What we are

Individual decisions can have a large impact on society as a whole. This is obvious for political decisions, but still true for small, daily decisions made by common citizens. Individuals decide how to vote, whether or not to stay at home when they feel sick, to drive or to take the bus. In isolation, these individual decisions have a negligible social outcome, but collectively they determine the results of an election and the start of an epidemic. For many years, studying these processes was limited to observing the outcomes or to analysing small samples. New data sources and data analysis tools have made it possible to start studying the behaviour of large numbers of individuals, enabling the emergence of large-scale quantitative social research.

At the Social Physics and Complexity (SPAC) lab we take a data-driven complex systems approach to better understand individual behavior and its societal consequences.

In the past, we have worked on three types of problems, strongly dependent on both the behaviours of individuals (in what we call bottom-up collective processes), and of decision-makers (the top-down decisions). More recently we focused on two main areas:

Disease dynamics, of both infectious and non-infectious diseases. We strive to help policy makers in disease control (including during the pandemic) and we try to answer questions such as:

  • Can we use online data to improve nowcasting and forecasting of several diseases?
  • How can we reduce antibiotic over-prescription?
  • How is climate change impacting disease dynamics?

Behavior, both online and offline. This is much more fundamental and it comes from the realization that the Digital Era is offering us a giant mirror, a macroscope, that will allow us to understand human behaviour at a completely new scale. By using both social networks and the spread of fake news as case studies, we are trying to identify underlying principles, both mathematical and behavioural, that can be generalized to different contexts. We ask:

  • Can we use online behaviour to learn about cognitive biases?
  • Can we identify small behavioural sub-populations and predict their larger impact(s)?
  • Can we use this “macroscope” in an ethical manner?

We have been awarded an ERC grant to study such biases in decision-making, using fake news sharing as a case-study.

In parallel, and recognizing that these tools might also have a very negative impact on society, we try to raise public awareness of these risks of the Digital Era and involve citizens in the definition of appropriate ethical guidelines and legislation.


Our ultimate goals are to learn about human behaviour and to engage scientists and non-scientists in the creation of a more knowledgeable and critical society.