He works as a scientific staff member at the University of Amsterdam. For many years he belonged to the top of Dutch amateur chess players. Dr. Eric-Jan Wagenmakers is a mathematical psychologist. He works as a scientific staff member at the University of Amsterdam. Together with Prof. Dr. Han van der Maas he developed the Amsterdam Chess Test (ACT), a test that measures chess playing proficiency. For many years he belonged to the top of Dutch amateur chess players.