In Pop Psychology, Virginia Postrel makes the case that asset bubbles are a part of the human condition that regulation can’t cure:
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, repeating the same experiment with different small groups to get a larger picture.
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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. Besides, Noussair emphasizes, “you don’t just get random noise. You get bubbles and crashes.” Ninety percent of the time.
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In an experimental market, where the value of the security is clearly specified, “worth” shouldn’t vary with taste, cash needs, or risk calculations. 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. It doesn’t matter that we know the security is worth $3.12. For the price to track the fundamental value, says Noussair, “everybody has to know that everybody knows that everybody is rational.” That’s rarely the case. Rather, “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.
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But people do learn. By the third time the same group goes through a 15-round market, the bubble usually disappears. Everybody knows what the security is worth and realizes that everybody else knows the same thing. Or at least that’s what economists assumed was happening. But work that Noussair and his co-authors published in the December 2007 American Economic Review suggests that traders don’t reason that way.In this version of the experiment, participants took part in the 15-round market four times in a row. Before each session, the researchers asked the traders what they thought would happen to prices. The first time, participants didn’t expect a bubble, but in later markets they did. With each successive session, however, they predicted that the bubble would peak later and reach a higher price than it actually did. Expecting the future to look like the past, they traded accordingly, selling earlier and at lower prices than in the previous session, hoping to realize a profit before the bubble burst. Those trades, of course, changed the market pattern. Prices were lower, and they peaked closer to the beginning of the session. By the fourth round, the price stuck close to the security’s fundamental value — not because traders were going for the rational price but because they were trying to avoid getting caught in a bubble.
“Prices converge toward fundamentals ahead of beliefs,” the economists conclude. Traders literally learn from experience, basing their expectations and behavior not on logical inference but on what has happened in the past. After enough rounds, markets work their way toward a stable price.