The Effects of "Not Knowing What You Don't Know" on Web Accessibility for Blind Web Users

Web accessibility and usability have been extensively studied for blind web users. The focus has generally been on making it technically possible for blind users to access content, or on helping to make the web more usable. This paper explores a challenge at the intersection of these two lenses, which is the effects of blind web users not knowing what they don't know. On the web, this often means that the user is having a problem completing a task, but does not know whether the problem is because the information is there and not accessible, whether the information is simply difficult to access, or whether the information is not present at all. We first discuss how this issue has manifested itself in other work in this space. We then present the results of a study with 30 sighted web users and 30 blind web users exploring the phenomenon, demonstrating that not knowing the source of a problem causes frustration and wastes time. We conclude with recommendations for future research to help understand and address this problem, as well as design implications for future technology that may assist non-visual web navigation.