Empirical evidence on how cognitive factors impact the effectiveness of model-supported group decision making is lacking. This study reports on an experiment on the effects of need for closure, defined as a desire for definite knowledge on some issue and the eschewal of ambiguity. The study was conducted with over 40 postgraduate student groups. A quantitative analysis shows that compared to groups low in need for closure, groups high in need for closure experienced less conflict when using Value-Focused Thinking to make a budget allocation decision. Furthermore, low need for closure groups used the model to surface conflict and engaged in open discussions to come to an agreement. By contrast, high need for closure groups suppressed conflict and used the model to put boundaries on the discussion. Interestingly, both groups achieve similar levels of consensus, and high need for closure groups are more satisfied than low need for closure groups. A qualitative analysis of a subset of groups reveals that in high need for closure groups only a few participants control the model building process, and final decisions are not based on the model but on simpler tools. The findings highlight the need to account for the effects of cognitive factors when designing and deploying model-based support for practical interventions. 
Different paths to consensus? The impact of need for closure on model-supported group conflict management