  Understanding social interaction within groups is key to analyzing online
communities. Most current work focuses on structural properties: who talks to
whom, and how such interactions form larger network structures. The
interactions themselves, however, generally take place in the form of natural
language --- either spoken or written --- and one could reasonably suppose that
signals manifested in language might also provide information about roles,
status, and other aspects of the group's dynamics. To date, however, finding
such domain-independent language-based signals has been a challenge.
  Here, we show that in group discussions power differentials between
participants are subtly revealed by how much one individual immediately echoes
the linguistic style of the person they are responding to. Starting from this
observation, we propose an analysis framework based on linguistic coordination
that can be used to shed light on power relationships and that works
consistently across multiple types of power --- including a more "static" form
of power based on status differences, and a more "situational" form of power in
which one individual experiences a type of dependence on another. Using this
framework, we study how conversational behavior can reveal power relationships
in two very different settings: discussions among Wikipedians and arguments
before the U.S. Supreme Court.
