Animal Spirits: How Human Psychology Drives the Economy, and Why It Matters for Global Capitalism (2009) is a book written to promote the understanding of the role played by emotions in influencing economic decision making. According to the authors, economists have tended to de-emphasize the importance of emotional factors, as the effects of emotions are difficult to model and quantify. The book asserts that a variety of otherwise puzzling questions can be answered once one allows for the effect that emotional drives, or "animal spirits," have on economic factors.