Considerations

Visual impairments

• Colour: Ensure there is sufficient contrast between textual elements, and background colours or images.
• Colour: Ensure users can see the page even if they have colour deficits, or view it on a black and white screen. If the colour contrast for any colour combination is not significant enough, users with colour deficiencies will have problems seeing the content. It is helpful to determine compliance by using an color blindness tool to simulate what the page looks like for users with certain colour deficiencies.
  • Individuals classified as totally (uncommon) or partially colour deficit (more common) can have colour vision deficiencies that are either acquired or inherited.
  • The difficulty in distinguishing colours is usually between red and green, or between blue and yellow.
• Forms: Do not use forms without submit buttons (e.g. an automated JavaScript solution). Users need the ability to control when to activate the form submission. Performing this action automatically is especially confusing for screen readers.
• Forms: Do not use radio buttons, as users with low vision have difficulty determining when a radio button is selected. Additionally, radio buttons introduce multiple form controls into the tab order. This results in extra effort for screen reader users to navigate a form.
• Headings: Screen readers allow users to jump from heading to heading, as well as navigate between different levels of heading elements. Web pages that are properly structured with <h1> to <h6> headings are much easier to navigate by screen readers.
• Images: According to the Adaptive Technology Program, alt text used in non-decorative images should help to convey the mood or experience of the site to screen reader users.
• Keyboard and UI controls: Screen readers typically work exclusively with the keyboard. While most screen readers are compatible with a mouse, users with visual impairments are unable to use the pointing functionality of a mouse.
• Links: Screen readers can extract all of the links on a web page. It is important that links are descriptive, clear, and unique so that they can stand apart from any other context and they are descriptive enough when compared to all the other links on the page.
• Quotations: The use of language attributes in the source code tell screen readers to say those words with the proper pronunciation.
• Tables: Code tables properly to ensure that screen readers can navigate through the header and data cells.

Cognitive Impairments

• Forms: Formulate questions so that the options are as short as possible. Users can get overwhelmed if they have to choose between several options with large amounts of text.
• Headings: Separate information so it is logically ordered, organized, and consistent. A properly formatted document gives users quick access, and a thorough understanding. This enhances everyone's user experience, not just those with cognitive impairments.
• Images: Include supporting images, where possible, in order to accommodate visual comprehension deficits. For example, a Web page that outlines a specific mainframe screen must be textually described for visually impaired users. The addition of screen shot images adds value for users with visual comprehension deficits, like dyslexia. Furthermore, the combination of text and imagery adds value to all users, as some people are textual learners and others are visual learners.
• Tables: Keep tables as simple as possible. Unnecessarily complex tables are hard to understand for users who have attention deficit disorder (ADD), dyslexia (difficulty reading), dyscalculia (difficulty with math), and learning disabilities in general.

Mobility, Dexterity and Coordination Impairments

• Forms: Do not use radio buttons. Users with mobility impairments have difficulties selecting them because of the small target area.
• Images: If the image is selectable (for example, a thumbnail), make sure the size of the image is large enough to accommodate users with dexterity issues.
• Keyboard and UI controls: Most assistive technologies that are used by users with mobility, dexterity and coordination impairments interface work exclusively with the keyboard.
• Links: Ensure the hyperlinked area is large enough to accommodate users with dexterity issues.
• Links: Ensure keyboard users who are tabbing between links get a visual queue when they are on a link target.
• Tables: Keep tables simple, and where possible, break them out into separate tables. If a table is long and requires vertical scrolling, then the header row may no longer be visible when viewing information further down the table. Therefore, users mobility impairments have to navigate back up to the top header, and then back down again to the content, in order to cross-reference rows with columns.