Communicating Visualizations without Visuals: Investigation of Visualization Alternative Text for People with Visual Impairments
This work addresses information access inequality for people with visual impairments by improving visualization alternative text, though it is incremental as it builds on existing guidelines and practices.
The study investigated how alternative text for visualizations can better serve people with visual impairments by consolidating guidelines, surveying practices, and interviewing 22 participants, finding that users prefer referencing underlying data over visual elements to reduce cognitive burden and enabling tasks like value retrieval.
Alternative text is critical in communicating graphics to people who are blind or have low vision. Especially for graphics that contain rich information, such as visualizations, poorly written or an absence of alternative texts can worsen the information access inequality for people with visual impairments. In this work, we consolidate existing guidelines and survey current practices to inspect to what extent current practices and recommendations are aligned. Then, to gain more insight into what people want in visualization alternative texts, we interviewed 22 people with visual impairments regarding their experience with visualizations and their information needs in alternative texts. The study findings suggest that participants actively try to construct an image of visualizations in their head while listening to alternative texts and wish to carry out visualization tasks (e.g., retrieve specific values) as sighted viewers would. The study also provides ample support for the need to reference the underlying data instead of visual elements to reduce users' cognitive burden. Informed by the study, we provide a set of recommendations to compose an informative alternative text.