Decision theorists have performed experiments in which people are given various choices between sure things (amounts of money) and simple lotteries in order to see if the subjects’ preferences are rationally ordered. They find that people will generally choose a sure gain over a lottery with a higher expected gain but that they will shun a sure loss in favor of an even worse lottery (as long as the lottery gives them a chance of coming out ahead). These evidently instinctive human tendencies spell doom for the trader—take your profits, but play with your losses.
