PZ seems to think there may be a genetic component to the difference in color perception in western people and the Himba tribe but I'm skeptical. The time since there has been any real genetic isolation seems far too small for there to be such a difference between populations of humans. I'm struggling to come up with a better example of how learning effects perception but many optical illusions come to mind. There is a whole genre of illusions that look like nonsense at first but once you "learn" what the image is it is impossible to remember what you thought you saw before. Even the classic two faces or a vase image can work this way. I imagine that color perception could involve this same kind of "gestalt" perception.