Why color?

What ecological advantages do animals gain by being able to detect, extract and exploit wavelength information in their environment? And what are the advantages of representing that information in the form of hue qualities? The benefits of adding chromatic to achromatic vision are perhaps marginal when it comes to object detection, but become more apparent in tasks involving object recognition and in receiving biological signals. It is argued that this impioved performance is a direct consequence of the fact that the visual system reduces wavelength information to combinations of four basic hues. This engenders a simple categorical scheme that permits a rich amount of sensory information to be rapidly and efficiently employed by cognitive machinery of limited capacity.