Accessibility Covers More Than What You Can See

When most people think about document accessibility, the image that comes to mind is a screen reader: a person who is blind navigating text through synthesized speech. That's a real and important use case — but it accounts for only one of the five disability categories that WCAG 2.1 AA explicitly addresses.

Documents that focus exclusively on making content readable by screen readers will still fail keyboard users with motor disabilities, people with color vision deficiency, users with cognitive and learning differences, and people with low vision who use magnification rather than screen readers. Each group has different requirements, and the WCAG criteria that serve one group don't automatically serve another.

Understanding the full scope helps organizations build remediation programs that actually work for the people who need them.

Motor disabilities — keyboard, switch, and voice navigation

Users with limited hand control, tremors, or upper-limb paralysis commonly navigate without a mouse. Some use keyboard only. Others use switch access devices — buttons or sensors that generate a small set of inputs (next, activate) to move through content one element at a time. Others use voice control software to interact with documents by speaking commands.

Two WCAG criteria are central here. SC 2.1.1 (Keyboard) requires that all functionality available through a pointer device also be available through keyboard navigation alone. SC 2.4.3 (Focus Order) requires that keyboard navigation follow a sequence consistent with the document's meaning and purpose.

In practice, this means PDF forms need a logical tab order — not just whatever geometric sequence the authoring tool defaults to. Interactive fields, buttons, and links need to be reachable by keyboard. And heading navigation (SC 2.4.1) must allow users to skip to specific sections of long documents without reading every line. For a switch access user working through a multi-page government form, a broken tab order isn't a minor inconvenience. It makes the form functionally unusable.

Vision — low vision and magnification

Low vision is not the same as being blind. Many people with low vision don't use screen readers — they use magnification software to enlarge text and interface elements, or they rely on high-contrast display modes. For them, the key requirements are contrast, text reflow, and consistent layout.

SC 1.4.3 (Contrast, Minimum) requires a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text. SC 1.4.4 (Resize Text) requires that text can be resized up to 200% without loss of content. These criteria are well-known, but they're often applied incompletely — contrast checks on body text that miss form field labels, decorative elements, or small-print footnotes.

For users who rely on magnification, a well-structured tag tree also matters: magnification software that can reflow text into a single readable column depends on correct tag structure to determine which text is body content and which is a header, footnote, or artifact.

Color vision deficiency

Roughly 8% of men and 0.5% of women have some form of color vision deficiency. Documents that use color as the sole means of conveying information — a red/green status indicator, a chart where categories are distinguished only by color — are inaccessible to users who can't distinguish those colors.

SC 1.4.1 (Use of Color) requires that color not be the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. This means status information needs a text label or pattern in addition to color. Charts need data labels or patterns in addition to colored fills. Maps need legends with symbols, not just color keys.

This criterion applies independently of contrast. A document can pass the contrast check (the colors are distinguishable from the white background) and still fail SC 1.4.1 (the colors aren't distinguishable from each other). Both checks are necessary.

Cognitive and learning disabilities

This is the category that receives the least attention in most accessibility audits, and arguably the one with the widest reach. Dyslexia, ADHD, traumatic brain injuries, and autism all affect how people process written information — particularly dense, unstructured, or unfamiliar content.

SC 1.3.1 (Info and Relationships) supports cognitive accessibility by requiring that structural relationships — what's a heading, what's a list, what's a label — be expressed in the document's markup, not just its visual appearance. When heading hierarchy is correct, people using text-to-speech tools for cognitive support can navigate to the section they need rather than processing the entire document linearly. When lists are properly tagged, they read clearly rather than as an undifferentiated block of text.

SC 2.4.6 (Headings and Labels) extends this by requiring that headings and labels be descriptive — not just present. A document with headings labeled "Section 1," "Section 2," "Section 3" technically has headings, but provides no navigational value to someone trying to locate specific content. Descriptive headings reduce cognitive load for all users and are essential for people who rely on document navigation to manage attention and comprehension.

Language identification (SC 3.1.1 and SC 3.1.2) is another frequently overlooked cognitive accessibility requirement. When a document's language metadata is set correctly, text-to-speech software uses the right pronunciation rules. When it isn't set — or when a document contains sections in multiple languages with no language change markers — the software reads foreign words with incorrect phonetics, which can make content difficult or impossible to follow for users relying on it for comprehension support.

Alt text and contrast are necessary but not sufficient

SC 1.1.1 (Non-text Content) and SC 1.4.3 (Contrast, Minimum) are probably the two most widely understood accessibility requirements for documents. They're genuinely important. Alt text for images and figures ensures that users who can't perceive visual content still receive the information it conveys. Sufficient contrast ensures that text is legible across a range of visual conditions.

But treating these two criteria as the definition of an accessible document leaves the majority of WCAG 2.1 AA requirements unaddressed. A document with excellent alt text and perfect contrast ratios can still fail every keyboard navigation requirement, convey information through color alone, have no meaningful heading structure, and carry incorrect language metadata. Each of those failures affects a real group of users in a specific, concrete way.

The goal of a WCAG 2.1 AA conformant document is not to check a subset of criteria — it's to ensure the document works for people across the full spectrum of disabilities. Starting with a complete picture of what that spectrum looks like is the right place to begin.