For a student who is visually impaired, alt-text descriptions are very important pieces of information. And when these descriptions are well-written, they can provide information just as effectively as the image they describe. So what makes an alt-text description effective? Here are five important characteristics they share:
1. Overall Brevity
It’s important to remember that an alt-text description will be “heard” and not “seen.” Because of this, the description should be as short as possible while still describing all of the critical information. A shorter description is easier for the listener to process than a longer one would be. If a description gets too lengthy, the listener’s attention might waver, and they may get confused.
2. Short, Simple Sentences
Not only should the overall description be as concise as possible, but the sentences themselves should be short and simple. Typically, long sentences can be split into two or more short sentences that will be easier to understand and process. Also, the description should try to avoid repeating lengthy words or phrases over and over again.
3. Brief Summary Followed by Specific Details
For images that are complex, the description should begin with a quick summary of the image and its structure, followed by more details about the various components of the image. For example, the description of a computer network could start with an overview of the overall configuration before moving on to specific descriptions of the various devices on the network.
4. Does Not Interpret or Explain the Image
An alt-text description should only attempt to describe the image as it would present itself to a visual reader. A person who can see the image must still draw their own conclusions from the information they see. If the alt-text description attempts to perform this analysis, it only detracts from the learning process. For example, the description of a chart showing company revenues for various products should not try draw conclusions about which course of action should be taken as a result of this information.
5. Does Not Include Extra Information
A description should omit information that, while present in the image, really isn’t critical to understanding the message. For example, an image might use colors to help distinguish or highlight different areas. However, specific color names may not mean anything to a visually impaired person, so it’s best to avoid them unless the colors themselves represent critical information. Similarly, it may not be necessary to describe basic shapes like boxes or bubbles (often seen in flowcharts or other similar graphics) because they are simply objects containing text inside. In those situations, it should be sufficient to include only the text contained within each shape.
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