Take a roomful of subjects and divide them into two groups.Ask one group to choose between these two alternatives: a sure gain of $500 and a 50% chance of gaining $1,000.

• 把一群人分成两组，要求其中一组人员来做以下的选择：确定可获利500元，或有一半的机率可以获得1000元（另一半机率为获得0元）；