[ Apologies that I'm late to the party. I attempted to send this some time ago but from the "wrong" email address and didn't notice when it bounced. ]
<quote who="Chitu Okoli" date="Thu, Apr 26, 2012 at 04:02:39PM -0400">
In this case, I actually started this project with the hunch that barnstars would lead to a slight decline in editing behavior; my rationale was that rewards would act as social markers that editors' past work was sufficient to earn social recognition and hence receiving such a reward would signal that the editor had "done enough" for the time being. In addition to there being substantial support for this idea in the economics literature, this intuition stemmed from hearing about an (unpublished) observational study of barnstars by Gueorgi Kossinets (formerly at Cornell, now at Google) that suggested editors receive barnstars at the peak of their editing activity.
Aaron Shaw, Yochai Benkler and I have a working paper on barnstars as well which consider them observationally and find support for this finding. This is complicated by the fact that barnstars are endogenous to editing behavior (outside of Restivo's study); people don't get barnstars randomly. :) It makes sense that folks will be congratulated for doing work at the point at which they are, on average, doing the most and should be surprised if this is not the case.
In part because of this fact, my own work hasn't focused on effect of the awards but on how we can use them to get at sub-population differences among recipients.
If folks are are curious, Aaron and I will be presenting some of this work at Wikiamania as part of this session:
https://wikimania2012.wikimedia.org/wiki/Submissions/Can_Social_Awards_Creat...
If he can make it, Michael Restivo might present the experiment as part of that session as well.
Regards, Mako