Scott says:
Seems to me that when I cover the middle, the apparent increase in dots speed is accompanied by a flattening of the 3D – the dots seem to radiate more in a plane.
When I cover the edges, the 3D effect increases: the slower dots in the middle appear to me as if I’m looking at them down a tunnel or tube.
That the dots are indeed radiating differently at different radii is necessary for the original “warp” effect. Moving rapidly through a real 3D array of random dots, I would indeed see the dots in the center appear to move more slowly. The dots near the center represent the “distant” stars; more outward, they represent the ones I’m just now flying past.
Andras says:
this is not an illusion, it’s a trick, an animated gif. the dots in the edges move faster than the ones in the middle, originally.
So no wonder that if you cover the centre, you notice that the dots in the edges mover very fast, and if you cover the dots in the edges you see that the dots in the middel mover slower.
Proof: look only in one edge, then cover the centre and notice there is no difference.
Look at the centre, cover 2 edges and notice there is no change in the middle.