A type of social dilemma in which members of a group choose whether or how much to contribute to something from which all group members benefit equally. In a classical (and typical) experiment, nine participants or subjects were given $5 each, and the rules specified that if five or more of them contributed their money to a central fund, then all nine participants would receive a $10 bonus whether or not they had contributed. If enough people contributed, the net payoff, taking into account contributions paid in, was $10 to a contributor and $15 to a non-contributor, but if too few contributed, the payoff was zero to a contributor and $5 to a non-contributor. Public goods games are designed to simulate subscription payments to unions and other social dilemmas in which all members of a group benefit from actions that are costly to the individuals who make them. They are also called free-rider problems, and the corresponding experimental games are sometimes called give-some games.