Regardless of how social relationships are modeled in online software (be it community, group, 2-way/symmetrical, or 1-way asymmetrical models) more attention seems to result in increased contribution -to a point.
To illustrate, when an average Twitter user gets to 1,000 followers, they move from 3 daily updates to 6. That number rises to 10 average daily updates with 1,750 followers (source). Conversely, less attention often means less production. In a study of over 500,000 users on YouTube, research showed that a decreasing number of video views resulted in a lack of contribution. In this case, to the point of making contributors stop uploading any additional videos.
While an increase in the number of explicit social relationships can initially drive substantial increases in contribution, the rate of increase begins to level off and eventually plateau. Looking again at Twitter contribution data, we can see that while the number of posts increases as followers increase, it eventually saturates. So attention drives contribution but only to a point.
For more insights from online social relationships, check out my complete Impact of Social Models presentation.