Understanding how a group of people splits

Tuesday, 2 February, 2021 - 00:00 to 23:30

Suprising collective behaviour can be observed within human groups. A research collaboration beetween TSF team of LAAS-CNRS, the LPT1, the CRCA/CBI2 and the TSE-R3 has focused on segregation, and on the information necessary to trigger it. This study, published on The Royal Society revue, could shed light on the polarisation of opinion on social media.

Contrary to preconceived notions, crowds are hardly unpredictable. Researchers are perfectly capable of quantifying and modelling their movements. A few simple rules of individual behaviour – do not walk into walls, do not bump into fellow humans – are enough to produce a computer simulation of thousands of people walking within a space. However, when the individuals in this crowd are given an objective and some information, surprising and sometimes violent collective phenomena can suddenly happen, such as the wave in stadiums, the storming of the Capitol in Washington (US), and deadly stampedes.

For several years, the duo formed by Clément Sire, a physicist at the LPT1 and Guy Théraulaz, an ethologist at the Research Center on Animal Cognition2 both in Toulouse (southwestern France), have examined the phenomena at play when a large number of individuals, whether humans or animals, gather together and interact with one another. From schools of sardines to clouds of starlings or a crowd in the Underground, they try to work out the interactions and rules of behaviour that can explain the occurrence of self-organisation observed in these collectives. « We use the tools of statistical physics to model this demeanour. Once we have understood individual interactions, we can develop models and understand certain manifestations of collective intelligence observed in animal and human societies » explains Théraulaz.

Understanding the link between information and organisation

The researchers are especially interested in communication within human and animal groups. « We try to quantitatively measure social interactions between individuals in order to understand the shared behaviour they give rise to » adds Sire. They are trying in particular to identify what information alters the movements of these systems. In other words, what instructions or basic data must individuals exchange in order for these particular forms of organisation to emerge within these collectives.

In collaboration with Dependable Computing and Fault Tolerance - TSF team of LAAS-CNRS and Toulouse School of Economics-Research3, the scientists devised an original experiment that sheds lights on how information can lead groups of people to split into two. This enabled them to explore segregation, a behaviour that brings to mind physical phenomena such as the separation of oil and vinegar in salad dressing – and social ones such as segregation in cities or the polarisation of opinion on social media.

[...] read the full article on the CNRS News website.

1 Laboratoire de physique théorique (LPT - CNRS, Université Toulouse III - Paul Sabatier)
2 Research Center on Animal Cognition (CRCA/CBI - CNRS, Université Toulouse III - Paul Sabatier)
3 Toulouse School of Economics-Research (TSE-R - CNRS, Université Toulouse 1 Capitole, INRAe)