In a previous blog I describe how being the first person to speak (in a group) results in framing the ensuing discussion (Start the discussion, frame the discussion).
In this blog I describe how simply talking a lot results in influencing the group.
The following comes from The Wisdom of Crowds by James Suroweicki:
Talkativeness has a major impact on the kinds of decisions small groups reach. If you talk a lot in a group, people will think of you as influential almost by default. Further, talkativeness feeds on itself: the more you talk, the more you are talked to by others in the group, which causes you to talk more, and so forth. So talkative people tend to become increasingly important over the course of a discussion.
Want to influence a group? Be the first person to speak, and be talkative.