Abstract
What ecological advantages do animals gain by being able to detect, extract and exploit wavelength information? What are the advantages of representing that information as hue qualities? The benefits of adding chromatic to achromatic vision, marginal in object detection, become apparent in object recognition and receiving biological signals. It is argued that this improved performance is a direct consequence of the fact that many animals' visual systems reduce 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