Jan-Willem van Prooijen is a behavioural scientist. He is an associate professor of social psychology at Vrije Universiteit Amsterdam, a senior researcher at the Netherlands Institute for the Study of Crime and Law Enforcement (NSCR), and Endowed Professor of Radicalization, Extremism, and Conspiracy Thinking at Maastricht University. He has been studying conspiracy theories since 2008 and has published widely on the topic. His books include The Psychology of Conspiracy Theories (2018), The Moral Punishment Instinct (2018) and, as editor, The Psychology of Political Polarization (2021).