Prewriting Alternate Text for Images
by Guest Bloggers, Daniel Spillers, system administrator Aaron Baker, data analyst —
We have covered how providing video transcripts can improve accessibility for all content consumers and at the same time lead to better teaching through “pre-captioning”. But due to the greater effort involved in producing videos, it is much more likely that static images are used to enhance written content. Image choice can affect audience attention and comprehension, especially in presentation slides that might accompany a lecture. A carefully selected image can reinforce a concept instantaneously, similar to the way experience or the act of doing is often the shortest path for learning. Instructors use imagery as a kind of cognitive shortcut, and the omission of alternate text for such imagery—especially in an online course environment—removes that shortcut for blind students.
Because producing original imagery from scratch can be complex, an instructor may be tempted to use clip art—pre-made imagery created to be as broadly applicable as possible. Clip art often becomes more about visual decoration than aiding comprehension, and so it becomes a lazy choice. We can support this claim through the process of trying to write alternate text for most clip art. After providing a description of a piece of clip art, assess the information contained in that image. Is that information vital to understanding? Does providing that clip art create a cognitive shortcut tied to the rest of the content on the page? Or is it just a smiling man with a dog?
Alternate text for imagery does more than provide equal access to information—the act itself can help the instructor validate that their image choice has purpose and true value to the student. Alternate image text becomes a metric for the strength or weakness of an image choice.
When you write alternate text for an image, you are not trying to explain what the image means or why the image is there. A blind reader has all the other context that sighted readers have. Blind readers are only missing the visual details of the image that would provide the comprehension shortcut described before. But which details are the critical ones so that the same comprehension occurs for an audience of differing ability?
If the details are easy for an instructor to provide as alternate text, then your image is likely a strong choice. This may be due to data or additional text provided in the image (e.g., a chart or graph), or simply the inherent power of an image to convey more than words can alone. The act of writing alternate text justified your choice.
If the details are difficult to compose or unhelpful, then the instructor now has an opportunity to reassess the image choice. In fact, this judgment might result in what the text should be, which might in turn point the way to a better image choice.
But writing alternate text does not have to be an additional step after an image has been chosen. When putting together materials, an instructor could develop the practice of using placeholder text to help inform image choice. The use of placeholder text lets an instructor record the visual details a “to-be-determined” image should contain as part of the early composition process. That text then helps select an image with cognitive value and can be used as alternate text in a single step, removing the most serious barrier to providing accessible visual content within curriculum: time.
Understanding Universal Design for Learning is part of a semester-long Learning Shorts series on Accessibility and Universal Design in conjunction with the Department of Educational Leadership, the Disability Resource Center, and Scholarly Technology and Resources (STaR).