Bull Running May Help Scientists Predict Human Behavior Under Stress

According to Jorge Laval, a traffic theorist at the Georgia Institute of Technology who was not involved in the study, the findings could help researchers model better behaviors and help people avoid fires and other disasters. “I thought it was very interesting,” Jorge said.

For the uninitiated, the bull run is part of the annual festival, where participants run through narrow streets along with running animals. While this is a voluntary and somewhat contrived danger, Daniel Parisi of the Buenos Aires Institute of Technology, one of the study’s authors, says the events are real enough to paint a rare picture of how people behave in an attempt to avoid danger. Since the festival opened in 1910, about 16 people have died and hundreds more have been injured. Most of the deaths were from bull butting, the last of which occurred in 2009, but other injuries are usually from falls and collisions.

To collect data, Parisi and his colleagues set up a pair of cameras suspended over the streets of Pamplona to observe the action from a bird’s eye view. They recorded two runs in a row on festival days in 2019. Cameras recorded the speed and direction of each runner, as well as the density of the crowd.

The cameras show a group of people running slowly through the streets. As the bulls run closer, a large group of people runs past the camera in front of the animals. People jump to the side when the bulls overtake them.

Surprisingly, the data showed that the runners’ speed increased with increasing crowd density — up to a certain limit. This is the opposite of what researchers usually find when studying the flow of people or movement: usually, people slow down as the crowd gets denser.

The authors say the results may be related to the willingness of the runners to vary their speed at different stages of the competition. For example, in a crowded metro station, everyone wants to walk at a regular, steady pace; adding more people just slows everyone down. But on the streets of Pamplona, ​​the runners wait for the bulls, run quickly along the road, and then return to moderate speed again, creating a wave with a combination of density and speed around the animals.

Of particular interest in crowd dynamics, which can lead to more efficient management of various infrastructure, is the study of people in conditions of high numbers per unit area. One example of such a scenario is the flight of people from real danger, but, of course, it is difficult to analyze it experimentally. This is why the San Fermin Bull Run is an exceptional annual event where you can collect real data on people’s dynamics in extreme conditions. This kind of data is scarce and therefore very valuable.

In the end, the population density was the cause of the tragedy in Pamplona. When the crowd increased to one or two people per square meter, the maximum speed of the runners dropped sharply, often people collided and fell. Once the crowd exceeded two people per square meter, almost no one was able to maintain a speed above an easy jog (about 2 meters per second).

An accurate understanding of the speed limits imposed by crowds could help researchers build better pedestrian traffic patterns and improve evacuation in the event of fires and other emergencies, Parisi said.

“When people are stressed and running to save their lives, there is a good place with very low density where you can take advantage,” says Laval.

The best way to apply this information, he said, is to continue to develop policies and designs for buildings that disperse people and keep densities low, perhaps by expanding escape routes or limiting the number of people in the area from the start.

Laval and Parisi agree that it is best not to run or fuss in an emergency. In this case, the likelihood that you will get injured will be significantly reduced.