Abstract
This chapter discusses the ordering of color percepts, and starts by presenting an overview of the critical issues surrounding the topic and by examining the relationship between stimuli and percepts. Certain types of variability were found by experimental psychology in the relationship between stimulus and response as a result of observation conditions. In the twentieth century, the view that the normal human color-vision system has a standard implementation and that all perceptual data are appropriately treated with normal statistical distribution methodology became the standard paradigm. However, the idea that the large number of color percepts humans can experience must fit into some kind of ordering system is an old one, going as far back to Aristotle and his proposed color categories based on a scale of chromatic colors between white and black. The strengths and limitations of the more recently developed kinds of color order systems are also touched upon here.