  Scholarly journals are increasingly using social media to share their latest
research publications and communicate with their readers. Having a presence on
social media gives journals a platform to raise their profile and promote their
content. This study compares the number of clicks received when journals
provide two types of links to subscription articles: open access (OA) and paid
content links. We examine the OA effect using unique matched-pair data for the
journal Nature Materials. Our study finds that OA links perform better than
paid content links. In particular, when the journal does not indicate that a
link to an article is an OA link, there is an obvious drop in performance
against clicks on links indicating OA status. OA has a positive effect on the
number of clicks in all countries, but its positive impact is slightly greater
in developed countries. The results suggest that free content is more
attractive to users than paid content. Social media exposure of scholarly
articles promotes the use of research outputs. Combining social media
dissemination with OA appears to enhance the reach of scientific information.
However, extensive further efforts are needed to remove barriers to OA.
