One example is a scenario in which the electricity has gone out for an entire neighborhood. All inhabitants know that the electricity company will fix the problem as long as at least one person calls to notify them, at some cost. If no one volunteers, the worst possible outcome is obtained for all participants. If any one person elects to volunteer, the rest benefit by not doing so.
A public good is only produced if at least one person volunteers to pay an arbitrary cost. In this game, bystanders decide independently on whether to sacrifice themselves for the benefit of the group. Because the volunteer receives no benefit, there is a greater incentive for freeriding than to sacrifice oneself for the group. If no one volunteers, everyone loses. The social phenomena of the bystander effect and diffusion of responsibility heavily relate to the volunteer’s dilemma.
The payoff matrix for the game is shown below:
|at least one other person cooperates||all others defect|
When the volunteer's dilemma takes place between only two players, the game gets the character of the game 'chicken'. As seen by the payoff matrix, there is no dominant strategy in the volunteer’s dilemma. In a mixed-strategy Nash equilibrium, an increase in N players will reduce the likelihood that any one player volunteers and will decrease the likelihood that at least one person volunteers, which is a result of the bystander effect.
Examples in real life
The story of Kitty Genovese is often used as a classic example of the volunteer's dilemma. Genovese was stabbed to death in an alley where various residential apartments overlooked the assault. Although many people were aware of the assault at the time (even though they may not have been aware of the exact scope and nature of the assault), only one person contacted the police.
It was assumed that people did not get involved because they thought others would contact the police and people did not want to incur the costs of getting involved in the dispute.
The meerkat exhibits the volunteer's dilemma in nature. One or more meerkats act as sentries while the others forage for food. If a predator approaches, the sentry meerkat lets out a warning call so the others can burrow to safety. However, the altruism of this meerkat puts it at risk of being discovered by the predator.