WCAG 2.1 Principles Explained: Perceivability

The Web Content Accessibility Guidelines (WCAG) are the most popular and well-recognized standards for evaluating the accessibility of websites and other internet content.

With the release of the latest version in June, WCAG 2.1, now is the perfect time for a refresher on the four WCAG main principles. Let’s kick off the series with the first WCAG principle: perceivability.

The Perceivability Principle

WCAG requires web content to be perceivable to users. Information and user interface components must be presented in a way that all users can recognize and understand.

One of the biggest barriers to perceivability is content that is only available in visual or in audio format. More than 7 million people in the United States have a visual disability, while more than 28 million are affected by hearing loss.

To ensure that all users can benefit from your website, your content must be easily convertible between different formats, or it must include alternatives that are functionally equivalent. For example, WCAG requires pre-recorded videos to have transcripts or closed captions so that users with hearing disabilities can perceive the audio content as equally well as users without disabilities.

Assistive technologies such as screen readers and braille displays are essential to perceivability under WCAG. Many people with disabilities interact with the Web using these technologies, and therefore rely on your website to be compatible with them.

What Developers Should Know About Perceivability

In most cases, the key to perceivability is converting non-textual content into text, which can then be processed by the assistive technology of the user’s choice.

Alternative text for non-textual content, and in particular closed captions and transcripts for audio content, should be among developers’ primary concerns for perceivability. Not only will this assist people with disabilities, it’s also beneficial for your website in terms of SEO and user engagement.

Other perceivability concerns under WCAG include the use of high-contrast color schemes and the ability to resize text, so that people with low vision can successfully use and navigate your site.

Perceivability in WCAG 2.1

WCAG 2.1, which expands on the very popular WCAG 2.0 standards, includes several new guidelines intended to improve the perceivability of website content:

• Orientation (1.3.4): Websites and applications must support both portrait and landscape modes, unless absolutely necessary. This allows users with visual disabilities to rotate their mobile devices to increase text size.
• Identify Input Purpose (1.3.5): Websites must include indications about what kind of data to enter in a field. This allows the browser to autofill some forms, and allows assistive technologies to better inform the user about the purpose of different fields.
• Identify Purpose (1.3.6): Similarly, interface components such as icons should have specific labels within the code that assistive technologies can interpret. For example, a button that returns the user to the main page should be labeled “home button.”
• Reflow (1.4.10): Websites must use responsive design so that the text can be enlarged while the layout is preserved.
• Non-Text Contrast (1.4.11): To assist users with low vision, active interface components and non-text content should have a contrast ratio of at least 3:1.
• Text Spacing (1.4.12): Users must be able to increase the spacing between lines, paragraphs ,and words without losing functionality.
• Content on Hover or Focus (1.4.13): A user should be able to be dismiss pop-up content that appears in a modal window or tooltip at will and without having to move the pointer hover or the keyboard focus.

Final Thoughts

Making your content perceivable under the WCAG recommendations ensures that all users will be able to understand and interact with your website. For more information about the four WCAG principles, follow the Bureau of Internet Accessibility blog, or contact us for a free 30-minute consultation with our internet accessibility experts.