Mindguard
A mindguard, according to groupthink theory, is a member of a group who serves as an informational filter, providing limited information to the group and, consciously or subconsciously, utilizing a variety of strategies to control dissent and to direct the decision-making process toward a specific, limited range of possibilities. The presence of mindguards within a group is one of eight main "symptoms" of groupthink identified by its original theorist, Irving Janis. Multiple mindguards are frequently present in groupthink situations.