Science has discovered why pedestrians don't crash all the time: we have a kind of radar that allows us to anticipate the behavior of others.
The behavior of groups of humans, just like that of other animals, follows very specific rules that physics can try to explain. When you line up in a queue, or walk down the street, there are many so-called "self-organizing" attitudes - mostly unconscious - that you naturally enact.
The last IG nobel awards ceremony was intended to reward two curiously parallel research studies on pedestrian flow.
The IG nobel prize for physics went to the study on why pedestrians don't collide, while the one for kinetics went to the research that reveals why pedestrians sometimes do collide.
Pedestrian Collision Avoidance Radar
The study of pedestrian flow behavior is of crucial importance in the field of transportation, as it allows the prediction and management of the behavior of large masses of people, enabling the design of increasingly comfortable and safe transportation solutions.
While some phenomena present potentially dangerous aspects, such as large crowds that can cause serious accidents, there are some objectively virtuous and scientifically detectable natural behaviors that "help" pedestrian mobility.
Among these, the natural tendency to create two-way columns along the sidewalks of cities. According to the study that earned a well-deserved IG nobel for physics to the Dutch-Italian research team that conducted the experiment, we have a kind of innate "anti-collision radar".
The experiment proved that pedestrians spontaneously change their trajectory when another pedestrian gets too close or seems to cross their path, and did so by considering individuals as "particles".
The theoretical premise of the study is in fact that "if physics can explain the behavior of molecules, which closely resembles that of human groups," then it can probably be used to explain the behavior of "human molecules" as well.
After studying more than 5 million pedestrians in different circumstances and environments, and using a massive statistical dataset of experimental observations, scientists at several universities have developed a statistical model that defines the "anti-collision" mechanisms of pedestrians.
The model is so precise that it is able to account for specific dynamics such as acceleration avoidance and axis displacement, which are typical behaviors we engage in to avoid collisions with other pedestrians.
The research team is now working to determine which stimuli can "turn on" the innate anti-collision mechanism that allows us to walk down the street without colliding with other people.
The ability to anticipate the moves of others
A counterbalance to the research on pedestrian anti-collision radar is an almost entirely Japanese study recently published in Science Advance, which has been awarded the IG nobel for kinetics.
The study, titled "Mutual Anticipation May Aid Self-Organization in Human Groups," looked at two distinct classes of pedestrians: one very distracted by a cell phone, the other decidedly attentive to the path.
This type of experiment aims to move beyond the purely physical approach to the issue, seeking to pair it with close observation of empirical data.
Some very recent observations, in fact, "have shown that inter-individual interaction is essentially anticipatory in nature, rather than purely physical." In short, a closer observation of human dynamics would lead to the conclusion that pedestrian flows are not based on the perception of the position of others, but on the anticipation of the movements of others.
What surprised the researchers the most, is that people distracted by the cell phone and those concentrated showed the same difficulty in intercepting and anticipating the movements of other pedestrians.
Distracted pedestrians, continues the study, tend to slow down the general speed of the flow, and disturb the natural formation of lines in two directions: the distraction, is the conclusion of the research, affects the ability to anticipate the moves of others. And it would be precisely on anticipation, which is based our ability to walk between other people without constantly colliding with them.