You’ve seen the warnings before TV shows and movies. “This show contains flashing lights.” This warning on visual media also applies web sites and apps. Guideline 2.3.1 addresses this by implementing a requirement that reduces the potential for severe damage. Let’s discuss why.
Epilepsy
Epilepsy is the first thing we think of when talking about photo-sensitivity. It has been well documented over the years. Flashing lights above 55hz, or about 3 pulses in one second, can trigger seizures. Depending on the speed and the viewer, this can actually cause death.
Other Issues
Epileptics are not the only people that may be affected. People sensitive to motion, like vestibular disorders, can be affected. The flashing can induce a state of anxiety. It can induce dizziness. People with a cognitive issue also can be set off by rapidly flashing items. Most importantly, they’re a distraction that can prevent completing the task.
Conclusion
If you are using moving graphics on your site, ensure that any flashing is slower than three flashes per second. Tools like PEAT can help. However, it is geared for television. You need to record your screen in the right format.