The study of Psychology can really help marketers understand customers. I recommend two tremendous courses available for free on iTunesU, which offers many free lectures. I have been listening to Psychology 156- Human Emotion and Psychology 160- Social Psychology at UC Berkeley, two very relevant courses to marketing. Both lectures are by Dacher Keltner , who is one of the best lecturers I have listened to. The lectures are also available at the course website. Psych 156. Psych 160.