High Quality Content by WIKIPEDIA articles! Diederik Alexander Stapel (born 19 October 1966 in Oegstgeest) is a former professor of social psychology at Tilburg University and before that at the University of Groningen in the Netherlands. In 2011 Tilburg University suspended Stapel, pending further investigation, for fabricating and manipulating data for his research publications. This scientific misconduct lasted for years and affected at least 55 publications.