All for One

In the case of the recent IMF protest, the sheer number of arrests made in one day reflects the potentially large impact of group behavior. If individually isolated, most protestors would not have acted out enough to warrant an arrest. A group, however, often pushes individuals into performing uncharacteristic behaviors. "People tend to conform to the behavior of a crowd," explains Berkowitz. "It worked historically in things such as lynch mobs, but it can work more positively too. If there's a flood and everyone is going down to the riverbanks to throw sandbags on the levy, you are more likely to pitch in."