Chao Liu

Date of Award


Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Arts (MA)




Peter LaFreniere

Second Committee Member

Cynthia Erdley

Third Committee Member

Mary Logue


This study is the first to test the evolutionary hypothesis that mixed-age settings increase cooperation and reduce competition among peers. Triads of 30 preschoolers (ages 4-6) and 10 third to six graders (ages 8-13) were observed when they were involved in a game playing situation that involved limited resources, where 20 pairs of preschoolers were tested twice: once in a same-age group and once in a mixed-age group. Children in mixed-age groups were more cooperative than children in same-age groups and these cooperative behaviors were more frequently initiated by older children. Whereas children in same-age groups spent more time interfering and being unoccupied, children in the mixed-age groups spent more time playing the game, were more equitable and better organized and had more smooth turn-taking behaviors than same-age groups. These findings demonstrate the potential benefits of mixed-age interaction that are deeply rooted in our evolutionary heritage.