Which factor primarily dictates the behavior of individuals within a group?

The behavior of individuals within a group is primarily dictated by the attitudes of its members because attitudes encompass beliefs, feelings, and predispositions to act in certain ways. They significantly influence interpersonal interactions, how individuals perceive each other, and the overall dynamics of the group. When group members share similar attitudes, it often leads to increased cohesion and collaboration, as they are more likely to support each other and work towards common goals.

In contrast, while the size of the group can affect dynamics such as communication and organization, it does not directly dictate individual behavior as strongly as attitudes do. The physical location can influence comfort and interaction levels but does not fundamentally change how individuals behave in social contexts. Age differences might shape perspectives and interactions, but it's primarily the attitudes that define how those differences will manifest in group behavior and cooperation.