When Pokémon caused all those seizures in the Japanese kids (thanks to the Porygon flashing), I saw a lot of conspiracy theories on the 'net that Nintendo was trying to put in super-secret mind-control messages into the flashing in order to cause kids to get their parents to spend lots of money on Pokémon stuff (among less serious ones, such as reprogramming them to think they're various animals or whatever). Of course, it would seem that abject consumerism was all it really needed, which is likely why the Porygon Flash hasn't been experienced by American kiddies yet - it hasn't been necessary yet.