Which term is used to describe the collective effort of group members leading to decreased individual performance?

The term that accurately describes the phenomenon where the collective effort of group members leads to decreased individual performance is social loafing. This occurs when individuals in a group put in less effort than they would if they were working alone, often because they feel less accountable and believe their individual contributions may not be evaluated as critically. This reduction in effort is more likely in larger groups as members might think that their absence will not significantly affect the overall group outcome.

In contrast, social facilitation refers to the improved performance of individuals when they are in the presence of others, especially on simple or well-learned tasks. Groupthink is a psychological phenomenon that occurs when the desire for harmony or conformity in a group leads to irrational decision-making, while group polarization describes the tendency for group discussions to amplify the initial leanings of group members, resulting in more extreme positions than those that individual members would adopt alone.