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Perceivable WCAG 1.3.3

1.3.3 Sensory Characteristics

Instructions provided for understanding and operating content do not rely solely on sensory characteristics such as shape, color, size, visual location, orientation, or sound.

Level A Moderate WCAG 2.0 (new) WCAG 2.1 WCAG 2.2

What this rule means

Success Criterion 1.3.3 requires that instructions for interacting with content do not depend exclusively on sensory perception. When you tell users to "click the round button" or "select the option on the left," you assume they can perceive shape and spatial position. Users who are blind, have low vision, or use assistive technologies may not perceive these characteristics.

Instructions must include non-sensory cues such as text labels, names, or roles. Instead of "click the green button," say "click the Submit button (green)." The sensory cue can supplement but must not be the only identifier.

Why it matters

Blind users cannot see shapes, colors, or visual locations. Users with color vision deficiency may not distinguish color-coded instructions. Deaf users cannot hear audio cues. When instructions rely solely on sensory characteristics, entire groups of users are excluded from understanding how to interact with the content.

This criterion also benefits users with cognitive disabilities who may struggle to interpret spatial references like "above" or "to the right of" in complex layouts, especially on mobile devices where visual arrangement changes.

Related axe-core rules

There are no automated axe-core rules for this criterion. Sensory instructions require manual review because automated tools cannot determine whether an instruction relies solely on sensory characteristics. Content audits and user testing are necessary.

How to test

  1. Search the page for instructions that reference shape ("round button," "square icon"), color ("red warning," "green link"), size ("large heading"), location ("sidebar," "right column"), or sound ("after the beep").
  2. For each instruction found, verify that it also includes a text-based identifier (label, name, or role).
  3. Check error messages and help text to ensure they do not say things like "the field highlighted in red" without also naming the field.
  4. Review audio or video content for instructions that rely on sound alone without text equivalents.

How to fix

Always pair sensory descriptions with text labels:

<!-- Bad: relies only on shape and position -->
<p>Click the round icon on the right to continue.</p>

<!-- Good: includes text label alongside sensory cue -->
<p>Click the "Next" button (round icon on the right) to continue.</p>

When referencing form errors, name the specific fields:

<!-- Bad: relies only on color -->
<p>Please correct the fields highlighted in red.</p>

<!-- Good: names the fields -->
<p>Please correct the following fields: Email and Phone number.</p>

For interactive elements, ensure the instruction references an accessible name:

<!-- Bad -->
<p>Use the triangle button to play the video.</p>

<!-- Good -->
<p>Click the "Play" button to start the video.</p>
<button aria-label="Play">
  <svg><!-- triangle icon --></svg>
</button>

Common mistakes

  • Error messages saying "see the red field above" without naming the specific field.
  • Instructions like "click the icon on the left" in a toolbar without identifying which icon by name.
  • Using color alone to indicate required fields (e.g., "fields marked in red are required") without a text marker or asterisk.
  • Tutorial text saying "as shown in the image below" when the image has no text description.
  • Navigation instructions like "use the menu at the top" without saying "use the Main Navigation menu."

Resources