How do human beings decide when to be selfish or selfless? In this study, we gave testosterone to 25 men to establish its impact on prosocial behaviors in a double-blind within-subjects design. We also confirmed participants' testosterone levels before and after treatment through blood draws. Using the Ultimatum Game from behavioral economics, we find that men with artificially raised T, compared to themselves on placebo, were 27% less generous towards strangers with money they controlled (95% CI placebo: (1.70, 2.72); 95% CI T: (.98, 2.30)). This effect scales with a man's level of total-, free-, and dihydro-testosterone (DHT). Men in the lowest decile of DHT were 560% more generous than men in the highest decile of DHT. We also found that men with elevated testosterone were more likely to use their own money punish those who were ungenerous toward them. Our results continue to hold after controlling for altruism. We conclude that elevated testosterone causes men to behave antisocially.

Purpose -The purpose of this paper is to examine empirical characteristics of two commonly mentioned expressions of international financial crisis, "sudden stops" and currency crises. Design/methodology/approach -Sudden stop and currency crisis events are identified and empirical regularities among them are analyzed based on the annual data of 25 emerging market countries from 1990 to 2003. Findings -Puzzlingly, these two seemingly close expressions of crises overlap less than 50 percent of the time and sudden stops more frequently precede than follow currency crises. Also the two different sudden stop measures are not strongly correlated with each other. Research limitations/implications -This shows that it can make a great deal of difference what measure is used and suggests that studies in this area should be sure to check the robustness of their results to different measures. Practical implications -The authors think that the proper analysis should focus on how to use these different measures to understand the nature of the crises. Thus, sudden stop and currency crisis measures should be used as complements, rather than substitutes. Social implications -The alarming frequency of the emerging market crises during the last three decades has motivated a large volume of theoretical and empirical literature on the subject. The paper's results advance understanding of these events. Originality/value -A large body of studies on currency crises coexists with a growing literature on sudden stops yet a majority of the studies that investigate either one of these phenomena do not mention the other. The paper adds value by investigating empirical relationships between them.

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