. . . A recent experiment by Shigeru Watanabe showed that the utterly un-artistic pigeon could be taught to identify "good" and "bad" children's artwork. How was the pigeon able to perform this feat and why should we care that it did? Categorizing these patterns of visual stimulation allows you to make sense of an often complex and chaotic world. Remarkably, when pigeons are suitably trained, they too can learn a variety of visual categories. Understanding how animals categorize and process these visual stimuli has important implications for our view of both animals and people. These kinds of discriminations attest to the ability of animals to learn both categories and concepts, once thought to be uniquely human abilities. . .