Why You Need to Add Alternative Text to Visuals

For many professors, this summer will involve going through every PowerPoint slide in our lectures to add alternative text (alt text) to every figure, illustration, table, picture, and graph to make the slides accessible. If you haven’t yet thought about doing that, you probably should. Many institutions of higher education across the country have been sued for a lack of accessibility. Here’s a list of many of them: Higher Ed Accessibility Lawsuits.

Writing alternative text can be quite challenging, because the text must convey both the content and the function of the visual in just a few words, or a sentence or two. For those of us in science, this presents a significant challenge when the figure explains a complex process such as cellular respiration or lists every artery in the human trunk, for example. Exactly how much information is enough, and how much is too much?

One thing to keep in mind is that images only help students who can see them. The alt text is necessary to indicate to a screen reader, and hence the person using the screen reader, what the image is, because screen readers do not know what images are. They cannot “read” them.

Another problem for those of us in the sciences is that our discipline is incredibly visual and often uses color in identification and interpretation. For a student who has never seen, color is meaningless. So think of other ways of describing and differentiating within images when adding alt text.

The primary thing to remember is that alt text should be brief. If an acceptable description of the image’s content is contained in the textbook that references the image, then the alt text need only briefly indicate the content and function of the image. Alt text should not repeat what is already written in the text. If no description exists, a detailed description still does not belong in alt text. The alt text should indicate where a long description exists. Here’s a website that helped me determine how to add appropriate alt text: Alternative Text.

Beyond that, we are pretty much on our own to make the determination of what information is necessary and sufficient. If possible, ask a student who regularly uses a screen reader to listen to the slides and offer feedback. Otherwise, remember that the student will be listening to the information, so close your eyes and have someone read the alt text to you. Does that description adequately and succinctly indicate the content and function of the image?

Importantly, once alt text has been added to all images it’s necessary to make sure tactile graphics, Braille-labeled models, and/or dissection specimens, etc., are available for the student to manipulate. That is how the student with a visual impairment will be able to learn the information he or she could not learn from the image. Some companies will make tactile graphics for textbook visuals. They’re expensive, however, and normally take a long time to complete.  So unless you have a lot of prior notice, they may well arrive later in the semester.

With the newest upgrade of Microsoft Office for Mac, most of us now have access to built-in accessibility checkers in Microsoft Word and PowerPoint on both PCs and Macs. A note of caution about using those accessibility checkers for your figures, illustrations, etc.: When an image is downloaded from the Internet, it is sometimes tagged with alt text associated with the search string. So if that image resides in Word or on a PowerPoint slide, the accessibility checker will not flag that image as needing alt text. However, the alt text is often not appropriate in the context in which the image is being used. Further, some textbook publishers have added alt text that lists only the Figure or Table number of the image. While that information could be helpful, it would not convey the necessary information about the image. Always make a habit of checking the alt text of every image.

Once you’ve determined what to write, how do you add alt text?  I think the easiest way is to right click on the image and choose Format Picture.  In the drop down menu you should see “Alt Text” listed.  You don’t need to add a title.  Just type the alt text into the Description area.

Back to grading now…

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