Thesis about Group Decision Making; PhD degree for Hanneke Kooij-de Bode

On November 2, Hanneke Kooij-de Bode defended her PhD thesis entitled “Distributed Information and Group Decision Making: Effects of Diversity and Affect”. Her promoter is Prof.dr. D.L. van Knippenberg, Professor of Organisational Behaviour, RSM Erasmus University.

Hanneke Kooij-de Bode (1964) graduated in 2002 cum laude in the field of Work and Organizational Psychology at the University of Amsterdam. In the same year she started her PhD project at the RSM Erasmus University. The research reported in this dissertation was conducted between 2002 and 2007. Hanneke currently works as a researcher/advisor at TNO (Netherlands Organization for Applied Scientific Research).

Abstract
Organizations tend to rely on small groups rather than individuals when important decision have to be made, based on the assumption that groups possess a broader range of informational resources and more diversity of insights than individuals. However, research on group decision-making shows that groups often fail to use effectively group members’ unique information. Central in this dissertation is the relationship between distributed information, the way groups’ process information, and the quality of the group decision. In three experiments, the influence of demographic diversity, dispositional negative affect, and mood on groups’ information elaboration process and groups’ decision quality is studied.

Results indicate the following: Groups with distributed information and diverse demographic backgrounds elaborate information more and reach better decisions with a focus on information exchange and integration than without such a focus. Higher dispositional negative affect within a group with distributed information stimulates information elaboration and group decision quality. A negative mood within a group with distributed information only affects information elaboration within a group and groups’ decision quality positively if group members are lower in dispositional distress. In all three single experiments, information elaboration within a group mediates groups’ decision quality.

It is concluded that diversity and affect – as disposition as well as mood – are important issues to include in group research and implications for research in organizational behaviour are discussed.

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