The article shows that when people trust each other in general, they are more likely to work together in big groups even if they don't know everyone personally. This happens because of something called the social exchange heuristic, which makes people cooperate when they think others will too. The researchers tested this idea using data from surveys in four countries and looking at how people recycle. They found that people with more generalized trust are more willing to cooperate in big group situations, likely because of the social exchange heuristic.