In 2001, Fischbacher, Gächter, and Fehr conducted an experiment to study conditional cooperation in public goods games. They used a variant of the strategy method to elicit participants' willingness to contribute to a public good based on others' contributions. The study found that about 50% of participants were conditional cooperators, meaning they contributed more when others contributed more. A third were free riders, contributing little or nothing regardless of others' contributions. About 14% had hump-shaped contribution patterns, contributing more initially but decreasing later. The remaining 11.9% showed conditional cooperation but mostly below the diagonal line, indicating they contributed less than others on average. The study suggests that observed declines in cooperation in repeated public goods games may be due to self-serving biases in conditional cooperation. The experiment involved 44 participants, with each group of four making two types of decisions: unconditional contributions and contribution tables. The results highlight the importance of conditional cooperation and the role of fairness preferences in public goods experiments. The study contributes to understanding human behavior in economic settings and the factors influencing cooperation.In 2001, Fischbacher, Gächter, and Fehr conducted an experiment to study conditional cooperation in public goods games. They used a variant of the strategy method to elicit participants' willingness to contribute to a public good based on others' contributions. The study found that about 50% of participants were conditional cooperators, meaning they contributed more when others contributed more. A third were free riders, contributing little or nothing regardless of others' contributions. About 14% had hump-shaped contribution patterns, contributing more initially but decreasing later. The remaining 11.9% showed conditional cooperation but mostly below the diagonal line, indicating they contributed less than others on average. The study suggests that observed declines in cooperation in repeated public goods games may be due to self-serving biases in conditional cooperation. The experiment involved 44 participants, with each group of four making two types of decisions: unconditional contributions and contribution tables. The results highlight the importance of conditional cooperation and the role of fairness preferences in public goods experiments. The study contributes to understanding human behavior in economic settings and the factors influencing cooperation.