Country：Japan

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Country：Japan

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Country：Japan

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Grant amount：\4420000 （ Direct Cost: \3400000 、 Indirect Cost：\1020000 ）

This research aims at identifying a mechanism of leadership in teams. Specifically, we consider such a possibility that leadership is voluntarily taken by a team member who personally believes that effort is worth taking in his team. First, we formulated a game model of team production in which each member spends effort for his team given a judgment he personally holds about team productivity. We proved that leadership is realized in equilibrium if these judgments are independent across members, whereas it is not if they are correlated. Then, we tested this theory by conducting laboratory experiments. The result is that we observed emergence of leadership in teams in which subjects’ judgments about team productivity were stochastically independent, which coincides with the theoretical prediction. However, we also observed emergence of leadership in teams in which subjects’ judgments about team productivity were correlated, which contradicts with the theory.

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Grant amount：\1950000 （ Direct Cost: \1500000 、 Indirect Cost：\450000 ）

We investigate cooperation in teams by theoretical analysis of repeated games with imperfect public monitoring. In particular, we extend the model of repeated partnerships by Radner, Myerson and Maskin (1986, Review of economic Studies) allowing heterogeneous partners to choose and commit their sharing rule to achieve the most efficient equilibrium in the sense of maximizing the partners' total payoffs. We characterize the optimal sharing rule which supports the most efficient equilibrium payoff vector. We also consider the situation where it is not efficient for all members to work, and obtain the necessary and sufficient condition to achieve exact efficiency. Even when the condition fails, we obtain the approximate efficiency result.

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Grant amount：\4160000 （ Direct Cost: \3200000 、 Indirect Cost：\960000 ）

We conducted analysis by experiment, in an environment where self-signaling is not satisfied and it is difficult for cheep talk to work, (i) whether target setting by cheap talk has a positive influence on team production, (ii) whether signal with certain cost has a positive influence on team production.
As a result of the analysis, although the influence of simple cheap talk on team production is limited, the target setting by cheap talk has a positive influence on team production, and furthermore, certain costly signaling is also positive effect for team production.

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Grant amount：\4550000 （ Direct Cost: \3500000 、 Indirect Cost：\1050000 ）

We investigated a moral hazard problem in financial transactions. Specifically, we consider a repeated prisoner's dilemma between two players in which players can not observe the opponent's action but imperfectly observe signals depending on their actions. We compare efficiency losses in the different timings of releasing information combining with the different levels of noise of signals.
We found that the level of cooperation decreases as the timing of releasing signal becomes late. This experimental result implies that timely disclosure policy enhances efficiency in financial markets.

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Grant amount：\2210000 （ Direct Cost: \1700000 、 Indirect Cost：\510000 ）

When a group of individuals work in a team, there often arises a prisoner's dilemma, in which it is desirable for all the members of the team to make effort for the team while each member dose not find an interest to make the effort alone. It is widely experienced that such a dilemma is resolved occasionally by leadership in which a member of the team voluntarily make the effort in ahead of others. This fact is also verified in the research of experimental economics. However, it remains unexplored why such a limited leadership is observed.
We took into account the reported human nature that an individual tends to avoid his receiving less benefit than others in the team and to avoid also his receiving more benefit than others in the team. We showed by the method of game theory that an individual with a particular parameters of those aversion takes the leadership.

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Grant amount：\2080000 （ Direct Cost: \1600000 、 Indirect Cost：\480000 ）

With a game theoretic model, we studied how a probability with which a member of a team takes a leadership behavior in team production differs depending on his informational ability with which he forms his assessment of team productivity. We studied the sequential equilibrium in a team with symmetric informational abilities and in a team with asymmetric informational abilities. We found that(1) there exists a sequential equilibrium both in a symmetric ability team and in an asymmetric ability team,(2) there may exist multiple sequential equilibria both in a symmetric ability team and in an asymmetric ability team, and(3) it is not necessarily the case that a probability of taking a leadership behavior is increased when his/her informational ability is improved.

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Grant amount：\36790000 （ Direct Cost: \28300000 、 Indirect Cost：\8490000 ）

As a platform of a virtual society experiment, we built a system of social networking, and added the functions of wiki, online questionnaire, vitalization experiments and matching experiments. We obtained some theoretical results, such as, the condition under which vitalization of the SNS occurs. On the other hand, from our experimental results, we confirmed that the specific point system which we constructed is effective for vitalization of SNS, and that long-term relationship can induce cooperative action between people with short-term relationship. Moreover, by survey we investigated the connection between activity in SNS and ordinal human relationship.

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Grant amount：\690000 （ Direct Cost: \600000 、 Indirect Cost：\90000 ）

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Grant amount：\1810000 （ Direct Cost: \1600000 、 Indirect Cost：\210000 ）

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Grant amount：\1800000 （ Direct Cost: \1500000 、 Indirect Cost：\300000 ）

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