The study looked at how people's willingness to cooperate in group settings can change based on who they are matched with. They found that when people were matched with others from their own group, they were more likely to cooperate and less likely to be selfish. However, when matched with people from a different group, they were more likely to be free riders and not cooperate as much. This suggests that feeling like you belong to a certain group can affect how you behave in group situations.