Discipline-specific open access publishing practices and barriers to change: an evidence-based review

Prevalence and patterns of open access publishing practices: Meta-synthesis of bibliometric studies

The objective of our review is to identify and synthesize large-scale bibliometric studies on the prevalence and patterns of OA publishing across academic disciplines. Such studies usually analyse similar samples of academic publications, including data from Web of Science (WoS), Google Scholar (GS) and Scopus, but employ different methods for identifying disciplinary publishing practices within these databases. This relates to definitions of OA, included OA routes, covered publication years and employed search strategies for OA full texts. For this reason, we conducted a meta-synthesis. The aim of a meta-synthesis is to qualitatively integrate, compare and analyse methodologically heterogeneous studies, thereby allowing the emergence of interpretive themes¹¹. In this study, we synthesised the results from bibliometric studies to identify patterns of OA publishing practices across academic disciplines. The search was pre-planned and comprehensively, as it aimed to seek all available studies. No date limits were employed. The searches were conducted in August to October 2018. Bibliometric studies were searched in a systematic way. This involved, first, the querying of the online data bases ScienceOpen, Scopus, WoS and GS. The search was conducted using the following search string: “Discipline” AND “Publish*” AND “Open access” OR “OA”. The selection of the search terms was based on the topic literature on scholarly communication. Second, reference lists and bibliographies of all included studies were evaluated manually for additional publications. Having identified key experts within the field, their GS profiles were also searched for material. In an initial screening stage, two independent reviewers screened titles and abstracts of studies and decided on whether to include respective studies in the review. Studies were excluded that did not meet our selection criteria, as outlined in Table 1. This procedure resulted in a total of 11 studies. In a second screening stage, we assessed the full text of the included studies. In order to gain the data of interest to our review, we analysed the “Results” sections of primary studies and extracted data on reported proportions of publications that were OA, including both the overall OA proportions and the relative uptake on OA routes.

Mechanisms and factors shaping open access publishing practices: Narrative review of sociotechnological forces

Our goal in this section is to explain the patterns of OA publishing practices that we observed in the previous section. To do this, we performed a narrative review of the mechanisms and factors that shape OA publishing practices in different academic disciplines. Thereby, we aim to identify discipline-specific barriers and potentials for OA. We recruited an interdisciplinary team of researchers covering the broad academic disciplines natural and technical sciences, medicine and health-related sciences, social sciences and law, arts and the humanities. Each co-author of our team examined evidence on factors that shape OA publishing practices within their own areas of research training. In doing so, we did not perform a systematic review of the literature. Instead, we developed an analytical framework of socio-cultural and technical factors that generally shape publishing practices. Each co-author used this framework as a tool for identifying the socio-technical mechanisms and factors that shape OA publishing practices within their own discipline. The evidence included in this review was identified and selected through queries of online databases, including ScienceOpen, Scopus, WoS and GS. Reference lists and bibliographies of relevant studies were evaluated manually for additional evidence. Having identified key experts within the field, their GS profiles were also searched for material. Each co-author contributed original content on OA in their discipline and participated in the reviewing and editing process.

Prevalence and patterns of open access publishing practices: Meta-synthesis of bibliometric studies

The characteristics of the studies included in our review are presented in Table 2. In general, studies were concerned with the questions of (1) how much of the scholarly literature in a academic discipline is openly accessible, and (2) via which OA route scholarly outputs are made openly accessible. Earlier studies analysed random samples of academic publications from bibliometric databases, such as Scopus or WoS, whereas more recent studies examined these databases in full. Making use of automated web search strategies, studies assessed whether openly accessible versions of sampled scholarly publications could be found on the web, for example through GS. On this basis, studies determined OA levels and the relative uptake on different OA routes across disciplines. Earlier studies distinguished between Green OA, which refers to articles published in subscription-based journals, but for which either the accepted or the published version can be retrieved from an open repository, and Gold OA, which describes articles published in OA journals, that is, journals in which all articles are openly accessible. More recent studies also include Hybrid OA, which refers to articles free under an open license in a subscription journal, and Bronze OA, which describes articles free to read on the publisher page without an open license^{12 1}.

Table 3 shows the main findings of the studies included in our meta-synthesis. Looking at the overall prevalence of OA for all disciplines, we see that the system of academic publishing has experienced a shift from “closed” access to OA: OA levels have increased steadily across all disciplines, from 20.4% of all scholarly outputs reported as OA in 2008¹⁵, to 23% in 2010⁹ and more than half of all scholarly outputs being OA in publication years later than 2010: 53.7% for publication years 2011 until 2013¹⁶, 54.6% on average in years 2009 and 2014¹⁷, 66& for publication years between 2009 and 2017¹⁸ and 55% in 2014¹⁹. Two studies determined the prevalence of OA to be less than 50% for publication years later than 2010: Piwowar et al. determined that on average 36.1% of the scholarly literature was made OA in the time period between 2009 and 2015 and Bosman and Kramer found this share to be 29.4% for 2016^12,20. Looking at how different disciplines implemented OA over time, we can distinguish between three phases. Dated between the early 1990s and the mid to late 2000s, the first phase can be characterised as a phase of formation: A few fields related to the natural and technical sciences took on a pioneering role in implementing OA, amongst these particularly mathematics (reported OA levels of 25.6% and 42% in 2008 and 2010, respectively^1,9) and physics and and space-related research fields (OA levels of 32.9% for earth sciences and 23.5% for physics & astronomy in 2008, and 37% for earth & space and 27% for physics in 2010^1,9). An exception to this are the fields engineering and chemistry, which feature OA prevalence rates that consistently are lower than all natural and technical sciences and lower than most other disciplines, including the social sciences and the humanities^1,9. The social sciences were also fast in embracing OA, featuring OA prevalence levels only slightly below those reported for the natural and technical sciences (16% OA in sociology in the time from 1992 to 2003, followed by economics with 13.5% OA and business with 9% OA²¹; 23.5% OA and 37% OA observed in the social sciences for publication years 2008 and 2010, respectively^1,9). Medicine and health-related research fields were substantially slower in implementing OA than most natural and social sciences (OA levels of 6.2% in medicine between 1992 and 2003²¹; 21.7% for medicine and 15.2% for other areas related to medicine in 2008¹; 17%, 14% and 12% OA reported for health, clinical medicine and biomedical research in 2010, respectively⁹). As such, medicine and health-related fields implemented OA to an even smaller degree than the humanities have in the early years of OA (19% OA reported for humanities in 2010⁹). The second phase of OA is dated between the mid 2000s and the mid 2010s and can be characterized as a period of transformation. In medicine and health-related research fields, OA uptake increased substantially, causing OA levels in these fields to equal or surpass OA prevalence in the social sciences and humanities (26% OA determined for medicine for publication years until 2013, while 24% OA showed for arts and humanities²²; 59.7% OA in health sciences between 2004 and 2014, while 60.8% of publications in social sciences were OA¹⁶). For the early period of this phase, OA levels in the natural and technical sciences remained well above those observed in other disciplines (Observed OA levels were 50% in computer sciences, 35% in both geo-sciences and physics, 29% in environmental sciences and 27% in mathematics in publication years until 2013²²; 60% OA in physical sciences in the time from 2004 to 2014¹⁶). Because of higher OA growth rates in medicine and health towards the end of this phase, these fields soon overtook the natural and technical sciences in embracing the idea of OA. Particularly biomedical research took on a leading role in embracing OA (70.6% OA in biomedical research, 67.6% OA in mathematics & statistics, 66.2% for biology, 59.4% for physics & astronomy and 58.8% for earth and environmental sciences, closely followed by public health & health services and clinical medicine with OA levels of 57.2% and 56,3%, respectively, in the period from 2011 to 2013¹⁰). During this period, the gap between the natural and technical sciences and medicine on the one side and the social sciences and humanities on the other side widened. The humanities in particular published research outputs to lesser degrees OA than other disciplines (35.0% OA in arts, humanities & social sciences, 34.7% in philosophy & theology, 34.4% in historical studies for publication years 2011 to 2013)¹⁰. The third phase of OA can be dated after the early 2010s and is a phase of stabilisation, in which differences in the OA publishing patterns across disciplines have become established. Studies consistently show that medical and health-related research fields are taking the leading roles in embracing OA, featuring OA uptake levels that are well above those reported for other disciplines (Reported OA levels are 60% in medical and life sciences on average for 2009 and 2014¹⁷; 59% for health sciences in 2014¹⁹; 58.5%, 47.8% and 41.8% for biomedical research, clinical medicine and health in publication years from 2009 to 2015, respectively¹²; 41.7% for life sciences and biomedicine in 2016²⁰ and 85%, 79% and 73% for biomedical research, clinical health and health in publication years from 2009 to 2017, respectively¹⁸). The medical sciences are closely followed by disciplines from the natural and technical sciences (50% OA for natural sciences on average in 2009 and 2014¹⁷; 55% OA for natural sciences in 2014¹⁹; 52.7% OA for mathematics, 40.4% OA in earth and space, 32.7% OA in biology and 31.6% OA in physics between 2009 and 2015¹²; 14.8% for physical sciences / technology in 2016;²⁰; 57% OA for mathematics, 56% OA for earth and space, % 56% OA for physics and 51% OA for biology in publication years from 2009 to 2017¹⁸). OA uptake in the social sciences is close behind the natural sciences (Reported OA levels are 49.9% for social and behavioural sciences in 2009 to 2014¹⁷; 55% for economic and social sciences in 2014¹⁹; 25.1% in social sciences between 2009 and 2015¹²; 17.3% in social sciences for 2016²⁰; 39% for social sciences between 2009 and 2017¹⁸). Law, arts and humanities show the lowest OA uptake across all disciplines (OA prevalence rates determined to be 32.3% for law, arts and humanities between 2009 and 2014¹⁷; 24% for arts and humanities in 2014¹⁹; 13.9% for arts and humanities in 2016²⁰).

Looking at the relative uptake of OA routes for all disciplines, we observe that most OA is published via the Green route, that is, published as journal articles for which the accepted or the published version can be retrieved from an open repository. Gold OA journals are also of importance for scholarly publishing, even though the relative uptake on Gold OA remains well below Green OA for most publication years (Relative uptake levels were 11.9% Green OA and 8.5% Gold OA in 2008, respectively,¹, 21% Green OA and 2% Gold OA in publication years from 2005 to 2010⁹, 5.9% Green OA and 12.1% Gold OA between 2011 and 2013¹⁰, 10.8% Green OA and 7.3% Gold OA on average in publication years 2009 and 2014¹⁷, 8.8% Green OA and 49.4% Gold OA in publication years between 2004 and 2014¹⁶, 31% Green OA and 23% Gold OA in 2014¹⁹ and 11.5% Green OA and 7.4% Gold OA in publication years between 2009 and 2015¹²). Studies that also assessed the relative uptake on Hybrid OA and Bronze OA have revealed, that, first, Hybrid OA generally is of little importance for scholarly publishing, with 1% or less of all scholarly outputs being published as articles free under an open license in subscription journals. Second, the importance of Bronze OA is comparable to that of Gold OA. Relative uptake on Bronze OA was determined to be an average 13.2% for publication years 2009 and 2014 and 12.9% for publication years from 2009 to 2015^12,17. Looking at the relative uptake on OA routes by discipline, we observe that there is little consistency in reported uptake levels across the studies included in our review, which likely is due to methodological differences in how studies determined how much of the scholarly literature in a specific discipline is published through different OA routes. Nevertheless, we are able to determine the relative importance of the different OA routes for each discipline: For the medical sciences, we observe that publication in pure OA journals (Gold OA) plays a more important role for making research findings openly accessible than both the archiving of articles in repositories following publication in subscription journals (Green OA) and the publication of articles free under an open license in subscription journals (Hybrid OA). Two more recent studies have revealed that the publication of articles free to read on the publisher page without open license (Bronze OA) also is of substantial relevance for OA in the medical sciences, featuring similar prevalence levels as Gold OA. For the natural and technical sciences, we see that there are substantial differences in the OA publishing patterns between different fields: scholars in physics, mathematics, astronomy and biology make large shares of their research outputs openly accessible through the Green route of OA, followed by Bronze OA, Gold OA, and, with some distance, Hybrid OA. In contrast, for scholars in chemistry and biology, Gold OA journals are of greater importance than any other OA route. For scholars in the social sciences, Green OA is of greater importance for OA publishing than Gold OA, Bronze OA and Hybrid OA. In the humanities and law, scholars make research outputs openly accessible predominantly through publication of articles in Hybrid OA journals, followed by Green OA, Bronze OA and Gold OA.

Analytical framework: Social shaping of technology

Previous studies have analysed discipline-specific publishing practices from a range of perspectives. In general, these perspectives originate from science and technology studies (STS), which look at how society, politics and culture shape research and technological innovation, and vice versa. Depending on their understanding of the direction of this relationship, these perspectives can be located on a scale that ranges from technological determinism at the one extreme to social constructionism of technology (SCOT) at the other extreme²³. These perspectives emphasize particular sets of criteria as relevant for analysing publishing practices while other sets of criteria are considered irrelevant or ignored⁵. Technological determinism suggests that technology is the driving force behind social and cultural change²⁴. Studies adopting this perspective accordingly focus on the infrastructures and technical aspects of scholarly communication channels in explaining how OA is implemented across disciplines. Social and cultural factors are believed to be of less or no relevance in explaining the emergence of OA⁵. SCOT perspectives view technology as a social phenomenon constructed by the society producing and using it. In order to analyse OA publishing patterns, one would have to first understand the social relations within which respective technologies are used²⁵. Both positions have been shown to suffer from limitations in explaining scholarly publishing practices². The so-called “social shaping of technology” (SST) perspective that takes an intermediate standing between these extremes proves to be more useful for analysing OA publishing practices. SST is a theoretical stance that conceives the relationship between technology and society as one of mutual shaping²⁶. Instead of evolving according to an inner technical logic or a single social determinant, technology is believed to be a social product patterned by the conditions of its creation and use²⁷. Central to technical change are choices made by social actors and groups during the generation and implementation of new technologies. This process involves a set of conscious and unconscious choices between different technical options²⁸. Which options social actors select is affected by both technical considerations and a range of social and cultural aspects. Thus, social choices influence the contents of technologies. At the same time, technologies have social implications as they shape human action and behaviour²⁶. Following this, scholarly publishing practices can be understood as socio-technical ensembles: the ways in which scholarly outputs are published is affected by the operational choices made by scholars during the creation, implementation and use of respective communication technologies. These operational choices are influenced by both technical considerations and socio-cultural aspects. As communication technologies are implemented and used, they in turn affect the ways in which scholars communicate and disseminate their research findings. It follows that, in order to explain discipline-specific OA publishing practices, it is necessary to examine the socio-cultural and technical factors that affect publishing choices within particular disciplines. Based on these assumptions, we have developed an analytical framework that places focus upon technical factors and socio-cultural factors alike when analysing patterns of OA publishing practices. The analytical dimensions entailed in this framework are illustrated in Table 4.

Open access in the medical sciences

Initially, medicine and health-related disciplines were reluctant to adopt OA publishing, resulting in OA levels to be well below those observed in the natural and social sciences. From the mid-2000s onwards, however, the uptake on OA increased substantially and particularly biomedicine and clinical medicine took on leading roles in embracing OA. Research outputs are predominantly made OA by publication in Gold OA journals, whereas Hybrid OA, Bronze OA and Green OA are of little importance for these disciplines. Factors facilitating OA can be identified as strong OA mandates combined with either funder-operated repositories or available funding for article processing charges (APCs), the richness in high-quality and prestigious OA journals and the wide circulation of publications in these outlets. A major barrier to OA in the medical sciences are authors’ concerns over the quality of peer review in OA journals, which is related to the emergence of fraudulent journals and publishers.

A) Author behaviour and attitudes – Several surveys and interview studies have shown that in biomedicine and the life sciences, a large majority of authors support OA publishing, but the reputation of journals, their impact factor, and the quality and speed of peer review are more important factors determining the choice of publication outlets than the OA status^29–31. For example, in 2004, Sara Schroter and colleagues interviewed authors who submitted articles to the BMJ. Almost all authors supported the concept of OA, but many were concerned about poor quality research being published for a fee, and OA was not a factor of importance when selecting a journal³⁰. More recently, the 2014 international author survey conducted by publisher Taylor & Francis showed that investigators working in Science, Technology and Medicine (SEM) mentioned wider circulation than publication in a subscription journal as an advantage of OA, but were strongly against to the use of their work for commercial gain without their explicit permission³². Authors expected rigorous peer review and rapid publication in return for paying for OA publication^32,33. Surveys among academics from lower income countries indicate that the funding of APCs is an important concern^34,35. A study from India found that the most important factors influencing the selection of medical or dental journals were that the journal is indexed in widely used bibliographic databases, has an online submission system, a satisfactory impact factor and peer review, and that APCs are affordable³⁶. The importance of affordable APCs may explain why authors from resource-limited settings are over-represented among publications in fraudulent journals that charge small fees but do not provide proper peer review or add value through editing³⁷.

B) Publisher behaviour and policies – As private profit-oriented companies, most traditional publishers are driven by maximizing income to satisfy their shareholders³. Consequently, as the OA model is unlikely to generate the level of income and profit that can be achieved with the subscription model, few commercial medical publishers have converted their subscription journals to OA. This also applies to academic or professional societies²⁹. Policies on prior publication remain tight for most of these journals. Some journals have now moved to allowing their authors to self-archive submitted manuscripts without an embargo period, while self-archiving of accepted versions of a publication remains subject to a standard embargo period of 12 months. Pioneers among OA medical journals include the Journal of Clinical Investigation, which in 1996 became the first major journal to be freely available on the web. Of note, publication in the journal was free to authors initially, but APCs were introduced after the journal lost 40% of its institutional subscribers³⁸. The BMJ followed suit in 1998, but moved some content (including editorials and education and debate articles) behind a pay wall in 2005³⁹. The number of OA journals increased considerably from 2000 onwards, with the arrival and rapid growth of OA publishers such as the not-for-profit publisher Public Library of Science (PLoS) or the commercial publisher BioMedCentral (BMC). The launch of OA journals by major biomedical research funders^40–42 and the emergence of mega-journals are other factors that have influenced uptake of OA publishing in medical research fields⁴³.

C) Infrastructure of scholarly communication – OA publishing in the medical sciences focuses on Gold OA journals and only a small number of OA institutional and subject repositories has emerged. This can be explained as follows. First, sufficient funding is available for publication in Gold OA journals. Second, journal publications are of central importance in academic hiring and promotion decisions within the medical sciences. Third, there is a large number of high-quality Gold OA journals for authors to publish their research in. The uptake on open repositories in general is low, but an exception to this is the PubMed Central (PMC), which archives full-text scholarly articles and plays a central role in the medical and life sciences. PMC has experienced rapid growth in the late 2000s as the National Institutes of Health (NIH) introduced an OA policy that mandates its grantees to deposit the final peer-reviewed version of an article based on NIH-funded research in PMC. The embargo was initially 12 months after publication, but was later shortened to 6 months⁴⁴ and journals have since moved to be compliant with this Green OA mandate. Submissions into the PMC undergo indexing and formatting procedures, which produces advanced metadata and unique identifiers⁴⁵. Of interest, even though not of the same relevance as PMC, is also the PeerJ Preprint section, which allows authors to submit preprints and postprints from the biological and medical sciences.

D) Structural and institutional factors – The main type of work products in the medical sciences are journal articles. Like the natural sciences, research in the medical sciences and related fields in most parts is funded by project-specific grants, which makes it fairly easy to integrate processing charges for publication in OA journals into existing funding structures. Further, medical research is in large part funded by third-party funding, for example by the World Health Organization (WHO) and the Wellcome Trust. These organizations have strong OA mandates while, at the same time, providing both convenient open repositories for depositing articles and sufficient funds for covering processing charges for publication in OA journals⁴⁶.

E) OA mandates and policies – Evolving national and institutional OA policies, OA mandates by major funders of (bio-)medical research and the availability of funding for APCs have accelerated the uptake of OA publishing in the medical and life sciences. A substantial number of national governments have moved to require scholars in the medical and life sciences to make their articles OA if based on publicly-funded research by either publishing in OA journals or by making publications OA by depositing the accepted or the published version of an article in a repository. Usually, scholars are granted embargo periods of 6 or 12 months to comply with the latter¹⁸. Besides national governments and research institutions, major funders of medical research play an active role in promoting OA. Besides the NIH, this includes the WHO and the Wellcome Trust. Since 2014, journal articles and book chapters based on WHO-funded research have to be published in either an Gold or Hybrid OA journal or in a subscription journal that allows the author to deposit the accepted version in PMC no later than 12 months after publication⁴⁷. Similarly to the NIH, the Wellcome Trust requires articles to be published in OA journals where a journal makes this option available and to be deposited as the accepted version in an open repositories no later than 6 months after publication. Both funders state that they will withhold or suspend payments if articles are not made OA. Both funders provide repository infrastructures (PMC for NIH and PMC or PMC Europe for Wellcome Trust) and funds for covering APCs⁴⁶. In contrast to the USA, the policy environment in the UK favoured gold and hybrid OA, with particularly high uptake in the life sciences and rapidly increasing costs⁴⁸.

Open access in the natural and technical sciences

For most publication years, the natural and technical sciences show the highest OA prevalence rates amongst all disciplines. There are, however, substantial differences in the OA publishing patterns between different subdisciplines of the natural and technical sciences. Journals in the fields of physics, mathematics, astronomy, information technology and biology were the early pioneers of OA and continue to make large shares of their research outputs OA. In contrast, engineering and chemistry feature OA prevalence rates that are consistently much lower than in other fields of the natural and technical sciences and even slightly lower than OA levels observed in the social sciences and humanities. While Green OA seems to be of central relevance for OA publishing within physics, astronomy, biology, information technology and mathematics (followed by Bronze, Gold and, by some distance, Hybrid OA), scholars in chemistry and biology make larger shares of their research OA through publication in Gold OA journals than in open repositories. Factors facilitating OA in the natural and technical sciences can be identified as the long-existing culture of preprint distribution, availability in funding for APCs and high levels of awareness of and familiarity with OA publishing. Barriers to OA are concerns about the quality of OA journals and high degrees of industrial integration in some fields.

A) Author behaviour and attitudes – The distribution of preprints has a long tradition in many fields related to the natural sciences, particularly in physics, mathematics, astronomy, information technology and biology, where scholars commonly share their manuscripts before submitting these for publication to journals. Before it was possible to make documents available electronically, a paper-based culture of preprint distribution developed in the 1960s, especially in high-energy physics⁴⁹. With the emergence of the Internet, scholars began sharing electronic versions of their preprints informally via electronic mail and when Paul Ginsparg established the open repository arXiv in 1991, scholars started making their preprints openly accessible through centrally self-archiving them in arXiv⁴. Surveys have revealed that, to scholars within these fields, rapid publication, high visibility and large readership appear to be the most important factors when it comes to choosing a publication outlet, and that scholars associate these features with depositing preprints in open repositories^33,50. Adding to this, scholars in the natural sciences generally show high levels of familiarity with the concepts of OA in general and Green OA in particular^15,51. As a consequence, Green OA has become the most popular way of making research outputs OA in physics, mathematics, astronomy, information technology and biology. Publishing in journals (closed-access and Gold, Hybrid or Bronze OA) is less prominent for scholars within these fields. In contrast, scholars in chemistry and engineering value publication in journals over self-archiving in repositories, which is the reason why Gold OA plays a bigger role than Green OA in these fields⁵⁰. Despite the preprint culture in some of the natural sciences, 40% to 50% of all research outputs overall remain closed-access today. Chemistry and engineering show particularly low uptake levels on OA. This might be due to the fact that scholars within these fields still have concerns about the quality of peer review in OA journals and are concerned that this might translate into low-quality publications in these outlets. Consequently, OA journals within the natural sciences have not yet been able to match the reputation of subscription journals⁵².

B) Publisher behaviour and policies – Commercial publishers as well as learned societies in the natural and technical sciences have been slow in embracing the idea of OA. This relates to two factors: First, publishers face a potential loss of revenues in switching from a subscription model to an APC model, as has been shown in a number of market analyses^53,54. Second, general concerns about the quality of OA journals are not only shared by scholars but also by publishers and learned societies⁵². As a result, most of the major commercial publishers, as well as learned societies in the natural sciences, have been reluctant to either convert their existing subscription journals to OA and to set up new OA journals. An exception to this are few large publishing houses that have started setting up new OA journals in disciplines that do not have a culture of preprint distribution, such as chemistry or engineering. In disciplines where there is a culture of preprint distribution, publishers have started relaxing policies on prior publication and enable manuscripts deposited in repositories to be directly submitted to their journals⁵².

C) Infrastructure of scholarly communication – In physics, mathematics, astronomy, information technology and biology, scholars are used to sharing their research outputs openly making use of open repositories, particularly arXiv. Originally established within high energy physics, arXiv now is used by scholars in most fields of the natural sciences and its concept has eventuated in a number of discipline-specific repositories in other fields, including the social sciences. Even though repositories do not employ formal mechanisms of quality control, scholars within the natural sciences use them to first, disseminate their research outputs without publication delays, and second, stay informed about ongoing research within their fields⁴. In the light of this publication culture, relatively few OA journals have emerged within these fields. In fields where there is a smaller culture of self-archiving in repositories, most particularly in chemistry and engineering, the number of OA journals has grown slowly but steadily in recent years. These journals cover a variety of specific subject areas, are peer-reviewed, and, for the most part, are published in English. Exemplary journals in engineering are the International Journal of Antennas and Propagation, the Journal of Engineered Fibers and Fabrics, Journal of Scientific and Industrial Research and Thermal Science⁵⁵. Chemistry journals that enjoy popularity are the Archive for Organic Chemistry, Beilstein Journal of Organic Chemistry, Chemistry Central, Catalysts and ChemistryOpen⁵².

D) Structural and institutional factors – The main types of work products in the natural and technical sciences are journal articles, electronic preprints and conference proceedings, which are published records of conferences, congresses or other meetings. Researchers from the natural sciences have reported that the process of self-archiving electronic preprints and conference proceedings is little time-consuming and that they generally experience little difficulties in making research outputs OA using open repositories⁵⁰. In addition, and similar to the medical sciences, research in the natural sciences is in large parts funded by project-specific grants, which would make it fairly easy for scholars to integrate fees for publication in Gold or Hybrid OA journals into existing funding structures. A structural factor that limits the uptake on OA within the natural and technical sciences is that some of these fields, particularly chemistry and engineering, are industry-oriented. This adds to the fact that, particularly within engineering, the focus is rather national than international as products developed by engineers are, for the large part, produced for domestic markets. As a consequence of these factors, large numbers of publications within these fields are more practice- than science-oriented and are published in closed-access journals that are partly financed by advertising⁵⁵.

E) OA mandates and policies – Reflecting the ambition to make research outputs OA, there are strong OA mandates for the natural and technical sciences. Usually, these fields are subject to similar OA requirements as the medical sciences: scholars are usually required to make their outputs OA if based on publicly-funded research by either publishing in OA journals or by depositing the accepted or the published version of an article published in subscription journal in a repository. By default, scholars are granted embargo periods of 6 or 12 months to comply with the latter¹⁸. Besides national and international funding agencies, CERN and the Sponsoring Consortium for Open Access Publishing in Particle Physics (SCOAP) play leading roles in promoting OA. SCOAP is an international partnership of funding agencies, research centers and libraries that was launched with the aim of providing funding for the conversion of high-energy physics journals from a subscription model of publishing to OA. Within this scheme, libraries and research centers either pay reduced subscription fees for participating journals or stop paying altogether. Saved monies feed into a central fund, which is used to pay publishers up front to publish OA articles⁵⁶. Doing so, the initiative enables scholars to make their research outputs OA without straining their own research funds. By 2014, five journals had been converted within the framework of SCOAP⁴⁹. The OA policy of CERN requires its scholars to publish their articles, wherever possible, in journals covered by SCOAP. When circumstances require publication in journals that are not covered by SCOAP, the APCs must be covered by funds from outside the CERN Budget, for example through EU projects or by other institutions. Where this is not possible, authors may request special permission and funds from CERN⁵⁷.

Open access in the social sciences

Overall, the OA uptake in the social sciences is higher than in most disciplines of the humanities, but remains below the medical and natural sciences. Publishing in Gold OA journals plays a less important role than the archiving of publications in institutional and subject repositories following publication in a subscription journal. For scholars within the social sciences, open repositories appear to be of central importance for making research outputs openly accessible, closely followed by publication in Gold OA journals, and, with some distance, Hybrid and Bronze OA. The low uptake on OA is due to a variety of reasons, including low levels of awareness, concerns about quality and prestige of OA journals, the central role of monographs for career advancement and difficulties in accessing funding for APCs and Book Processing Charges (BPCs). Having said that, the social sciences are currently experiencing a cultural shift towards conducting science more openly, which manifests itself in an increasing embracement of OA.

A) Author behaviour and attitudes – Author surveys consistently have revealed that the awareness of OA publishing is lower for the social sciences than for the medical and natural sciences, and that OA publication outlets have not yet fully become part of the workflow for social scientists⁵¹. The knowledge of OA journals and repositories however appears to grow amongst social scientists with particularly young researchers reporting high levels of OA awareness and engagement⁵⁸. Most social scientists support the idea of OA in principle, but stringent quality control, further improvement of the manuscript before publication and journal prestige still appear to outweigh OA in authors’ journal selection criteria^59,60. As a consequence, OA publishing activity remains low for the social sciences. This is also due to the fact that some social scientists and their learned societies are still opposed to OA, which relates mainly to concerns about quality of peer review and editorial services in OA journals⁶¹. Relevant to the appreciation of OA in the social sciences is also the importance attached to monographs. While in the natural and medical sciences, the large part of research findings is disseminated via journal articles, the monograph has a central place in the culture and ecology of publishing in most of the social sciences and is highly relevant to career advancement^60,62. Monographs have been shown to be less likely to be published OA. Amongst other factors, this relates to authors’ concerns over restricted editorial services and doubts whether unestablished OA publishers and formats are able to translate their effort in writing a monograph into reputational gain within the scientific community⁶³.

B) Publisher behaviour and policies – Few publishers in the social sciences have decided to convert their existing subscription-based journals to OA or to set up new OA journals. Key academic journals in the social sciences remain closed access. Amongst other factors, this relates to publishers fearing that their academic authors will not be able to access funding for APCs or that switching to an APC model will result in a loss of prestige – both of which are main factors affecting authors’ choice of publication venue⁶⁰. For some journals, such as the Historical Social Research or the Zeitschrift für Soziologie, it has become common practice to make their contents automatically OA after an embargo period of two years either by enabling access to their articles on their own website or by depositing them in an OA repository⁶⁴. In addition to this, a large variety of new economic models of OA publishing has emerged that offers viable alternatives to author-payment model in the social sciences and humanities. To name only two, this includes Knowledge Unlatched (KU) and the Open library of Humanities (OLH). OLH is based on a business model that is called “Library Partnership Subsidy” and which asks libraries to pay a relatively small annual subscription fee to enable OA to scientific publications. The model originally was aimed at journals in the humanities and social sciences, but has been expanded to monographs⁶³. The goal of KU is to create a financially sustainable route to OA for monographs through a global co-operated model where libraries use their existing acquisition budgets to enable OA to monographs⁶³. Another innovative business model of OA publishing that has gained some popularity in the social sciences and humanities is the so-called “freemium” model. This model makes HTML versions of articles and books openly available to everyone, while PDF and ePub formats are accessible only to subscribing libraries and research institutes⁶⁵. One well-known example of this is OpenEdition. While long-term access to research outputs is questionable within these models, OpenEdition and others managed to convince otherwise conservative publishers to create open versions of their journal volumes and monographs⁶⁶.

C) Infrastructures of scholarly communication – The social sciences are currently experiencing a considerable growth of open repositories, resulting in authors being able to choose from more than 200 different OA repositories, the most of which are institutional or subject repositories⁶⁷. While subject repositories have become a fairly established part of the workflows for social scientists, institutional repositories are less often used and predominantly host faculty working papers and theses. Prominent examples of subject repositories are the Social Science Research Network, the Social Science Open Access Repository and SocArXiv. Because OA preprint repositories do not employ peer review, however, social scientists have been slow to adopt Green OA. Gold OA journals are of even less importance for the social sciences. Key academic journals in most countries remain closed access⁶⁸. The few existing OA journals in large part are restricted to highly specified sub-disciplines with limited impact and small readership. One notable exception to this was the launch of SAGE Open in 2011, which has brought to the social sciences the OA mega journal model already popular in the natural and medical sciences⁶⁹. In addition to this, a number of OA journals were launched by academic or professional societies, such as Socius: Sociological Research for a Dynamic World launched by the American Sociological Association in 2016⁵⁰.

D) Structural and institutional factors – Similar to most disciplines of the humanities, monographs are one of the main work products in the social sciences and highly relevant for academic promotion and career advancement. Besides author concerns over prestige and standards of editorial services of OA monograph publishers, the high costs and procedural complexities associated with producing monographs are important factors restricting the uptake on OA of monographs in the social sciences⁷⁰. In addition to this, social scientists have reported to face significant difficulties in access to grant funding for both APCs and BPCs, as most research in the social sciences is not done by means of project-specific funding that is commonly used to compensate APCs in the natural and medical sciences³¹.

E) OA mandates and policies – Scholars in the social sciences face similar OA requirements as scholars within the natural and medical sciences do. Some special regulations can be identified, however. First, monographs are generally not included in OA mandates. Most public funders limit themselves to recommending OA for monographs. One of the few exceptions to this is the SNSF, which demands the OA publication of monographs and provides respective funding for BPCs^63,71. Second, the social sciences commonly are granted longer embargo periods for the archiving of a journal article after publication in a subscription journal. While embargo periods of 6 or 12 months are the default for the natural and medical sciences, social scientists usually have to deposit journal articles in institutional or subject repositories after up to 12 or 24 months following publication^18,72.

Open access in the humanities

Generally speaking, OA uptake in the humanities is lower than in most areas of the natural, medical and social sciences. This is partly due to the fact that these disciplines exist in a “dry climate” of funding for gold OA models that rely on APCs⁷³. Low uptake is also due, though, to the fact that the monograph plays such a central role in many humanities disciplines, but the funding challenges for open access to such outputs remains an unresolved problem at scale^74,75. Hybrid OA is of central importance for the humanities, followed by Green OA, Bronze OA and Gold OA. Given that the humanities focus on the study of human cultures and artforms, it is, though, nonetheless surprising that more humanists do not seek to reach general public audiences through broader availability of their research work.

A) Author behaviour and attitudes – As in many academic fields, authors operate within a symbolic economy of prestige that is usually among the prime motivations in choice of publication venue⁷⁶. The relative prestige of publications is determined by a scarcity correlation (usually achieved through peer review) with the shortage of evaluative labour on hiring, tenure, and grant panels, although most humanities fields use an informal hierarchy of publications rather than quantitative measures such as the Impact Factor⁷⁵. Although institutional signups to the San Francisco Declaration on Research Assessment may help to change this through a shift to evaluation at the article level, the focus on the Impact Factor in that declaration may make it harder to alter evaluative cultures in these disciplines. Further, academics and learned societies in the humanities disciplines have often been opposed to open access, for a variety of reasons that range from concerns over misunderstanding, worries about open licensing and plagiarism, or fears for the standing of their members^77,78. In addition to this, humanities scholars show fairly low levels of awareness of OA and potential OA publication outlets in their fields⁷⁹. That said, there are signs of a cultural shift with new economic models that do not rely on author payments, such as KU, the OLH, Open Humanities Press, Open Book Publishers, Punctum Books, and others appearing to have some traction with at least some humanities scholars. Although it is tempting to posit that humanities scholars are simply less driven by technological change than their counterparts in scientific disciplines, and thereby less inclined towards digital (and, therefore, open) publishing solutions, this is a generalized assertion that is hard to substantiate.

B) Publisher behaviour and policies – The main concern driving humanities publishers is ongoing sustainability of their operations. In switching to an APC or BPC model, often undifferentiated from scientific publications, publishers fear that their academic authors will not be able to pay. It is also clear that highly selective publication models, which are common in the humanities, are more difficult to run, economically, on an OA basis. Hence there is little movement towards a fully gold OA ecosystem, although it is unclear what impact the recently announced pan-European initiative, Plan S, may have upon this. That said, most humanities publishers are compliant with green OA mandates, such as the UK’s REF policy⁸⁰. On the other hand, it is also the case that some humanities scholars have argued that a longer citation half-life (particularly for monographs) should translate to longer embargo periods within these disciplines, although this does not necessarily match up to sales half-lives⁸¹. Despite some disciplines having healthy cultures of offline working paper circulation (philosophy, for instance), preprints have not taken off in the humanities and policies on prior publication remain tight, especially in the most prestigious venues.

C) Infrastructure of scholarly communication – In addition to institutional repositories, there has been a growth in recent years of OA subject repositories, such as the MLA Commons, which is operated by one of the largest subject associations in the humanities. There has also been a prominent culture, for many years, of scholar-led OA journal and book publications⁷⁶. Postpublication peer-review remains rare and usually elicits scant participation without active intervention, with a few notable exceptions and experiments^82,83. There is no infrastructure at a comparative scale to arXiv in the humanities disciplines. Furthermore, for long-form reading, print remains a crucial resource and scholars often report that they do not wish to read works of 80,000-words length in a purely digital format.

D) Structural and institutional factors – The high costs of producing monographs are a key structural factor that currently limits OA in the humanities^62,70. Further, most research work in the humanities does not receive project-specific funding, making it difficult to integrate processing charges into a grant. That the humanities disciplines are often of lesser importance in institutional hierarchies also means that it can be difficult to secure funding for articles. The slow cycle of producing long-form outputs is also problematic for OA, as the time investment (and hoped-for credit on publication) is greater than those of a journal article, leading scholars into more conservative prestige-seeking behaviours. There are also substantial challenges around third-party rights and re-use of images, particularly within disciplines such as Art History. Museum policies on licensing have not kept pace with digital publication practices and still often rely on “number of copies” as a metric determining pricing for re-use. Under such a paradigm, it can be difficult (or very expensive) to negotiate re-use rights for unlimited online dissemination. Finally, some disciplinary spaces, such as creative writing, have developed outward facing cultures that rely on sales. Creative writing scholars are often assessed on whether they can produce a “bestselling novel”, which works poorly under an OA model. The production of such artifacts may, however, have a research process behind them and various institutional policies will regard such objects as scholarly undertakings. The extent to which such work should be exempted from OA mandates remains, therefore, an ongoing debate.

E) OA mandates and policies – In national cultures, such as that in the UK, the humanities are subject to similar OA requirements as the social sciences, involving monographs being excluded from OA mandates and embargo periods of 12 or 24 months for the archiving of journal articles after publication in a subscription-journal. A few research foundations, such as the Wellcome Trust, will pay for Gold OA to monographs in the medical humanities. It appears likely, given recent moves among European funders, that policies around lengthened embargo periods for the humanities will be harmonized with other disciplines down to zero in coming years.

Open access in law

The transition to OA of legal literature can be said to be still in its infancy. Legal studies feature some of the lowest OA prevalence levels. In part, this is because of low levels of awareness and little demand for OA publishing outlets amongst legal scholars and practicing lawyers. Those who would most benefit from the OA movement (e.g. law schools unable to subscribe to a wide range of law journals and practitioners in smaller law firms) have little influence over publication behavior. Further, despite the rising importance of international law, the relevance of national legal systems remains high, causing most law journals and law books to focus on the legal situation in a specific country and to be managed by publishing houses in that same country. Often, legal scholars know their publisher(s) personally and tend to publish in a relatively small number of journals -– most of which are closed access.

A) Author behaviour and attitudes – Generally speaking, legal scholars have been reluctant to adopt OA despite agreeing that the research field would benefit from journals that publish OA articles^84–86. Even though the field is slowly moving towards OA, many authors of legal publications either are not aware of OA or have little to no incentive to publish their research in OA journals or public repositories⁸⁷. In legal studies, it is common practice that academics and practicing lawyers publish in the same legal journals or legal commentaries. Some practicing lawyers might even prefer to publish in law journals behind paywalls, thereby guaranteeing an exclusive access to their knowledge and ensuring that potential clients are not able to find the relevant information themselves⁸⁸. Because of the high relevance of national legal systems, large parts of the legal literature is written in the languages of these countries and published in law journals or books operated in the same countries. Accordingly, the argument that OA enables a worldwide readership is of limited relevance in the field of law. On the other hand, many legal issues are of interest not only to academics and practicing lawyers, but also to the media and politics. According to Hunter (2005), scholarship in law “is arguably the most useful to the public and that has the greatest effect on public policy”. The role of electronic media in supporting scholarly communication and dissemination of research findings is growing but the most important databases (e.g. HeinOnline and LexisNexis in the United States or BeckOnline in Germany) are paywalled⁸⁹.

B) Publisher behaviour and policies – In the U.S., many or most law reviews are published by law schools, not by for-profit publishers^89–91. In contrast to commercial publishers, law schools do not have the usual incentives to oppose OA. Hence, a large and growing number of US law journals are OA. The situation is very different in jurisdictions outside the US where legal scholarship is generally published by commercial publishers^84,91. Due to the small demand for OA publishing on part of legal scholars, there are little to no incentives for for-profit publishers to set up new OA journals or book series or to convert existing subscription-based journals to OA. There are some notable exceptions, however. In recent years, some OA law journals have been set up that are predominantly community-driven and operated independently from commercial publishers (e.g. JIPITEC in the EU, Forum Historiae Iuris in Germany or sui generis in Switzerland). According to the DOAJ, there are about 200 OA law journals. OA law journals from the US are in large part not listed, although it is not clear why this is the case. The Creative Commons list of OA Law Adopting Journals lists 37 OA law journals but most of the 18 Harvard Law School Journals (all but one of them are OA) are missing⁹².

C) Infrastructure of scholarly communication – Most OA journals and open repositories are operated by universities and their law departments. Most universities in the U.S. have their own repositories and also publish their own legal OA working paper series. This idea gains some traction in other countries, for example in Germany, the Netherlands or Italy. Prominent examples of universityled OA journals involve Stanford Technology Law Review, Harvard Human Rights Journal, Bucerius Law Journal or the International Journal of Communications Law & Policy. There is only a limited number of disciplinary repositories and the uptake of repositories such as LawArXiv appears to be slow. In the US and in international law, the most popular disciplinary repository for law professors is SSRN, which is now owned by Elsevier. In English-speaking legal scholarship, scholars find it even difficult to build reputation without being represented in SSRN⁹³. A growing number of universities is further providing support for setting up OA journals or transforming closed to OA journals (for example, by providing an OJS infrastructure). Since practicing lawyers and legal scholars work almost exclusively with texts, OA infrastructures do not have to fulfill demanding technical requirements.

D) Structural and institutional factors – There are three types of work products in legal research: monographs, journal articles and commentaries covering a specific law. PhD theses in the field of law are predominantly published as monographs. Many universities routinely make PhD theses OA (for example Harvard University in the U.S. University of St.Gallen in Switzerland). While the authors of legal books are mostly academics, this remains different for journal articles and legal commentaries where both academics and practitioners contribute. As a result, not only scholars and universities, but also practicing lawyers need to be convinced to move towards OA. One possible way to foster OA amongst legal scholars might be to encourage academics and practitioners to publish in different journals and commentaries. In this scenario, academics could publish their works in scientific OA journals and practitioners could keep on using closed access journals and commentaries, which, however, would be more practice-oriented. Research project costs often are smaller in the field of law compared to other disciplines. As legal scholars are not dependent on third party funding, so that funder OA requirements have only limited potential to incentivize OA publishing.

E) OA mandates and policies – OA mandates by public funding agencies, research foundations and private companies only have limited impact in the field of law since legal research is relatively inexpensive and therefore does not depend on third party funding in large parts⁹⁰. As law is often considered as a discipline related to the humanities, scholars in this field face the same OA requirements as the social sciences and humanities, including relatively long embargo periods for Green OA and monographs that are excluded from OA requirements. It can be assumed that OA mandates by universities, if mandatory, will have a greater potential to foster some change in the field of legal academia than OA mandates by public funders. An important alternative to top-down OA mandates are OA policies from law schools (for example the Harvard Law School Open Access Policy) and non-binding statements promoting OA. In 2009, the directors of the law libraries of 12 US Universities signed the Durham Statement on Open Access to Legal Scholarship. This statements urges law schools to make the definitive versions of journals and other scholarship produced at the school immediately available upon publication in stable, open, digital formats, rather than in print⁹⁴.