Universiteit Leiden

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Welmer Molenmaker

Assistant Professor

Dr. W.E. Molenmaker
+31 71 527 1440

Short CV

Welmer Molenmaker obtained his research master's degree in psychology at the University of Amsterdam in 2011. From 2011 to 2015, he worked as PhD candidate at Leiden University. His PhD project focused on the (un)willingness to reward cooperation and punish non-cooperation. Currently, he works as Assistant Professor of Social and Organizational Psychology at Leiden University and is a member of the Leiden Institute for Brain and Cognition (LIBC).


The main research interest of Welmer Molenmaker is social decision making. Specifically, he focusses on human cooperation and the (un)willingness to reward cooperation and punish non-cooperation.

Why do people cooperate?

The greatest challenge for all societies, regardless of how advanced they are, is to ensure and protect the collective welfare. This challenge arises from the fact that the interests of the collective do not necessarily coincide with the personal interests of the people belonging to that collective. Thus, on many occasions, people face a dilemma between furthering the collective interests or furthering their personal interests. Despite this 'dilemma', empirical research has consistently shown that people frequently cooperate with each other, even if they do not know each other. Welmer’s research is aimed at answering the question why people cooperate with others.

Why are people (un)willing to reward cooperation and punish non-cooperation?

One of the most straightforward ways to protect the collective welfare is to use sanctions. Numerous experiments have consistently shown that positive sanctions (rewards) for cooperation and negative sanctions (punishments) for non-cooperation can effectively enhance cooperation. Although this is an important insight, a critical question remains: Are people actually willing to sanction? This question is of critical importance, if only for the obvious reason that someone should first be willing to administer rewards and punishments before they can show their effects. Welmer’s research is aimed at answering the question why people are (un)willing to reward cooperation and punish non-cooperation.


  • Postgraduate travel grant by the European Association of Social Psychology (2014)
  • Leiden University fund grant (2014)


  • Best Student Paper Award at the 16th International Conference on Social Dilemmas, The Chinese University of Hong Kong (2016)
  • Scholar Award by the Dispute Resolution Research Center at Kellogg School of Management, Northwestern University (2014)

Relevant links

Assistant Professor

  • Faculteit der Sociale Wetenschappen
  • Instituut Psychologie
  • Soc., Econom. en Organisat Psych.

Work address

Pieter de la Court
Wassenaarseweg 52
2333 AK Leiden
Room number 2A32



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