Under daylight conditions, most humans experience a richly colorful world in which objects appear to maintain consistent color appearances—such as green grass or blue sky. That familiar association makes it natural to believe that color is an inherent property of objects and lights. Although at first glance this idea seems reasonable, it is wrong. Color is actually a feature of our experience that is constructed from the overall pattern of illumination reaching the eye at any moment as subsequently analyzed and conditioned by the particular details of the organization of the eye and the visual system. Eyes and visual systems show great variation across the animal kingdom, so it is hardly surprising that other animals may experience color in ways that are strikingly different from ...