Regarding an earlier mention of the need for a warning about the strobe effects in the film, the front doors of our theater had printed warnings taped to them stating that people with photosensitive epilepsy may wish to not view Incredibles 2 due to the scenes with strobe effects!
Since I often shoot indoor youth sports with mounted strobe systems and often fire multiple frames per minute, I've had to deal with people generally bothered by them stating that I shouldn't use them because "it could cause someone to have a seizure." So I've done some reading on the matter. My random firing shouldn't be a problem because people with photosensitive epilepsy require a series of steady timed flashes of light at their personal "trigger frequency". For most people it's between 5 and 30 strobes a second. In watching Incredibles tonight, I was surprised that the effects lasted as long as they did, but I think they do switch the frequency at intervals... but I'd like to see it again to be sure.
I realize that such strobe effects might give people headaches instead of seizures, but it will be interesting to see if these strobe effects become a public issue about the film.
Update: I Googled the topic and it appears that Disney has asked theaters to post the warnings after a social media post went viral by a woman claiming that they "could" trigger a long list of issues without any actual reports of it happening. She stated that a family member determined they flash frequency was "up to 3 times a second". If true, based on what I've read, that would generally considered safe for even people with photosensitive epilepsy.
Thank you for posting this information. Interestingly, the woman whose social media went viral is apparently visually impaired and heard a mention of lights on the visual description she was listening to with the movie. She then had family members watch for lights.
The ‘general’ recommendation for people who experience disorientation, dizziness or motion sickness related to light is to close their eyes since those seem to be most related to a mismatch of messages sent to the brain by the eyes (movement) and the inner ear (no or different movement).
This is an edit of information I wrote a long time ago about flashing lights on the disABILITIES FAQs thread. The same is generally true for people who get migraines from lights.
Most people think of strobe lights when they think of seizures, but most people with seizures don't have any problems with strobe lights.
Many people call any flashing light a strobe light, but true strobe lights actually flash quickly and rhythmically on a regular pattern.
Lights that are irregularly flashing are a different situation.
Most true strobe lights flash many times per second, but slowing to 5 flashes per second or less means that the majority of even photosensitive epileptics are not going to have a problem.
Only about 3-7% of people with epilepsy are photosensitive and have problems with lights; of those, only about 5% would have a problem with a light flashing 5 times per second or less.
This is something to talk to your doctor with, but in for most people with epilepsy, flashing lights are something to be aware of, but are not likely to cause a problem.
If you do encounter flashing lights and are concerned, the Epilepsy Foundation recommends covering one eye and turning/looking away from the direct source of light. The reason for covering only one eye and looking away from the direct light is to prevent both eyes from sending exactly the same information to the brain.