The phenomenon of predating predators requires at least three specimens to whom we refer as players 1, 2, and 3. Player 1 has simply to guess nature when trying to find food. Player 2 is hunting player 1 in the hope that 1 is well fed but must also avoid being hunted by player 3. One major...

In this paper we report experimental results that relate to the recprocity experiment of Berg, Dickhaut, and McCabe (1995). We consider direct reciprocity, which means to respond in kind to another person, and indirect reciprocity, understoode as rewarding someone else. Another variation conerns...