Optical illusions are some of the most interesting images out there. I was little when I first saw this image. But now, the image is online and has been seen by millions. This particular illusion is very popular for its difficulty — the optical illusion shows two images at the same time, but very few people can see it. Millions of people struggle over these puzzling … [Read more...] about A rare few can see the double images in this postcard – can you?