手法を比較

	Public Goods Game	Minimal Group Paradigm
分野	社会心理学	社会心理学
系統	Process / pipeline	Process / pipeline
提唱年	2000	1971
提唱者	Experimental economics tradition; Fehr & Gachter (cooperation and punishment)	Henri Tajfel and colleagues
種類	Multi-player social-dilemma paradigm	Experimental paradigm for intergroup discrimination
原典	Fehr, E., & Gachter, S. (2000). Cooperation and Punishment in Public Goods Experiments. American Economic Review, 90(4), 980-994.	Tajfel, H., Billig, M. G., Bundy, R. P., & Flament, C. (1971). Social categorization and intergroup behaviour. European Journal of Social Psychology, 1(2), 149-178.
別名	Voluntary Contribution Mechanism, Common-Pool Contribution Game, Linear Public Goods Game	Minimal Group Experiment, Tajfel Matrices, Mere Categorization Paradigm
関連	3	3
概要	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 minimal group paradigm is an experimental procedure, introduced by Henri Tajfel and colleagues in 1971, that strips intergroup conflict down to its barest possible cause: mere categorization. Participants are sorted into two groups on a trivial or random basis (for example, an alleged preference for one painter over another, or a coin toss), never meet other members, gain nothing personally, and then allocate points between anonymous in-group and out-group members using structured reward matrices. The striking and repeatedly replicated finding is that people favor their own group even when the category is meaningless and favoritism brings them no material gain. The paradigm became the empirical cornerstone of social identity theory, demonstrating that the cognitive act of dividing the social world into 'us' and 'them' is itself sufficient to produce discrimination.