Final answer:
The Robber's Cave study by Sherif et al. showed that cooperation can reduce intergroup conflict, indicating that common goals that require group collaboration can decrease prejudicial attitudes among conflicting groups.
Step-by-step explanation:
The classic Robber's Cave study by Sherif and Sherif (1967) demonstrated that cooperation can reduce intergroup conflict. This study involved two groups of boys at a summer camp who were initially pitted against each other, leading to increased rivalry and negative perceptions.
However, when the groups were given common goals that required cooperation, these negative attitudes were significantly reduced. The correct answer to the question is a) It demonstrated that cooperation can reduce intergroup conflict.
Earlier works by Sherif et al. in 1961 reinforced the understanding that cooperative tasks, referred to as superordinate goals, help in decreasing prejudice among opposing groups. This notion remains a cornerstone in the study of intergroup relations and conflict resolution. Additionally, employing strategies such as cooperative learning—in cases like the jigsaw classroom—has been shown to decrease prejudice through close collaboration among diverse individuals for a shared objective.