American Flag Illusion

For this illusion to work, you should look at the flag for about 15 seconds and then immediately look at the white space provided. The ghostly image you see in the white space is called an after image. After images are caused when the cones in your eyes grow tired and loose their sensitivity to the colours they are looking at. When this happens, you will see white light (a mixture of all colours), minus the colour your cones have become insensitive to. In this particular example, when you are look at the white background after staring at the image of the flag, the colours that you should see are the colours on the familiar American flag (red, white and blue) which are complimentary of the colours cyan, black and yellow that were used.