Just as the title says, do games or programs or any other form of motion picture play/run smoother at a framerate higher than 60fps ? Or is the the popular opinion that says the human eye can't notice any difference in framerates higher than 60fps is tactually a fact ?
Good question. No, it's not a myth and there's many aspects to this answer.
Running the monitor faster and rendering games with vsync on with no dropped frames, you get an increase in temporal resolution. Therefore, a 120Hz monitor has literally twice the timing/temporal resolution of a 60Hz one. Motion is literally twice as smooth and it
is visible. 240Hz will in turn look smoother than 120Hz, but the perceived gain will be much less due to the limits of the human visual system.
On CRT monitors, increasing the scanning rate did several things, the main ones being to noticeably reduce flicker, increase temporal resolution & motion smoothness and blur the picture (you really don't want this last one, lol).
Heck, I managed to get 144Hz at 800x600 on one of my CRTs and a static picture literally looked
stuck on the screen. Hard to really get across, but an amazing effect. I actually did this to try out 3D Vision on it, which surprisingly worked fine, since it's designed for 120Hz. Note that the static picture I'm talking about was a 2D one without the glasses.
On LCD monitors, you increase the temporal resolution and reduce the inherent and significant motion blur in LCD displays. There is no loss of sharpness though, especially with a digital connection and running at native resolution.
The eye is particularly sensitive to dropped rendering frames though (eg game animation) which reveals itself as unpleasant stutters and double images. However, if you lose a few frames at 120Hz, the effect is much less noticeable.
On perception, I saw something geekily interesting once. I once played a game through the 50Hz UK PAL TV out on my video card (non interlaced) with the monitor output set to 100Hz. This resulted in the game being rendered at 50fps/Hz as it was vsync locked to the TV. This resulted in each image being displayed twice on the monitor. Normally, if the monitor is being run at 50 or 60Hz and the game is rendered at half the framerate, this will be perceived as severe judder and a double image. However, because the monitor was running at 100Hz, it was perceived as a smoothly animated double image with no judder. Fascinating!