Investors have too often extrapolated from recent experience. In the 1950s, who but the most rampant optimist would have dreamt that over the next fifty years the real return on equities would be 9% per year? Yet this is what happened in the U.S. stock market. The optimists triumphed. However,...

Chapter 1 investigates how people's beliefs and investment behavior change in light of social information from their peers and from experts with a large-scale online experiment with participants from the U.S. and the U.K. I find that laypeople’s forecasts are strongly influenced by information...