ENDOGENOUS MOVE STRUCTURE AND VOLUNTARY PROVISION OF PUBLIC GOODS: THEORY AND EXPERIMENT

In this paper we examine voluntary contributions to a public good, embedding Varian (1994)’s voluntary contribution game in extended games that allow players to choose the timing of their contributions. We show that predicted outcomes are sensitive to the structure of the extended game, and also to the extent to which players care about payoff inequalities. We then report a laboratory experiment based on these extended games. We find that behavior is similar in the two extended games: subjects avoid the detrimental move order of Varian’s model, where a person with a high value of the public good commits to a low contribution, and instead players tend to delay contributions. These results suggest that commitment opportunities may be less damaging to public good provision than previously thought.Public Goods, Voluntary Contributions, Sequential Contributions, Endogenous Timing, Action Commitment, Observable Delay, Experiment

Bypassing the energy-time uncertainty in time-resolved photoemission

The energy-time uncertainty is an intrinsic limit for time-resolved experiments imposing a tradeoff between the duration of the light pulses used in experiments and their frequency content. In standard time-resolved photoemission, this limitation maps directly onto a tradeoff between the time resolution of the experiment and the energy resolution that can be achieved on the electronic spectral function. Here we propose a protocol to disentangle the energy and time resolutions in photoemission. We demonstrate that dynamical information on all time scales can be retrieved from time-resolved photoemission experiments using suitably shaped light pulses of quantum or classical nature. As a paradigmatic example, we study the dynamical buildup of the Kondo peak, a narrow feature in the electronic response function arising from the screening of a magnetic impurity by the conduction electrons. After a quench, the electronic screening builds up on timescales shorter than the inverse width of the Kondo peak and we demonstrate that the proposed experimental scheme could be used to measure the intrinsic time scales of such electronic screening. The proposed approach provides an experimental framework to access the nonequilibrium response of collective electronic properties beyond the spectral uncertainty limit and will enable the direct measurement of phenomena such as excited Higgs modes and, possibly, the retarded interactions in superconducting systems.Comment: Extended introduction, added references to section IIB, improved wording in section II

Peer Effects in Pro-Social Behavior: Social Norms or Social Preferences?

We compare social preference and social norm based explanations for peer effects in a three-person gift-exchange game experiment. In the experiment a principal pays a wage to each of two agents, who then make effort choices sequentially. In our baseline treatment we observe that the second agent's effort is influenced by the effort choice of the first agent, even though there are no material spillovers between agents. This peer effect is predicted by a model of distributional social preferences (Fehr-Schmidt, 1999). As we show from a norms-elicitation experiment, it is also consistent with social norms compliance. A conditional logit investigation of the explanatory power of payoff inequality and elicited norms finds that the second agent's effort can be best explained by the social preferences model. In further treatments with modified games we find that the presence/strength of peer effects changes as predicted by the social preferences model. As with the baseline treatment, a conditional logit analysis favors an explanation based on social preferences, rather than social norms following for these treatments. Our results suggest that, in our context, the social preferences model provides a parsimonious explanation for the observed peer effect.peer effects, social influence, gift-exchange, experiment, social preferences, inequity aversion, measuring social norms

The Impact of Social Comparisons on Reciprocity

We investigate the effects of pay comparison information (i.e. information about what co-workers earn) and effort comparison information (information about how co-workers perform) in experimental firms composed of one employer and two employees. Exposure to pay comparison information in isolation from effort comparison information does not appear to affect reciprocity toward employers: in this case own wage is a powerful determinant of own effort, but co-worker wages have no effect. By contrast, we find that exposure to both pieces of social information systematically influences employees’ reciprocity. A generous wage offer is virtually ineffective if an employee is matched with a lazy co-worker who is also paid generously: in such circumstances the employee tends to expend low effort irrespective of her own wage. Reciprocity is more pronounced when the co-worker is hard-working, as effort is strongly and positively related to own wage in this case. Reciprocity is also pronounced when the employer pays unequal wages to the employees: in this case the co-worker’s effort decision is disregarded and effort decisions are again strongly and positively related to own wage. On average exposure to social information weakens reciprocity, though we find substantial heterogeneity in responses across individuals, and find that sometimes social information has beneficial effects. We suggest that group composition may be an important tool for harnessing the positive effects of social comparison processes.reciprocity, gift-exchange, social information, social comparisons, pay comparisons, peer effects

Sequential versus Simultaneous Contributions to Public Goods: Experimental Evidence

We report an experiment comparing sequential and simultaneous contributions to a public good in a quasi-linear two-person setting (Varian, Journal of Public Economics, 1994). Our findings support the theoretical argument that sequential contributions result in lower overall provision than simultaneous contributions. However, the distribution of contributions is not as predicted: late contributors are sometimes willing to punish early low contributors by contributing less than their best response. This induces early contributors to contribute more than they otherwise would. A consequence of this is that we fail to observe a predicted first mover advantage.public goods, voluntary contributions, sequential moves, experiment

Who Makes a Good Leader? Social Preferences and Leading-by-Example

We examine the effects of social preferences and beliefs about the social preferences of others in a simple leader-follower voluntary contributions game. We find that groups perform best when led by those who are reciprocally oriented. Part of the effect can be explained by a false consensus effect: selfish players tend to think it more likely that they are matched with another selfish player and reciprocators tend to think it more likely that they are matched with another reciprocator. Thus, reciprocators contribute more as leaders partly because they are more optimistic than selfish players about the reciprocal responses of followers. However, even after controlling for beliefs we find that reciprocally-oriented leaders contribute more than selfish leaders. Thus, we conclude that differing leader contributions by differing types of leader must in large part reflect social motivations.reciprocity, contribution preferences, leadership, leading-by-example, false consensus effect

Promoting cooperation: the distribution of reward and punishment power

Recent work in experimental economics on the effectiveness of rewards and punishments for promoting cooperation mainly examines decentralized incentive systems where all group members can reward and/or punish one another. Many self-organizing groups and societies, however, concentrate the power to reward or punish in the hands of a subset of group members (‘central monitors’). We review the literature on the relative merits of punishment and rewards when the distribution of incentive power is diffused across group members, as in most of the extant literature, and compare this with more recent work and new evidence showing how concentrating reward/punishment power in one group member affects cooperation