To test this theory, James A. Evans, an assistant professor of sociology at the University of Chicago, and Jacob Reimer, a student of neurobiology also at the University of Chicago, analyzed millions of articles available online, including those from open source publications and those that required payment to access.

The results were surprising. On average, when a given publication was made available online after being in print for a year, being published in an open source format increased the use of that article by about 8 percent. When articles are made available online in a commercial format a year after publication, however, usage increases by about 12 percent.

“Across the scientific community,” Evans said in an interview, “it turns out that open access does have a positive impact on the attention that’s given to the journal articles, but it’s a small impact.”

Yet Evans and Reimer’s research also points to one very positive impact of the open source movement that is sometimes overlooked in the debate about scholarly publications. Researchers in the developing world, where research funding and libraries are not as robust as they are in wealthier countries, were far more likely to read and cite open source articles.

The University of Chicago team concludes that outside the developed world, the open source movement “widens the global circle of those who can participate in science and benefit from it.”

So while some scientists and scholars may chose to pay for scientific publications even when free publications are available, their colleagues in other parts of the world may find that going with open source works is the only choice they have.