In this experiment designed to trace the development of rivalry in Anglo American and rural Mexican children, rivalry (behavior intended to lower the outcomes of a peer) was measured by 4 choice conditions wherein the rivalrous alternative in all conditions was the choice that left fewer rewards (marbles) to the chooser's peer. After all choices…

Four experiments comparing behavior of children from Los Angeles, California, and Nuevo San Vicente, Baja California, Mexico, were conducted to analyze cooperative and competitive behavior of Anglo American city and Mexican rural children. Eighty children from each setting, 40 of age 7-9 and 40 of age 10-11, equally divided by sex, served as…