Designing Tools for High-Quality Alt Text Authoring

four subimages (a) the free-form authoring interface. the traditional alt text editing pane with the addition of bullets before the text box. the bullets say: “the subject(s) in detail, the setting, the actions/interactions, and “other relevant info” (b) the template authoring interface. an interface pane with 4 prompts each followed by an individual text box. ( c) and (d) the feedback interfaces below an image asking acceptable, unacceptable or offensive.
Caption: Interface variations that we tested with alt text authors: authoring interfaces (top) and feedback interfaces (bottom).

Results and Discussion

Differing alt text preferences among people using screen readers

Our SRU interviewees reported the characteristics of alt text that were most important to them. Some traits were widely shared among all interviewees, including accuracy (i.e., no incorrect information) and completeness (i.e., no important information is omitted). Other characteristics varied between individuals, including use of natural-sounding language (as opposed to machine-generated language), conciseness, and detail. These latter two characteristics are often in opposition of each other. For example, the two most preferred alt texts for an image of a person drinking coffee were:

Author experiences creating alt text with and without interface variations

Before testing our interfaces, alt text author interviewees reported trouble knowing what to include in alt text: “What’s alt text versus what’s a caption? I don’t really know … [I’m not sure] what kind of context to put in it, [and] where to begin and end.” After using our interfaces, participants felt more supported in writing alt text: “It’s kind of nice to have that detail … so you’re just not out there, like ‘what should I put?’” At the same time, the alt text generated with our interfaces was more frequently of higher quality than that created with the traditional PowerPoint interface, both according to an existing quality scale and reports from SRU interviewees. While the more structured template-based interface was considered more tedious by experienced alt text authors, less experienced authors preferred the more structured template.

Feedback interface outcomes

Our author interviewees generally appreciated the feedback interface, where alt text could be marked acceptable, unacceptable, or offensive. They found the interface quick and easy to use, with most preferring icon-based feedback over checkbox. Preferences around location were split, some preferring closer proximity to the image and others preferring it to be separate in a side pane.

Automatic alt text views and effects

Finally, we found that author interviewees preferred to have the alt text authoring area prefilled with automatic alt text generated by AI. Even though several authors commented on the inaccuracy of the alt text, they preferred to have it since removing it was of little cost and it helped them feel more supported: “ … it makes me feel like somebody is helping me and I like that because I’m more inclined to put the effort into it because I’m like, ‘Oh, you don’t have to do it alone.’”



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Kelly Mack

Kelly Mack

PhD Student at the University of Washington