We all perceive colors slightly differently—what one person might think is red, for example, appears orange to someone else. Color association, however, is widely shared within a society: A red road sign conveys a warning, regardless of how you see the color red. 

In fashion, this instinctive response to color has become an integral part of a brand’s aesthetic considerations. Each season, new collections are presented at runway shows that appear to articulate a designer’s singular creative vision. Behind the scenes in the fashion world, however, color is a science rather than an art. It’s a phenomenon that Andy, the fledgling personal assistant played by Anne Hathaway in The Devil Wears Prada, discovers the hard way. Her apparently innocuous blue sweater actually represents—i...