WCAG 1.3.3 Sensory Characteristics

Success criterion 1.3.3 makes sure that people can follow instructions even if they cannot see the shape, colour, size or position of something, or cannot hear a sound. That includes screen reader users, people with colour vision deficiency and people using a zoomed or reflowed layout where "on the right" is no longer on the right. It is level A and part of EN 301 549 (clause 9.1.3.3).

What the criterion requires

Instructions for understanding and operating content must not rely solely on sensory characteristics of components, such as:

• shape ("press the round button");
• colour ("fields in red are required");
• size ("click the big button");
• visual location or orientation ("use the menu on the left");
• sound ("continue when you hear the beep").

The instruction can mention these characteristics, but it must also give something that does not depend on a sense — usually the visible name or label of the element.

WCAG notes that the full requirements for colour are in Guideline 1.4.

Typical failures on an online shop

• "Click the green button to complete your order";
• "Use the arrows on the right to see more products" on a carousel;
• "Required fields are marked in red" with no other indication;
• "Tap the icon at the top to open your cart" when the icon has no name;
• a sound plays to confirm something, with no text message.

How to check it

Automated: no automated rule in our checker maps to this criterion. Finding instructions that rely on shape or position means reading and understanding the text. This needs a manual check.

By hand: search your templates, checkout, forms, help pages and error messages for words such as "left", "right", "above", "below", "round", "square", "green", "red", "big", "icon" and "hear". For each match, check that the element is also identified by its name or label.

How to fix it

• Name the element: "Select Place order" instead of "click the green button".
• Combine cues: "Required fields are marked with an asterisk (*) and the word required".
• Give icon buttons a text label or accessible name and use that name in instructions.
• Pair sounds with a visible text message.

Related criteria

• 1.4.1 Use of Color — colour as the only visual cue.
• 1.3.1 Info and Relationships — structure and labels in code.
• 1.3.2 Meaningful Sequence — reading order.

Frequently asked questions

Can I still write "the button on the right"?

Yes, as long as the instruction also names the button, for example "Select Continue, the button on the right". The position may be extra help, but not the only way to find it.

Are "above" and "below" allowed?

In languages where "above" means earlier and "below" means later in the content, phrases like "see the links below" are fine if the content really comes in that place in the reading order and the reference is clear.

How is 1.3.3 different from 1.4.1 Use of Color?

1.3.3 is about instructions that rely only on sensory characteristics, including colour. 1.4.1 covers any use of colour as the only visual means to convey information, not just in instructions.