Pic o’ the Day: Feb 2-10
Click on the picture and then watch the X in the middle very closely. You should start to see a green dot that rotates around the circle – this dot is an illusion; then you should see see the purple dots disappear…. but they haven’t really gone. It is an after image effect, sometimes called a ‘negative retinal afterimage’ – move your head slightly, and the dots will reappear… amazing or what?