WCAG SC 2.3.1 Three Flashes or Below Threshold requires that web pages do not contain any content that flashes more than three times in any one-second period unless the flash is below the general flash and red flash thresholds or if, at a typical viewing distance, on the screen, flashes occurring together don't take up more than 25% of any 10-degree area. This means they occupy no more than a total of 0.006 steradians.
To prevent content from flashing more than three times per second to avoid triggering seizures in users with photosensitive epilepsy.
Avoid flashing content: Avoid flashing content completely if possible.
Limit flashing content to three times per second: Ensure that any flashing content does not flash more than three times per second.
Use PEAT to confirm safety of flashing content: If using flashing content, use the PEAT (Photosensitive Epilepsy Analysis Tool) to confirm whether the flashing content meets the criterion.
Redesign flashing elements: Redesign flashing elements to achieve the same effect using non-flashing techniques.
Example: On an e-commerce website, a flashing banner catches the attention of visitors to indicate a limited-time discount or special offer.
The score indicator flashes rapidly whenever points are scored, exceeding three flashes per second.
Explanation:Rapid flashing in the score indicator can trigger seizures in users with photosensitive epilepsy, making the content unsafe and non-compliant with WCAG SC 2.3.1.
The web author used PEAT to determine which pulse level meets the success criterion. As a result, the banner uses a gradual color change or a brief, slow pulse that does not exceed three flashes per second.
Explanation:By using gradual visual effects instead of rapid flashing, the content adheres to the success criterion, providing a safe and accessible experience for users with photosensitive epilepsy. Use tools like PEAT to verify that the visual effects meet the necessary thresholds and make adjustments if necessary.