Group process: the black box of studies on problem-based learning.

A considerable number of medical schools worldwide have implemented, at least in part, a problem-based learning (PBL) approach in their curricula. Research to date has largely neglected the issue of the actual activities and learning processes that mediate and moderate the relationship between these programs and their cognitive outcomes. In this essay the authors discuss the few studies that have empirically investigated what students actually do in PBL tutorials, which arguably is the pivotal mediating process. These studies demonstrate that it is possible to observe, identify, and describe group activities (such as brainstorming and the joint identification of learning issues) that promote interactionally shared and achieved cognition. However, such studies have been confined to case studies in which isolated fragments of tutorials have been analyzed and described. Future studies need to provide a broader description and analysis of actually performed cognitive activities in all relevant phases of the entire PBL process.