Friday, 12 September 2014


If you watch the above video normally, the moving circles in the first animation rotate while the shifting dots in the second clip follow a horizontal path. But if you look away and watch the movie out of the corner of your eye, the direction of motion will appear to change. In both cases, the moving objects seem to follow the direction of the background stripes. The illusion proves that we perceive motion very differently when it's in the periphery compared with when it's picked up by the fovea, a tiny area at the back of the eye responsible for central vision. Looking at a scene directly results in the sharpest vision, whereas our peripheral vision is good at picking up motion but poor at making out the details of shapes.