Cognitive Disabilities
Design Considerations
Overview
Individuals with cognitive or learning disabilities may use a wide variety of technologies to adapt or simplify content to their needs. Text-to-speech, screen readers, customized fonts or page colors, text simplification, and other techniques might be used. Even though such technologies are available, authors must also consider the design of their content to minimize cognitive difficulty.
The ideas below present some of the larger principles for addressing some of the needs of users with various cognitive or learning disabilities. They are intended for use in conjunction with general usability principles and techniques (which lie beyond the scope of this article).
Accommodating Memory Deficits
Reminders of overall website context can help people with memory deficits. Lengthy or complex processes, like browsing/searching for and purchasing items online, should be kept as simple and brief as possible. To focus the users' attention on specific tasks, the interaction might be broken up into separate pages, with progress indicators such as "step 2 of 4" to help them keep track of what they have already done and what they have left to do. Instead of saying merely "previous page" and "next page," links should say "Back to payment and shipping information" and "Next: review order."
Accommodating Problem-Solving Deficits
Anyone can click the wrong link, misspell a word, or leave a required form field empty. In some individuals, this tendency is exaggerated. Error messages should explain what is incorrect and show how to fix the problem. Search features should suggest alternate spellings to users if the original spelling seems suspicious or if it returns no results. Users should be forewarned of significant actions such as deleting a file or committing to an irreversible financial transaction. Instructions at the beginning of a task help prevent user errors.
Avoid unexpected changes in website context. Functionality should be as predictable as possible, with deviations accompanied by warnings or explainers.
Authentication processes that require completion of a cognitive function test, such as completion of a CAPTCHA puzzle, should include another method for authentication, such as two-factor authentication.
Accommodating Attention Deficits
Help users focus their attention. Use visual cues to highlight important points or sections of content. If possible, eliminate animation, advertisements, and sponsored links. Use headings to draw attention to the important points and outline of the content. Avoid background noises or images that distract. Use them instead to focus the user's attention.
Accommodating Reading, Linguistic, and Verbal Comprehension Deficits
Supplemental media
Supplemental media such as illustrations, icons, video and audio can greatly enhance accessibility for people with cognitive disabilities. The problem is that high quality media is often difficult to produce. Poor quality media can actually create accessibility barriers by making content more confusing. Apply usability principles and your own judgment and get feedback from others if possible. Incorporate media where it makes sense. Realize, too, that most web content could benefit from some sort of supplemental media, if only supplemental graphics.
Document organization and structure
Structural organization
In general, the more structured your document is, the easier it will be to understand. Document structure can be defined via these methods, all of which are built into HTML:
- headings (
<h1>,<h2>,<h3>, etc.) - lists
- numbered lists
- definition lists
- regions/landmarks (
<nav>,<main>,<footer>, etc.)—most useful to screen reader users
Visual organization
Visual structure also helps sighted users. For example, you can:
- indent sub-items in a hierarchical list
- highlight items by changing the font color or background color
Be sure to consider HTML semantics when working toward a visual effect. Even though <blockquote> or HTML lists indent text, these should not be used just to indent text—only if the text truly is a quote or list. Otherwise, CSS should be used to achieve the desired visual presentation.
White space
Text is usually easier to read when it is visually separated from the borders of the surrounding design. White space especially helps people with reading disorders such as dyslexia. This includes space between headings, paragraphs, tables, etc. Long paragraphs can be more difficult to read than shorter ones, partly because readers may lose their place within the paragraph.
Clear and simple writing
Short, simple, unambiguous phrases are the easiest to understand. People with more profound cognitive disabilities need very clear and simple writing. In some cases, they will not be able to understand sentences at all, relying completely on graphics, illustrations, and other non-text visual materials. This does not mean that you have to create image-only sites for general audiences, though adding high-quality supplemental illustrations is helpful. If, however, your primary audience is individuals with more severe cognitive disabilities you may need to create image-only content or versions of content.
Try to avoid non-literal content such as sarcasm, parody, and metaphors. Also make sure to give readers all necessary background information about the topic at hand.
Accommodating Math Comprehension Deficits
Mathematical computations and formulas can be difficult for many people to understand, whether they have a specific deficit in math ability or just general discomfort with the subject. Authors can increase the understandability of their content by avoiding math or by explaining the math conceptually.
Accommodating Visual Comprehension Deficits
Usually, the best advice to help users with cognitive disabilities is to provide information in multiple formats, with a heavy emphasis on visuals. However, some cognitive disabilities cause difficulties in visual comprehension. If authors rely entirely on visual communication methods, the message will miss some users. Visual communication methods include color, spatial relationships, styles, typography, design elements, photos, images, etc.
Even though most web content suffers for a lack of visually-enhanced communicative methods, no single method is sufficient by itself. Be sure to supplement the information with multiple modes and methods of communication, and ensure that page content is adaptable to user styles, such as overriding page colors, fonts, text spacing, etc.