Synchronized violin players reveal the uniqueness of human networks

There is rarely time to write about every cool scientific story that comes our way. This year, therefore, we are once again holding a special series of twelve days of Christmas with posts highlighting one science story that fell through the cracks in 2020, every day from December 25th to January 5th. Today: experiments in synchronization in a network of violinists have shown that people can drown distractions and wrong communication, the better to stay in step.

A August 2020 study, published in Nature Communications, uses a model of violin synchronization in a network of violinists, revealing that there are ways to drown distractions and miscommunication.

An unusual experiment with 16 violinists trying to synchronize their playing while wearing sound-canceling headphones has yielded interesting results, according to an August 2020 article published in Nature Communications. The study concluded that human networks differ fundamentally from other networks in terms of synchronized behavior because of our decision-making ability. This can lead to better models for complex human behavior, with applications in diverse areas such as economics, epidemiology, politics, traffic management, and the dissemination of misinformation.

Preliminary studies have been conducted on synchronization in human behavior, particularly with regard to bridge dynamics. As we have reported before, people walking on a sliding bridge will instinctively adjust their pace to suit the swinging motion of the bridge as it moves sideways diagonally. This is familiar to anyone who has tried to walk on a fast moving train and needs to find a fixed position while the train staggers from side to side. But a bridge exacerbates the problem and leads to additional small lateral oscillations that amplify the swing. The result is a positive feedback loop (the technical term is ‘synchronous lateral excitation’).

If you get a large number of people who fit the bridge’s movement, the swing can become dangerous, like the Millennium Bridge when it first happened in June 2000. About 90,000 people crossed the bridge on the first day, with about 2,000 people on it at any given time, and the movement of the crowd gave rise to significant shaking and swaying.

Over time, the pedestrians accidentally synchronized with each other, causing the bridge to wobble even worse. The spontaneous synchronization of the crowd was similar to what happens with the strongly synchronized flame of fireflies or the shooting of neurons in the brain. Londoners have been nicknamed “Wobbly Bridge”. Officials closed it after just two days, and the bridge closed for the next two years until appropriate changes could be made to stop the swing.

The phenomenon was also observed in stock market brokers, according to a 2011 study, which found that the daily instant messaging patterns of traders are closely related to their level of synchronous trading. Conclusion: “The higher the traders’ synchronous trading, the less likely they are to lose money at the end of the day,” the authors wrote. Applied mathematician Steven Strogatz of Cornell University conducted synchronization experiments with crickets in soundproof boxes.

Moti Fridman – a physicist at Bar-Ilan University in Israel and co-author of the violinists – also has a long interest in synchronization, having published studies on large synchronized laser networks and, on a smaller scale, the unusual coupling that explain why rubbing one wine glass gives a tone and causes oscillations on other wine glasses. For violin studies, he collaborated with Elad Shniderman, a music student at Stony Brook University in New York, as well as colleagues at Bar-Ilan and the Weizman Institute of Science.

Sixteen violinists took part in a network experiment in which they were connected to a computer system, and heard only the sound of the computer.
Enlarge / Sixteen violinists took part in a network experiment in which they were connected to a computer system, and heard only the sound of the computer.

Chen Damari

Previous studies have largely involved simple networks where each person (or node) is connected to each other person. In a more complex network, the number of connections between each person may vary, and there may also be delayed messages between them that may prevent the transition to a synchronized state. Like Fridman et al. wrote in their paper: “Research on network links or connectivity has focused primarily on all-to-do connectivity, while current social networks and interactions between people are often based on complex link configurations.”

The violinists who participated put on sound-suppressing headphones and started repeating the same repetition of the music without looking or listening to the other players. They could only rely on what they heard through the headphones, which were connected to a computer system. The researchers then set up intermittent delays in signals between paired violinists, varying the delays and combinations of violinists. This is called a “frustrated situation”, and most network models assume that each node in such a frustrated state will try to find a middle ground between all the different inputs.

Instead, Fridman et al. found that the players responded by adjusting their playing, speeding up or slowing down to better match their fellow violinists. “Human networks behave differently than any other network we have ever measured,” Fridman told The Jerusalem Post. “In a state of frustration, they do not seek a ‘remedy’, but ignore one of the inputs. This is a critical phenomenon that changes the dynamics of the network. Human networks can change their inner structure for a better solution. to achieve what is possible in existing models. ‘

This is similar to a phenomenon known as the “cocktail party effect”: the ability of people to choose one thread of conversation between a cacophony of chatter in a crowded room. But the effect has so far not been incorporated into network synchronization studies. The next step is to take the experiment online and try to synchronize hundreds and thousands of violinists over the internet.

Building better models of complex human behavior would have an impact on a variety of fields, such as better controlling epidemics – these days that are of particular concern, given the ongoing coronavirus pandemic – and spreading false information on social media. occur (‘fake news’). “Our results are also related to any network where every node in the network has decision-making capability, such as autonomous cars, or the introduction of AI in our highly connected world,” Fridman told Inside Science. “Our model can predict the dynamics of such systems with high accuracy, beyond what was previously possible.”

DOI: Nature Communications, 2020. 10.1038 / s41467-020-17540-7 (on DOIs).

List by Chen Damari

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