When New York's World Trade Center looked as if it was about to collapse after being hit by two planes on the morning of Sept. 11, thousands of people in the offices of the Twin Towers did not break into panic. Instead, they reacted anxiously, moving slowly and leaving the building in a calm manner.
Jens Krause has listened to hundreds of eye witnesses recounting these moments and the people's reactions confirm his research findings about social behavior. "Panic is the very last thing that sets in when a situation escalates," the biologist from the Institute of Freshwater Ecology at Berlin's Humboldt University says. It was only when the towers collapsed that total chaos and mayhem broke out.
Mass hysteria always happens gradually and Krause believes it can be prevented through intervention. By means of computer models and experiments, he researched how best to diffuse a situation by moving test subjects to an alternative location as quickly as possible. Krause claims that the study could help overcrowded museums channel visitors through exhibitions efficiently, and could contribute towards designing effective evacuation plans for buildings.
And his research results are of global relevance: the number of large events is rapidly increasing and with them the inherent dangers that big crowds entail. In the past century alone, 4,000 people died in crowd crushes caused by mass panics and more than 10 times as many suffered injuries.
At concerts and other large events the general rule is to place security personnel and stewards at entrances and exits to prevent problems. Krause found though, that this rule does not apply in every case, especially if a building has to be evacuated quickly.
Krause's team analyzed the behavior of 200 volunteers in an arena with a diameter of 50 meters. The arena could only be evacuated safely and quickly if the security personnel were posted in the corners of the arena or in the middle of the crowd. Only the personnel, and not the members of the crowd, knew that the aim was to evacuate those in the venue to a "safe place" on the edge of the arena. Krause illustrated his findings through computer animations.
He also found that there is no need for security personnel to be dressed in an identifiable uniform. As long as those in the crowd are aware that there is someone who will lead them to safety, the theory works.
The experiment worked quickly from the very start: the security personnel moved very determinedly and firmly to the edge of the arena. Although there was no verbal communication, the other members of the crowd recognized the resolute behavioral characteristics of the personnel and followed them intuitively. "Behavior alone is enough for the crowd to recognize if somebody has certain information," Krause concludes in the study, which he will publish shortly.
Krause's research also demonstrates that unsuspecting individuals can benefit from the knowledge of a single person. In emergency situations this can save lives. Krause found that one supervisor to 20 people was an ideal ratio for the theory to work. If there were more supervisors, the group had a tendency to divide up, but not evacuate any faster.