Many decisions are interactive; the outcome of one party depends not only on its decisions or on acts of nature but also on the decisions of others. In the present article, we review the literature on decision making made by groups of the past 25 years. Researchers have compared the strategic behavior of groups and individuals in many games: prisoner's dilemma, dictator, ultimatum, trust, centipede and principal-agent games, among others. Our review suggests that results are quite consistent in revealing that groups behave closer to the game-theoretical assumption of rationality and selfishness than individuals. We conclude by discussing future research avenues in this area. JEL-Code: C910, C920.

Two experiments compared the Centipede game played either by 2 individuals or by 2 (3-person) groups. The 2 competitors alternate in deciding whether to take the larger portion of an increasing (or constant) pile of money, and as soon as one ''takes'' the game ends. Assuming that both sides are concerned only with maximizing their own payoffs (and that this is common knowledge), the game theoretic solution, derived by backward induction, is for the first mover to exit the game at the first decision node. Both experiments found that although neither individuals nor groups fully complied with this solution, groups did exit the game significantly earlier than individuals. The study of experimental games has uncovered many instances in which individuals deviate systematically from the game theoretic solution. This study is in accord with other recent experiments in suggesting that game theory may provide a better description of group behavior.

Most models of visual word recognition in alphabetic orthographies assume that words are lexically organized according to orthographic similarity. Support for this is provided by form-priming experiments that demonstrate robust facilitation when primes and targets share similar sequences of letters. The authors examined form-orthographic priming effects in Hebrew, Arabic, and English. Hebrew and Arabic have an alphabetic writing system but a Semitic morphological structure. Hebrew morphemic units are composed of noncontiguous phonemic (and letter) sequences in a given word. Results demonstrate that form-priming effects in Hebrew or Arabic are unreliable, whereas morphological priming effects with minimal letter overlap are robust. Hebrew bilingual subjects, by contrast, showed robust form-priming effects with English material, suggesting that Semitic words are lexically organized by morphological rather than orthographic principles. The authors conclude that morphology can constrain lexical organization even in alphabetic orthographies and that visual processing of words is first determined by morphological characteristics.

We examined the effects of two emotions, fear and anger, on risk-taking behavior in two types of tasks: Those in which uncertainty is generated by a randomizing device (''lottery risk'') and those in which it is generated by the uncertain behavior of another person (''person-based risk''). Participants first completed a writing task to induce fear or anger. They then made choices either between lotteries (Experiment 1) or between actions in risky two-person decisions (Experiments 2 and 3). The experiments involved substantial real-money payoffs. Replicating earlier studies (which used hypothetical rewards), Experiment 1 showed that fearful participants were more risk-averse than angry participants in lottery-risk tasks. However-the key result of this study-fearful participants were substantially less risk-averse than angry participants in a two-person task involving person-based risk (Experiment 2). Experiment 3 offered options and payoffs identical to those of Experiment 2 but with lottery-type risk. Risk-taking returned to the pattern of Experiment 1. The impact of incidental emotions on risk-taking appears to be contingent on the class of uncertainty involved. For lottery risk, fear increased the frequency of risk-averse choices and anger reduced it. The reverse pattern was found when uncertainty in the decision was person-based. Further, the effect was specifically on differences in willingness to take risks rather than on differences in judgments of how much risk was present. The impact of different emotions on risk-taking or riskavoiding behavior is thus contingent on the type, as well as the degree, of uncertainty the decision maker faces.

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