin with high level of pro-social emotions such as we see in those rooting for a home team in a sporting event. These highly emotional states are readily transferred to anti-social behaviours when disappointment, anger, rage, a sense of unfairness or other negative emotions cause the transition to a destructive state of being. Riots are simply mobs on a grander scale where wanton and unrestrained behaviour violates the rules of civil and legal authority. Factors of collective behaviour have been seen consistently in studies related to major crowd disturbances. Forsyth as well as Forsyth and Donnelson found that collective behaviour is more likely to be seen in large rather than small groups where the individuals are in close proximity to one another though they can be widely dispersed if there is a method of communication such as cell phones or twitter posts. There is no set duration but these groups tend to form almost spontaneously and can be disbanded quickly think flash mob. Aberrant, anti-social, and unconventional behaviours will emerge regardless of whether the group is weakly joined together or highly cohesive. Collective behaviour does tend to move through crowds more quickly when they are formed for a cohesive purpose such as a sporting event where there are two opposing teams. Collective movement tends to be directed through movement, positioning, manipulation, gesticulation, verbalization, vocalization, and the physical orientation of the individuals. It was once thought that humans relied solely on facial expressions and verbal interaction to transmit information; however McHugh demonstrated that humans are capable of perceiving the emotion of a crowd from body motion and posture alone. Individuals will read the emotions of a crowd and correctly perceive what is happening very rapidly, allowing them to make a decision about their own behaviour or emotional state. Humans can read 6 emotions from a crowd stance including anger, disgust, fear, sadness, happiness and surprise and can do this in as little as 200 milliseconds with 90% accuracy. Inner emotions of the individual reading the crowd mood affect perception and response leading the individual to rapidly make a decision to join the crowd or move away from the crowd whether the individual actively recognizes this or not. Studies show that many do not actively perceive their understanding but rather get swept up in the emotion of the crowd. These factors help to explain how riots and other major crowd disturbances can so rapidly touch off. 4

Modeling ProjectSocial dynamics

Macro factors Fuzzy Cognitive Map (FCM)

Micro factors Cellular Automata (CA)

Threshold analysis: Major crowd disturbance

For our modeling project we took into account the prior research and determined that to account for the macro factors fuzzy cognitive map modeling would be the most efficient (those factors which affect the collective group or that occur due to the nature of the event or the location in which it is situated. Micro-level factors the behaviour of the individual and thus the group would be best simulated through a cellular automata model. We were interested in the levels of contextual factors that were necessary to create a major crowd disturbance. This is known as threshold analysis or more commonly as the tipping point. 5

Crowd PsychologyA people behaviour: DisruptiveB people behaviour: Observers ParticipantsC people behaviour: GuardiansBased on the understanding of psychological crowds, crowd crystals, hooligans, mobs, deindividuation, collective behaviour and how individuals interpret body movement we were able to break groups up into three distinct types of persons. Those who attend group events with the purpose of being disruptive. These are individuals who go to a sporting event not only to watch the event but to actively agitate the crowd towards a disturbance. These individuals become crowd crystals in the moments preceding a disturbance. Disruptive individuals are in the minority just as guardians are. Guardians will actively move against hooligans also attempting to act as crowd crystals but with pro-social goals. These are the kinds of individuals who attempt to stop crowd disruptions asking people to think about what theyre doing or who actively guard other people and physical locations. If you watched the videos of the 2011 hockey riot you can see there are individuals who attempt to protect others, who will mimic the behaviour of disruptors by attempting to make themselves as big as possible, even climbing up on podiums in an attempt to sway the crowds behaviour. The majority of people in the crowd are the observer/participant types. These individuals have a tendency towards either disruption or guardianship but can be swayed by the mood of the crowd and may move away from being one type of person to being the other type depending on circumstances. 6Macro FactorsEffective social control mechanismsPolice city transit Structured environmental factorsRoad design event locationUnfavourable situational factorsSuitable target podiums in the environmentUnstructured technological connectivityText messaging Twitter Facebook Volatile demographicsYounger people intoxication gender distribution High risk eventDivisive event non-family orientedMacro factors coded into the fuzzy cognitive map include effective social control mechanisms such as police, how transit is organized are they picking up at alternate stations, have they increased the number of trains moving people out of the cities, are police actively guiding people towards different stations or different routes out of the crowd area and so on. Structured environmental factors include factors which can only be slightly modified if at all such as roadways, transit stations, the location and staging of the event and so forth. Roads can be modified using barricades but cannot actually be changed. Buildings are included in this factor. All structured environmental factors are considered neutral in that they do not cause disturbances but simply exist. Unfavourable situational factors comprise of fixed factors such as podiums in the event area. These, while structural, can be used in negative ways such as crowd crystals or hooligans climbing on top of them to be more effective in sharing their vocalizations or instructions to others. Unstructured technological connectivity includes text messaging, cell phones, twitter posts and other social media posts. Anything that allows individuals in the crowd to transmit and receive messages rapidly. The advent of cell phone technology has changed the nature of crowd disturbances allowing them to more rapidly emerge as well as more quickly be avoided. Volatile demographics is related to the nature of the individuals attending the event with younger males being more likely to get caught up in a crowd disturbance especially if theyve been drinking or doing drugs that might lead to an increase in autonomic nervous system arousal compared to older individuals, young children, or families. High risk events include sporting events because they are divisive with an enemy or opposing team. These can cause much higher volatility than say a folk festival or childrens festival. We dont no...


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