Reputation can influence how people cooperate with each other. In real life, reputations are often unclear. Researchers used online experiments to see how unclear reputations affect cooperation. They found that when reputations are low, people are less likely to trust others. Medium or high reputations don't change people's choices. Without the option to choose partners, reputation doesn't make people more cooperative. But when reputation is important for choosing partners, more people act cooperatively. This shows that unclear reputations can help identify untrustworthy individuals and encourage cooperation when selecting partners.