Universiteit Leiden

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Welmer Molenmaker

Assistant Professor

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

Welmer Molenmaker started studying psychology at the University of Amsterdam in 2005. Following the completion of his bachelor’s degree in 2009, he obtained his research master’s degree in 2011. The general emphasis during his research master was on social psychology, cognitive neuroscience, research methodology, and sport psychology. In September 2011, Welmer started a PhD project – which focused on the (un)willingness to reward cooperation and punish non-cooperation – at Leiden University. Currently, he works as an Assistant Professor at the Social and Organizational Psychology unit of 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.

Grants and Awards

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

Relevant links

Assistant Professor

  • Faculteit der Sociale Wetenschappen
  • Instituut Psychologie
  • Sociale en Organisatiepsychologie

Work address

Pieter de la Court Building
Wassenaarseweg 52
2333 AK Leiden
Room number 2A35



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