Sherif, M. (1956). Experiments in group conflict. Scientific American, 195, 54-58.
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In this study, Sherif used an elaborate field experiment to examine group dynamics using randomly created groupings. This was carried out by bringing 11-12 year old boys to a summer camp. The boys were randomly assigned to one of two groups. During the first phase of the experiment, group members participated in challenging tasks with each other (i.e., hiking). This lead to social hierarchies being created in which clear leaders emerged.
During the second phase of the experiment, the groups had to compete against each other in various types of contests with trophies and prizes being offered to the winning group. During this phase, group cohesiveness increased while intergroup conflict and animosity strengthened.
During the third phase of the experiment, Sherif attempted to reconcile the two groups. This was accomplished by presenting them with problems in which they must all work together to solve. A specific example of this was having a truck "break down" and requiring members from both groups to push the truck. These activities served to forge bonds between members of each group.
This study is a classic in social psychology in that it demonstrated that prejudices and animosity towards members of other groups occurs when they are in competition for the same resources. This was very important on the heels of the the Holocaust, explaining how the Germans, who saw the Jews as competition for economic resources, could support the egregious acts that were inflicted on this group of people.
Levine, R. A., & Campbell, D. T. (1972). Ethnocentricism: Theories of conflict, ethnic attitudes and group behavior. New York: Wiley
Orlick, T.D. (1981). Positive socialization via cooperative games. Developmental Psychology, 17, 426-429.