Ya,i can relate to this. I think there's probably more to it than just balancing a rooms mood. Generally, if I arrive and there's a negative or pessimistic vibe I'll pick up on it. Usually I care why people are miserable and often my friends look to me to help or ask for an input to shed light on a situation or feeling from another point of view. So I'll be able to give a perceived optimistic solution in the eyes of people who cant look at a situation from different view points, unable to see any positives in their dilemma. I'll also take time to listen to them and sometimes offer a solution or advice which helps them feel better, and the mood lifts.
Also, I've experienced the 'sobering' affect in group situations. I've noticed I can tune in to one part of a discussion and dwell on it, I'll focus on a point and ponder on it in depth. When someone notices I'm quiet they'll usually assume somethings wrong. Usually, if I explain what I'm thinking about the point is more detailed but still relevant to the conversation leading people to discuss a passing topic in more detail, which, in a fast-paced conversation can end up slowing down the overall frenzied natter going on in a social circumstance, often leading me too feel I've had a 'sobering' effect on the people surrounding me...oops!
