Another technique for tuning into the perception of horizontal motion: Use your hands or forearms to block your view of most of the picture, leaving only a narr

Another technique for tuning into the perception of horizontal motion: Use your hands or forearms to block your view of most of the picture, leaving only a narrow horizontal slit. For me the effect persists upon expanding my view to the full picture again. To 'switch back', look at a thin vertical strip of the picture for a moment. As soon as I manage to see the motion as left-to-right, the dots look yellow — though the impression is really close to flickering between red and green. How readily your visual system will merge individual strobes into a coherent, moving visual impression depends a lot on how awake/alert you are at the moment. So you could also try again when you're more tired. Another thing to try: Change the playback speed to 2x. Though I'm not sure if that will increase the frame rate to 60Hz or skip frames. In this case you want the former; it may be necessary to download the video and play it back locally to achieve that. By the way, I once managed to produce a similar illusion completely by accident: I had made an engine for rendering totalistic 2D cellular automata (a superset of Conway's Game of Life) that randomised the state-transition rules upon a keypress. After a while of browsing random rules, I found one with a tendency to produce neat tiny gliders: A sequence of three distinct colours (and therefore states, I thought) racing across the screen — something like a cyan dot trailing a purple one behind it, with a pink one sandwiched between them. But then I looked closer and saw that the pattern was only two cells wide. Taking a screen-shot and looking at the freeze-frame confirmed that the gliders only occupied two neighboring cells, with two different colours, at any given point in time.