The study looked at how people behave in a game where they can give money to others. They found that when people think the other person would also give money if roles were reversed, they are more likely to give money. This is called reciprocal altruism. However, even when people are matched with those from different backgrounds, they still show altruistic behavior. The results show that most people have conditionally altruistic preferences, meaning they give based on what they think the other person would do. Unconditional altruism, where people give without expecting anything in return, was rare in both cases. These findings have important implications for understanding how people make decisions in social situations.