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Virginia Postrel writes:
Pop Psychology: For more than two decades, economists have been running versions of the same experiment. They take a bunch of volunteers, usually undergraduates but sometimes businesspeople or graduate students; divide them into experimental groups of roughly a dozen; give each person money and shares to trade with; and pay dividends of 24 cents at the end of each of 15 rounds, each lasting a few minutes. (Sometimes the 24 cents is a flat amount; more often there’s an equal chance of getting 0, 8, 28, or 60 cents, which averages out to 24 cents.) All participants are given the same information, but they can’t talk to one another and they interact only through their trading screens. Then the researchers watch what happens.... “The fundamental value is unambiguously defined,” says the economist Charles Noussair, a professor at Tilburg University, in the Netherlands, who has run many of these experiments. “It’s the expected value of the future dividend stream at any given time”: 15 times 24 cents, or $3.60 at the end of the first round; 14 times 24 cents, or $3.36 at the end of the second; $3.12 at the end of the third; and so on down to zero. Participants don’t even have to do the math. They can see the total expected dividends on their computer screens....
The trading price should stick close to the expected value. At least that’s what economists would have thought before Vernon Smith, who won a 2002 Nobel Prize for developing experimental economics, first ran the test in the mid-1980s. But that’s not what happens. Again and again, in experiment after experiment, the trading price runs up way above fundamental value. Then, as the 15th round nears, it crashes. The problem doesn’t seem to be that participants are bored and fooling around. The difference between a good trading performance and a bad one is about $80 for a three-hour session, enough to motivate cash-strapped students to do their best....
Experimental bubbles are particularly surprising because in laboratory markets that mimic the production of goods and services, prices rise and fall as economic theory predicts, reaching a neat equilibrium where supply meets demand. But like real-world purchasers of haircuts or refrigerators, buyers in those markets need to know only how much they themselves value the good. If the price is less than the value to you, you buy. If not, you don’t, and vice versa for sellers. Financial assets, whether in the lab or the real world, are trickier to judge: Can I flip this security to a buyer who will pay more than I think it’s worth?... Based on future dividends, you know for sure that the security’s current value is, say, $3.12. But—here’s the wrinkle—you don’t know that I’m as savvy as you are. Maybe I’m confused. Even if I’m not, you don’t know whether I know that you know it’s worth $3.12. Besides, as long as a clueless greater fool who might pay $3.50 is out there, we smart people may decide to pay $3.25 in the hope of making a profit.... Noussair... “if you put people in asset markets, the first thing they do is not try to figure out the fundamental value. They try to buy low and sell high.” That speculation creates a bubble.
In fact, the people who make the most money in these experiments aren’t the ones who stick to fundamentals. They’re the speculators who buy a lot at the beginning and sell midway through, taking advantage of “momentum traders” who jump in when the market is going up, don’t sell until it’s going down, and wind up with the least money at the end. (“I have a lot of relatives and friends who are momentum traders,” comments Noussair.) Bubbles start to pop when the momentum traders run out of money and can no longer push prices up...
