Thanks to @davefauth I came across an interesting blog post by Naumi Haque on the diminishing returns of collaboration. The basis of his thesis is that as the number of explicit collaborators in a project increases past a certain point, the overall utility decreases due in part to costs associated with maintaining the collaboration. This reminds me of the notion of group coherence that Morten Hertzum wrote about in his paper on Collaborative Information Seeking. He focused on the need for teams to devote resources to ground the collaboration to prevent loss of coherence (and thus shared goals and values).
It is interesting to contrast these theories with our assumptions of more focused collaboration that underlie collaborative search. When Hertzum and Haque argue that effort is required to maintain collaborative teams, we assume that they mean this in the long run rather than during some focused activity such as an information seeking session, even one that spans a few days. But it is interesting to note that when talking about collaboration, we’ve been focusing on understanding and supporting the needs of small collaborating groups of 2-5 people. While it is possible to imagine larger groups engaging in explicit collaboration, organizational structures would probably need to exist to compensate for the size of the group.
These constraints do not apply to other kinds of social search (e.g., recommendation systems) because in those cases people do not actually work together toward a shared information need and thus do not need to manage social aspects of the relationship. It is ironic that in this sense, collaborative search is more truly social than other kinds of social search.