We analyse two team settings in which one member in a team has stronger incentives to contribute than the others. If contributions constitute a sacrifice for the strong player, the other team members are more inclined to cooperate than if contributions are strictly dominant for the strong player.

Broken Windows: the metaphor has changed New York and Los Angeles. Yet it is far from undisputed whether the broken windows policy was causal for reducing crime. In a series of lab experiments we show that first impressions are indeed causal for cooperativeness in three different institutional...

Laboratory experiments by Fudenberg and Pathak (2010), and Vyrastekova, Funaki and Takeuch (2008) show that punishment is able to sustain cooperation in groups even when it is observed only in the end of the interaction sequence. Our results demonstrate that the real power of unobserved...