Final answer:
The Robbers Cave study found that competition increased prejudice between groups, neutral contact did not significantly reduce it, but cooperation on shared goals reduced the prejudice effectively.
Step-by-step explanation:
The correct description of changes in prejudice among groups in the Robbers Cave study is that groups developed prejudice when competing and that prejudice was not as successfully mitigated by neutral contact, whereas cooperating on shared goals significantly reduced the prejudice.
The Robbers Cave study, conducted by Sherif et al. (1961), is a classic example of how intergroup conflict can lead to prejudice, and how collaborative efforts toward superordinate goals can mitigate such prejudice. During the study, two groups of boys at a summer camp developed animosity while in competition, showing that prejudicial attitudes flourish under such circumstances.
Neutral contact, simply putting the two groups together without direct competition, did not significantly alleviate these attitudes, suggesting the mere presence of other groups is not enough to overcome established prejudices. However, when the two groups were given shared goals that required cooperation, there was a marked decrease in prejudice. This supports the idea that a focus on common objectives, especially cooperative tasks, can lead to greater harmony and understanding between disparate groups. These findings underscore the importance of shared objectives and active cooperation in reducing intergroup prejudices, aligning with other research like the jigsaw classroom by Aronson and Bridgeman.