These newer Web tools are the underpinning technologies for a new class of interactive exhibit 3. This activity illustrates that colours appear to change when placed against different backgrounds. The colour graphic presented is interactive if you are running a Java aware browser. You are invited to look at the green, yellow and purple rectangles. Click and drag on the rectangles to swap them around.
Cone cells affect each other in complex ways.
While they give you good colour vision, they can fool your eye. When cones in one part of your eye see blue light, they make nearby cones less sensitive to blue. Because of this, you see a coloured spot on a blue background as less blue than it really is. If you put a purple spot on a blue background, for instance, the spot looks a little less blue than it would otherwise. Similarly, a spot on an orange background looks less orange than it would otherwise.