One would think that once was enough to learn the lesson. The story has disappeared, and nobody worries anymore about cartoons causing problems. What set the children off was the flashing red eyes of a cartoon animal. They only flashed for about 5 seconds, yet that was enough to totally disrupt function in these children. Actually, this phenomenon has been known for more than 50 years.
Neurologists know that vulnerable people can go into seizure when exposed to flashing lights.
Apparently the brain makes its own rhythms, and more importantly, lives by them. The brain has to organize a lot of activities at the same time, and different parts of the brain have to talk to each other. That process of talking back and forth has to happen faster than anything we actually do'like defend in basketball, or catch a baseball. After all, the brain has to plan out everything we actually do ahead of time. We also know how fast the brain can track incoming messages, such as the sounds of music, so we know it has to work at least as fast as that.