Empowering Accessibility: The Power of Words in Making Visualizations Speak for Everyone

Summary: Communicating Visualizations without Visuals: Investigation of Visualization Alternative Text for People with Visual Impairments investigates how the use of alternative text descriptions can enhance the accessibility of visualizations for people with visual impairments, making complex data and graphics more comprehensible through the power of words.

Have you ever considered a chart or graph might look to a visually impaired person? How do you think they understand significant details of a line graph or grasp the importance of different colors in a pie chart? These questions underscore the critical need for inclusivity in data visualization. Visualizations such as charts, diagrams, infographics are incredibly crucial in conveying information in a compact and concise way; however, these are often inaccessible to those with visual impairments.

The 2021 study, “Communicating Visualizations without Visuals: Investigation of Visualization Alternative Text for People with Visual Impairments,” looks at how alternative text can revolutionize the way people with visual impairments access and comprehend visual data. Instead of relying on colors, shapes, and patterns to convey information, by using detailed written alternative text, individuals with visual impairments can better engage with complex data sets and derive meaningful insights from visualizations once inaccessible to them.

Take, for example, a line graph illustrating the population growth of different countries. While the visual representation might portray an upward or downward trend, alternative text could describe the significant shifts, the countries experiencing rapid growth, and the ones stagnating. By providing rich textual context, individuals with visual impairments can form a clear mental image of the visualization.

There are a few guidelines that offer recommendations for generating alt text to visualizations.

Structure of alt text

The Web Content Accessibility Guidelines recommends providing two descriptions; one short description in the alt text with information on how to access a longer, more detailed description.

Components in alt text

Striking a balance between clarity and descriptive detail can be achieved by including a one-sentence summary of the chart, chart type, and axis labels. Presenting scales and values, along with a summary of data trends can also be helpful.

Data tables

For complex visualizations, the US government Accessibility for Teams page suggests to “consider complementing the graph with a table of information so that it can be read more easily by screen reader users and when compressed to mobile.” Similarly, Harvard’s handy page on digital accessibility suggests that textual descriptions are not beneficial to only the visually impaired: “People learn in different ways — some might be visual learners while others prefer a more analytical text-based approach. Presenting data in multiple formats will ensure that people can digest the information in the way that best suits their needs.”

Webaim’s infographic on Web Accessibility for Designers is a perfect example of an infographic that follows the three guidelines.

Besides the infographic, the page includes a text version in the form of a table, additional links that provide more information, and an embed code for users to embed the infographic into their pages.

Further details can be found on Harvard’s page on writing good alt text; “you need to think about the information that the graphic conveys, such as the categories of data being shown, trends, and maximum and minimum values.”

For example, an effective alt text on a graph titled “Media Sources for the Iraq War” would be:

“Analysis of media coverage during the Iraq war was by no means universally objective. In fact, it’s clear that coverage was overall pro-war with American news sources being slightly more pro-war than sources from outside the US. Neutral coverage came in at 26%, while a minority of sources were determined to be anti-war. Only 3% of American sources fell into that category.”

In today’s data-driven world, accessibility should be a fundamental principle. Strategies for communicating complex information should be reassessed constantly, starting by incorporating alternative text descriptions as an integral part of our communication toolkit. Does the alt text describe the information in the context of the entire page? Do they provide enough information for the page to make sense without the visualizations? For tools on checking general accessibility of a webpage, Harvard has compiled free automated tools to check for if a page makes sense without its visualizations.

The true power of information lies in its accessibility; in the age of data, let’s not forget to be open to the diverse ways in which people perceive and understand information.

Citation:

Jung, C., Mehta, S., Kulkarni, A., Zhao, Y., & Kim, Y.-S. (2022). Communicating visualizations without visuals: Investigation of visualization alternative text for people with visual impairments. IEEE Transactions on Visualization and Computer Graphics, 28(1), 1095–1105. https://doi.org/10.1109/tvcg.2021.3114846