Alexander J. Stewart is a professor at the School of Mathematics and Statistics at the University of St Andrews and (from Jan 2025) an associate professor at the Luddy School of Informatics, Computing and Engineering at IU Bloomington.

In his research, Alex uses mathematical and computational models to study learning and decision-making in humans. His current focus is on combining such models with data and experiments to understand better how individual-level decision-making scales up to produce population-level phenomena such as polarization, echo-chambers, or widespread misinformation and extremism. He is especially interested in how these phenomena play out in online environments, in which information flow is shaped by the interaction between individual decisions and platform rules and algorithms.

Earlier in his career, Alex received an MSci in Physics from Imperial College London, then an MRes and PhD from University College London (UCL). This was followed by a postdoc at the University of Pennsylvania before returning to UCL as a Royal Society University Research Fellow.