Another major factor in motion pictures is that each frame also contains a substancial amount of blur. This allows your mind to compensate for the lack of fram

Another major factor in motion pictures is that each frame also contains a substancial amount of blur. This allows your mind to compensate for the lack of frames. I'm not sure how projectors work, exactly, but I suspect they also fade into and out of each frame in some way. That is, it probably doesn't operate like this: show frame -> clear screen -> show next frame. LEDs and the like are usually set up to be either on or off (a square wave) causing the flicker much more apparent. Street lamps are sort of a hybrid, they "flicker" at 60hz, but their flicker is not a square wave, but rather a sine wave.