Gigerenzer, G. (2007). Gut feelings: the intelligence of the unconscious. New York: Viking.
Gerd Gigerenzer and his colleagues at the Max Planck Institute for Human Development in Berlin have published a compelling series of books about the roles of simple heuristics, the environment, and now, "Gut feelings" in decision making. (Quick, which city is larger: Berlin Germany or Waldorf Germany. You probably don't know the population of either, but there is a powerful heuristic that can help - familiarity. Berlin is a lot more familiar than Waldorf, so it is very likely that it is larger. (Berlin has 3.4 million inhabitants: Waldorf, corporate headquarters of SAP, has about 14 thousand.)
I first discovered their work in the book written together with Peter Todd called "Simple Heuristics that make us smart" (Deliberate takeoff on my book "Things that make us smart": peter Todd spent some time with my group in San Diego). Ever since, I have been a fan. This last book is written for the popular audience, so it is the most accessible of all, although the others are easy and fun to read as well. The power of simple rules of thumb in making us all appear far more smarter than we are was long neglected until 1999 when the first book in the series was published. No more: If you want to understand how normal folks cope with the complexity of the world, read the book. Learn about the role of heuristics, instincts, the environment, and how they come together into our "gut feelings" that are usually right, but not always. Knowing when is critical.