The hypothesis investigated was that a brief period of competition for food during infancy results in persistence in this pattern of competition for food at later stages of development in the face of the absence of hunger. 'Hungry infant mice were trained to compete over food for a few days shortly after weaning. Following this experience they were allowed to grow into adulthood without having to compete. This experience of competition during infancy turned out to cause them to fight over food on a retest many weeks later when they were sexually mature; they were not hungry at this time. The litter mates of the experimental mice were raised without competitive experience during infancy. This control group did not compete for food when adult and not hungry.' In discussing these results, Fredericson focuses upon theories of personality which emphasize the importance of early infantile experience for adult behavior patterns.