It's widely known in the blogging community that alt text on images is very important for accessibility. It may come as a surprise that Create List images have alt text set to none by default. In this article, we will cover the important reasons why alt text is not required for images in a List card.
Alt Text and Decorative or Navigation Images
The images in a List are considered "navigation images," or "decorative images." The main purpose of these images is for aesthetic appeal on the page, and they don't really add information to the post's content. Sometimes, these images may even be unrelated to the information in the post itself.
In your List card, a user can read the title, description, and link with their screen reader, which will tell them where the link goes. That provides needed context so they can decide whether to click and get more information (including full-size images with alt text). For these reasons, the best practice is for alt text to be set to none.
With accessibility, everything is contextual, and there can be cases where providing too much information can be detrimental to the user's experience.
Regarding decorative images, the Web Accessibility Initiative notes, "Text values for these types of images would add audible clutter to screen reader output or could distract users if the topic is different from that in adjacent text."
When Create List Images are Called Out in Accessibility Tests
Accessibility testing tools are popular to help site owners stay ADA compliant. While these tools can be helpful guides, they typically are just calling out anything that may need attention without taking context into account.
A lot of these tools will call out any image without alt text. Based on the context, though, some images should ideally not have alt text according to web accessibility guidelines.
We recommend deferring to Google Lighthouse when possible and referring to other accessibility testing tools mainly as a general guide.