Thomas Eger, Marc Scheufen, and Daniel Meierrieks have self-archived "The Determinants of Open Access Publishing: Survey Evidence from Germany" in SSRN.
Here's an excerpt:
We discuss the results of a survey conducted in fall 2012 and covering 2,151 researchers in Germany. We show that there are significant differences between the scientific disciplines with respect to researcher's awareness of and experience with both open access (OA) journals and self-archiving. Our results reveal that the relevance of OA within a discipline may explain why researchers from particular disciplines do (not) publish OA. Besides, several aspects like copyright law, age, profession or the inherent reward system of a discipline play a role. As a consequence, the paper emphasizes that a "one-size-fits-all" approach as promoted by most recent policy approaches is little promising for providing an effective framework for shaping the future of scholarly publishing.