Any list of design considerations for users with cognitive disabilities can easily turn into a lengthy list of usability concerns and general "good design principles." The ideas presented here do not exhaust all avenues of thought on the topic, by any means. They merely present some of the larger principles which categorize more specific techniques.
Accommodating Memory Deficits
Any kind of reminder of the overall context of a web site can help people with memory deficits. Lengthy interactive processes, such as those required to purchase items online, should be kept as simple and brief as possible. To focus the users' attention on specific tasks, the interaction should probably be broken up into separate pages, but help users keep track of their progress so they do not get lost in the process. Simple reminders such as "step 2 of 4" help them keep track of what they have already done and what they have left to do. Each step can also be named or labeled so instead of saying "previous page" and "next page," a link could say "previous page (payment and shipping information)" and "next page (review order)."
Accommodating Problem-Solving Deficits
Everyone at some point or another accidentally clicks on the wrong link, misspells a word, or commits some kind of error on the web. This is normal human behavior. In some individuals, this tendency is exaggerated, so they make even more mistakes. Whether people make many or few mistakes, everyone likes to be able to correct their errors. Error messages should be as explanatory as possible, telling users what they did wrong and 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 warned when actions can cause potentially serious consequences, such as deleting a file. In many cases, providing instructions at the start of a task will eliminate or at least reduce the overall number of user errors. Also, avoid extreme changes in the context of the web site without first warning users. All functionality should be as predictable as possible, and any deviations from predictability should be preceded by warnings and/or explained to users after the changes occur.
Accommodating Attention Deficits
Focus the attention of users. Use visual cues to highlight important points or sections of the content. If possible, eliminate 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 users attention.
Accommodating Reading, Linguistic, and Verbal Comprehension Deficits
Supplemental media such as illustrations, icons, video and audio have the potential to greatly enhance the accessibility of web content for people with cognitive disabilities. The problem is that high quality media is often difficult to produce. Poor quality media may actually decrease the accessibility of web content, by making it more confusing. But don't use this as an excuse not to try. Use your judgment. Incorporate media where it makes sense. Realize, too, that the vast majority of web content could benefit from some sort of supplemental media, if only supplemental graphics.
Document organization and structure
As a general statement, the more structured your document is, the easier it will be to understand. Structure in documents can be created by adding:
- bulleted lists
- numbered lists
- definition lists
- indented quotes (using the
All of the above structural elements can be added into the markup of the document. In other words, there are built in methods in HTML of designating a part of your content as a heading, or a list item, etc.
You can also add visual structure to a document that will benefit those who have sight. For example, you can:
- indent sub-items in a hierarchical list*
- highlight items by changing the font color or background color
Developers should not ignore the semantics of the markup language when trying to achieve a visual effect. For example, despite the fact that the
<blockquote> element causes the text within it to be visually indented, this tag should not be used for its visual effect alone. If the text truly is a quote, then the
<blockquote> element is appropriate. If the text is not a quote, then CSS (Cascading Style Sheet) attributes should be used to achieve the effect (for example, the developer could add the following style attribute to the paragraph:
It is usually easier to read text when it is visually separated from the borders of the surrounding design. People with reading disorders, such as dyslexia, can benefit from white space in the margins and vertical white 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 easier to understand than long, complex, ambiguous ones. People with more profound cognitive disabilities need sentences that are extremely short, simple, and unambiguous. 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 certainly a good idea. If, however, your primary audience is individuals with more severe cognitive disabilities you may need to create an image-only site.
To the extent possible, 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. (See also the article on writing clearly and simply.)
Accommodating Math Comprehension Deficits
Math computations or formulas can be difficult for many people to understand, whether they have a genuine deficit in math comprehension abilities or just "math phobia," to use the term "phobia" loosely. In this context, math phobia is not a clinical condition but a simple dislike of math, influenced largely by cultural factors. The United States, for some reason, has created a culture in which math is commonly disliked and derided. By way of comparison, math abilities are highly prized in Asian countries, and it would be somewhat of an insult to say that an Asian person is not good at math.
No matter what the cause of math comprehension deficits—biologically-based deficits or culturally-based aversions—authors can increase the understandability of their content by either avoiding math altogether, or by explaining the math conceptually. Where computations are required—as in e-commerce sites that add the price of the items purchased, tax, shipping and handling, and other charges—it is usually best to perform these computations automatically, so the user does not have to.
Accommodating Visual Comprehension Deficits
Usually, the best advice to help users with cognitive disabilities is to provide information in muliple formats, with a heavy emphasis on visual formats. While this remains true for the majority of people with cognitive disabilities, some types of cognitive disabilities cause difficulties in visual comprehension. If authors rely entirely on visual communication methods, some users will not understand the message. Visual communication methods include color, spatial relationships, styles, design elements, photos, images, etc.
Even though most web content suffers for a lack of visually-enhanced communicative methods, the take-home message is that no one method is sufficient by itself. Supplement the information with multiple modes and methods of communication.