No content may flash more than 3 times per any 1-second period.
| WCAG 2 criterion | 2.3.1 Three Flashes or Below Threshold (A) |
|---|---|
| Category | Motion |
WCAG 2 criterion
2.3.1 Three Flashes or Below Threshold (Level A)
Tools and requirements
- Manual Assessment
Test procedure
If there is any content on the page that flashes or strobes more than 3 times on a page (see the "Below Threshold" provision below for more details), mark a failure. There is no provision for pausable content for this criterion.
This applies primarily to multimedia content.
"Below Threshold" provision
The flashing according to WCAG 2 is permissible if the flashing is below a certain threshold, defined by a mathematical equation. For our purposes at Cornell, we simply flag any content that contains tons of flashing of any kind greater than 3 times per second a failure.