I used to think this, until I read more about advertising and how it's designed to trigger an emotional response. More and more, I think it's really emotions that motivate most behavior. There are many people, when asked "Why did you make that decision?", will respond with some variant of "I don't know, I just felt like it."

It implies to me that most people don't really know what they feel, or why they feel that way. The corrolary to that, which I find fascinating (and a bit sad), is that it means most people really have no understanding of why they do what they do. This as true of actions as trivial as picking a brand of gum or selecting a parking spot, to choices as monumental as deciding to get married or have children.