We investigate how group boundaries, and the economic environment surrounding groups, affect altruistic cooperation and punishment behavior. Our study uses experiments conducted with 525 officers in the Swiss Army, and exploits random assignment to platoons. We find that, without competition...

We examine the strategic sophistication of adolescents, aged 10 to 17 years, in experimental normal-form games. Besides making choices, subjects have to state their first- and second-order beliefs. We find that choices are more often a best reply to beliefs if any player has a dominant strategy...