I've seen this repeated many times but never seem any evidence for it. At typical PWM frequencies the perceived brightness is just the average brightness of the

I've seen this repeated many times but never seem any evidence for it. At typical PWM frequencies the perceived brightness is just the average brightness of the wave. I believe this myth arose from people driving low-brightness indicator LEDs using PWM for increased efficiency when using simple current-limiting resistor circuits. People saw the energy savings from less waste heat in the resistor and somehow confused it with something happening in the eye.