WCAG 2.1 · Level A · Perceivable
WCAG 1.3.3 — Sensory Characteristics, explained with examples
Instructions must not rely solely on sensory characteristics like shape, color, size, position, or sound. "Click the green button" or "see the round icon to the right" excludes users who cannot perceive those characteristics.
- Number
- 1.3.3
- Level
- A
- Principle
- Perceivable
- Guideline
- 1.3 Adaptable
Why this criterion exists
"Click the green button" or "see the round icon to the right" excludes users who cannot perceive those characteristics.
If you only remember one thing: instructions must not rely solely on sensory characteristics like shape, color, size, position, or sound. Everything else on this page is detail.
Who feels it when this fails
Accessibility criteria sometimes feel abstract until you see who pays the cost when a site ignores them. Sensory Characteristics affects:
Color-blind users
Screen reader users
Users with low vision
How sites typically fail it
These are the patterns we see week after week. None are intentional — they are accidents of how teams build interfaces under deadline. Knowing the failure modes is the fastest path to writing them out of your component library.
"Click the red star" with no other identifier
"Use the icon at the top right"
How to test for it
Read instructions aloud; if they only make sense with sight, rewrite.
Automated scanners catch this criterion most of the time, but never all of the time. Manual testing with the keyboard and a screen reader closes the gap.
A code fix you can copy
Reference UI elements by name and role, not appearance.
The problem
<p>Click the round green button to continue.</p>The fix
<p>Click <strong>Continue</strong> to proceed.</p>Reference UI elements by name and role, not appearance.
Frequently asked questions
Does "click the button below" fail 1.3.3?
Borderline. "Below" is a positional characteristic — but unlike "the round green button", positional instructions can be sensible in sequential documents where below means later in the reading order. The safer fix is to name the button: "click the Subscribe button." Combined instruction ("click the Subscribe button, shown below the pricing table") is best practice.
Do error messages that say "see red fields" fail 1.3.3?
Yes. Telling users to "fix the highlighted fields" or "complete the red required fields" conveys meaning through color alone — which fails both 1.3.3 (sensory characteristics) and 1.4.1 (use of color). Error messages must identify the specific field by name or label and state the error in text.
Other Perceivable criteria
1.1.1 Non-text Content
Perceivable · Level A
1.3.1 Info and Relationships
Perceivable · Level A
1.4.3 Contrast (Minimum)
Perceivable · Level AA
1.4.11 Non-text Contrast
Perceivable · Level AA
All WCAG 2.1 criteria
Browse the full index by principle
Complete WCAG 2.1 guide
POUR principles, conformance levels, legal requirements
Find every accessibility issue on your site in 60 seconds.
Free public scan. No card. AI-generated fixes for every issue we find.