Communicating Visualizations without Visuals: Investigation of Visualization Alternative Text for People with Visual Impairments

Abstract

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.

Striking a Balance: Reader Takeaways and Preferences when Integrating Text and Charts

“…Finally, participants completed the demographic section. Here, they reported their age range (e.g., [18][19][20][21][22][23][24], their current education level (e.g., "Less than high school"), and their experience with charts and reading. This experience was captured through both the frequency (e.g., "Every day") as well as the context in which they engaged with the material (e.g., Government reports).…”

“…The W3C Web Accessibility Initiative (WAI), visualization practitioners, and publishers of accessible media have produced a variety of guidelines for what these textual representations (referred to as alternative text or alt text) should seek to convey, including the chart type, axes and labels, and summaries of the overall trends [5,53,55]. Building on these guidelines, Jung et al surveyed and interviewed BLV people to find that alt text is often the only interface to the depicted data; poor quality text can increase inequities in information access [20]. The researchers further recommended that alt text should be structured to ground the textual representation in the underlying data rather than the visualized elements to reduce readers' cognitive burden.…”

“…A subset of the population prefers text-only over text alongside a visualization; when designing a presentation or performing studies of different visualizations, consider a version of the text that can stand on its own. This text can also be a useful starting point for story-centered textual annotation and provide accessibility benefits [20].…”