Compare methods

	Public Goods Game	Trust Game
Field	Social Psychology	Social Psychology
Family	Process / pipeline	Process / pipeline
Year of origin	2000	1995
Originator	Experimental economics tradition; Fehr & Gachter (cooperation and punishment)	Joyce Berg, John Dickhaut & Kevin McCabe
Type	Multi-player social-dilemma paradigm	Behavioral economic game as a social-psychology paradigm
Seminal source	Fehr, E., & Gachter, S. (2000). Cooperation and Punishment in Public Goods Experiments. American Economic Review, 90(4), 980-994.	Berg, J., Dickhaut, J., & McCabe, K. (1995). Trust, Reciprocity, and Social History. Games and Economic Behavior, 10(1), 122-142.
Aliases	Voluntary Contribution Mechanism, Common-Pool Contribution Game, Linear Public Goods Game	Investment Game, Berg Game, Two-Player Trust Game
Related	3	3
Summary	The public goods game is the canonical multi-person social dilemma used to study cooperation. Each member of a group is endowed with money and simultaneously decides how much to keep privately and how much to contribute to a common pool; the pool is multiplied and split equally among all members regardless of contribution. Because the marginal per-capita return is less than one but the group return exceeds one, every individual is privately better off free-riding while the group is collectively better off if all contribute -- the defining tension of a social dilemma. Experiments consistently show people contribute well above the self-interested zero, but contributions decay over repeated rounds unless institutions intervene. Fehr and Gachter's influential demonstration that allowing players to pay to punish free-riders restores and sustains high cooperation made the paradigm central to research on norms, altruistic punishment, and collective action.	The trust game, introduced by Berg, Dickhaut, and McCabe in 1995 (and often called the investment game), is a two-player exchange that operationalizes interpersonal trust and reciprocity in money. An investor receives an endowment and may send any portion to an anonymous trustee; the experimenter multiplies the transfer (typically tripling it); the trustee then decides how much, if any, to return. Standard game theory with purely self-interested players predicts the investor should send nothing because a selfish trustee returns nothing -- yet investors reliably send substantial amounts and trustees reliably return some, contradicting the narrow self-interest prediction. Because the amount sent cleanly measures trust and the amount returned measures trustworthiness, the paradigm became a workhorse in social psychology, behavioral economics, and neuroscience for studying social preferences and cooperation between strangers.