I can't find the source right now, but I read that the fastest cells in the visual pathway can respond at a bit under 500Hz. Part of the reason the ieee suggest

I can't find the source right now, but I read that the fastest cells in the visual pathway can respond at a bit under 500Hz. Part of the reason the ieee suggests a minimum PWM frequency of 3000Hz is, for signal processing reasons I don't fully understand, that's the highest frequency the brain could likely detect, given 500Hz "sampling hardware."