In this paper, we present a system that acts as an automatic facilitator by supporting the flow of communication in a group conversation activity. The system monitors the group members' non-verbal behavior and promotes balanced participation, giving targeted directives to the participants through peripheral displays. We describe an initial study to compare two ways of influencing participants' social dynamics: overt directives, explicit recommendations of social actions displayed in the form of text; or subtle directives, where the same recommendations are provided in an implicit manner. Our study indicates that, when the participants understand how the implicit messages work, the subtle facilitation is regarded as more useful than the overt one and it is considered to more positively influence the group behavior.