The effect only occurs if the elements are small enough, so in fullscreen they are probably too large. You can step away from your screen a bit and you'll see t

The effect only occurs if the elements are small enough, so in fullscreen they are probably too large. You can step away from your screen a bit and you'll see the effect as well in fullscreen. As far as I understand, the effect is caused by the fact that the fovea has a much higher resolution (of bright light) due to its higher density of cones. At a certain size, the fovea is still able to make out details of the elements, but the rest of the retina can not. Thus they are detected as rotating in the fovea area, but not outside (since it's basically just a colored lump there. We still perceive the outside ones as stars (and not just color lumps) because the brain interpolates them that way due to previously perceived information. Under low light conditions, i.e. when rods would be the main means of vision, an opposite effect can be observed: We are mostly blind in the fovea area due to the lack of rods there. This manifests as objects showing more detail at night when looking slightly past them.