Two experimental studies test the effect of group mirrors upon quantitative and qualitative aspects of participation in collaborative problem solving. Mirroring tools consist of a graphical representation of the group's actions which is dynamically updated and displayed to the collaborators. In addition, metacognitive tools display a standard for desirable behavior. Results show that a mirroring tool did not substantively affect the behavior of subjects while a metacognitive tool led to increased participation in dialogue, including more frequent and precise planning.