This book presents investment simulations conducted with university students, MBA students, executives of the financial segment and physicians, demonstrating that investment decision making suffers behavioral biases, identified by the theories of Behavioral Finance, initiated with the Prospect Theory developed by Kahneman and Tversky (1979). The effects were tested and identified through an investment simulator on the Internet: 1) donation, which causes participants not to sell assets received, even if there are better investment options; 2) disposition, which causes the sale of winning assets very early and postpones the sale of losing assets; 3) fear of regret, which makes the participant buy assets that he stopped buying in the past and performed well and 4) approach, which depending on the perspective given to the problem, modifies the investment decision.