Many observers have hailed the recent surge of open-access titles launched by commercial publishers as evidence that science is firmly on the road to a fully open-access future.
But it's a different story in the humanities and social sciences, and the jury is still out on the wisdom of SAGE, the US social science publisher, in launching the first major open-access title outside the sciences.
Even Jayne Marks, vice-president and editorial director of the publisher's library information group, described SAGE Open, which will span the humanities and social sciences, as "very much a test model".
Recent figures suggest that 14 per cent of open-access journal publishers are in the humanities, but they account for just 4 per cent of all open-access articles.
Niche open-access journals often operate out of university departments and rely on little more than what Michael Jubb, director of the UK's Research Information Network, called "the goodwill and hard work of the people who run them".
One example is Stanford University's Occasion, which spans the humanities and social sciences. According to its founding editor, David Palumbo-Liu, it was set up because of frustration with traditional publishers' lack of interest in papers from an interdisciplinary conference.
He said he felt positive about the "opportunity to disseminate texts at such relatively low cost, with the chance also to get feedback, revise and expand easily". But he admitted that journals such as his were "charting new waters" - and "the going is a bit rough".
Occasion does not levy article-processing charges. That policy, which is common outside the sciences, highlights the central problem in getting the open-access movement off the ground in the humanities and social sciences: the lack of money to pay the processing charges or submission fees that would make open-access publishing self-sustaining.
According to Dr Jubb, most humanities research is in essence funded out of the salaries paid to academics. This means there is "no opportunity for spare cash at the end of a project grant out of which to pay publication fees".
And those researchers who do have grants often receive them from multiple agencies, said Mary Waltham, an independent publishing consultant. "Grants interweave and overlap, so attributing a piece of research to a funding agency and using research money from that source plainly has complexities."
Ms Waltham carried out a study in 2009 that concluded that a move to author-pays open-access publishing in the humanities and social sciences was financially unsustainable, at least for flagship titles.
For its first year, Sage Open will charge just $195 (£122) to process an article, but Ms Marks admitted that the figure would not cover SAGE's costs and would have to rise to $695 in the second year.
Also going some way to explain the lack of open-access fervour is the fact that the cost to universities of humanities journals - many of which publish only three or four editions a year - are minuscule when compared with journals in the sciences, technology, engineering and mathematics. Thus, said Chris Pressler, director of university libraries at the University of London, librarians have not pressed as hard and as vociferously for a less costly alternative model as they have with the publishers of STEM journals.
Why the reluctance?
But Colin Steele, an emeritus Fellow at the Australian National University, confessed surprise at the lack of ideological enthusiasm for open access among the humanities and social sciences community.
"One would think it would be a natural outlet for these disciplines, particularly as a significant amount of their content would be instantly accessible to a wider public," he said, adding that this could also help demonstrate impact to funders.
The status of the monograph as the gold standard of scholarship outside the sciences may also play a part, he continued.
But Dr Jubb noted that the rise of research assessment has led non- science researchers to publish more articles to demonstrate their productivity. Meanwhile, the soaring costs of STEM journal subscriptions means libraries have less money to spend on monographs - leading to smaller print runs and rising unit costs - "a classic downward spiral".
Might open access offer a route to sustainability for monograph publishers? Dr Steele thinks there is a viable model, involving university presses that have "returned to their origins in distributing the knowledge of their own university".
He cited the Australian National University's E Press, set up in 2003 and since copied by Monash and Adelaide universities. For "relatively small" costs, it has led to a huge increase in the distribution of ANU's scholarship. But he admitted that such an approach was "not as easy for commercial operators with traditional business plans".
Dr Jubb echoed that sentiment. "It is hard enough for journals in the sciences. For monographs in the humanities, making open access sustainable will be much harder."