Why do people in bad moods so often act in self-destructive ways? Because a foul mood impairs our ability to assess risks, contends psychologist Roy Baumeister, Ph.D., of Case Western Reserve University. Baumeister put 48 male college students in either a good, bad, or neutral mood and offered them a chance to play one of two lotteries. In the first game the chances of winning were excellent but the payoff was small; the second offered a bigger jackpot but such long odds that most rational People would shun it (especially since losers had to listen to a recording of fingernails scratching a blackboard). Participants who were anxious or annoyed, Baumeister found, were far more likely to place the riskier bet than were those who felt good, suggesting that bad moods interfere with rational decision making. The good news? Even those in a bad mood preferred the more sensible lottery if instructed to weigh the pros and cons of each option before coming to a decision. So folks who are feeling foul night be especially wise to think before they act.