The HED Task Catalog is under development. IDs are not stable until formal release. Comments are welcome at github.com/hed-standard/hed-task/issues.

Prisoner’s Dilemma Task

HED task ID: hedtsk_prisoners_dilemma

Family: Social cognition and social choice tasks

Also known as: Prisoner’s Dilemma, PD, Iterated Prisoner’s Dilemma, Iterated PD

Two-player one-shot or iterated game with cooperate/defect choices and asymmetric payoffs; choice patterns index cooperation and strategic reasoning.

Description

The Prisoner’s Dilemma is a canonical game theory paradigm for studying cooperation and defection under strategic interdependence. Two players simultaneously choose to cooperate or defect. Mutual cooperation yields moderate rewards for both; mutual defection yields low rewards for both; but if one defects while the other cooperates, the defector receives the highest reward and the cooperator receives nothing (or a penalty). The dominant strategy in single-shot play is to defect, yet human participants frequently cooperate, particularly in iterated versions. The task is central to research on trust, reciprocity, altruism, and the neural substrates of social decision-making.

Inclusion test

An experiment is an instance of this task when its procedure matches, it manipulates at least one of the listed variables, and it records at least one of the listed measures.

Procedure	Two players simultaneously choose to cooperate or defect; payoffs depend on both choices according to a matrix where mutual cooperation beats mutual defection but defection is individually tempting.
Manipulation	Payoff matrix values; one-shot vs. iterated; partner identity (human, computer, in-group); communication allowed or not.
Measurement	Cooperation rate; payoff earned; tit-for-tat and other strategy classification; first-move cooperation.

Variations

Named versions that change what the participant experiences or does. The identifier of a variation is hedvar_<task>__<variation>.

Variation	Description	Justification
Single-Shot (One-Round) PD hedvar_prisoners_dilemma__single_shot_one_round_pd	One simultaneous decision; tests baseline cooperation rates.	Canonical one-round anonymous PD; no reputation effects
Iterated PD (Repeated Games) hedvar_prisoners_dilemma__iterated_pd_repeated_games	Multiple rounds with same partner; enables tit-for-tat strategies.	Multiple rounds with same partner; reputation and strategy accumulate
Sequential PD hedvar_prisoners_dilemma__sequential_pd	One player decides first, then the other; introduces trust asymmetry.	One player acts before observing other’s choice; different temporal structure
Multiplayer/Public Goods Version hedvar_prisoners_dilemma__multiplayer_public_goods_version	N-player generalization; contribute to a common pool.	More than two players; group dilemma structure
PD with Communication hedvar_prisoners_dilemma__pd_with_communication	Cheap talk or binding communication before decisions.	Players communicate before deciding; cheap talk changes decision context
PD with Punishment Option hedvar_prisoners_dilemma__pd_with_punishment_option	Third-party or second-party punishment of defectors.	Third-party punishment available; adds enforcement mechanism
PD with Varying Payoff Matrices hedvar_prisoners_dilemma__pd_with_varying_payoff_matrices	Manipulating temptation-to-defect and cooperation incentives parametrically.	Different temptation/sucker payoffs; tests sensitivity to game parameters
PD against Computer Opponents hedvar_prisoners_dilemma__pd_against_computer_opponents	Known strategies (always cooperate, always defect, tit-for-tat).	Computer opponent instead of human; per §5.6 structural change (deterministic vs. human partner)
PD with Reputation Information hedvar_prisoners_dilemma__pd_with_reputation_information	Partners’ cooperation histories visible; tests reputation effects.	Partner’s past cooperation history visible; changes social information available
Continuous PD hedvar_prisoners_dilemma__continuous_pd	Graded cooperation rather than binary cooperate/defect.	Continuous contribution instead of binary; different action space
Asymmetric Prisoner’s Dilemma hedvar_prisoners_dilemma__asymmetric_prisoners_dilemma	Payoffs do not mirror each other; one player gains more or loses less from defection, introducing inequity into the strategic calculus.	Different payoff structures for each player; breaks symmetry of standard PD
Optional Prisoner’s Dilemma hedvar_prisoners_dilemma__optional_prisoners_dilemma	Players can opt out of the interaction entirely, receiving a safe intermediate payoff; opt-out availability typically increases cooperation among those who choose to play.	Third option to not participate; changes strategic choice set

Cognitive processes

This task is designed to engage the following processes:

• Social decision making

• Cooperation

• Competition

• Reciprocity

• Strategy use

• Perspective taking

Key references

• Rilling, J. K., Gutman, D. A., Zeh, T. R., Pagnoni, G., Berns, G. S., & Kilts, C. D. (2002). A neural basis for social cooperation. Neuron, 35(2), 395–405. (DOI, PubMed)

• Fehr, E., & Fischbacher, U. (2003). The nature of human altruism. Nature, 425(6960), 785–791. (DOI, PubMed)

Further references

• Rand, D. G., & Nowak, M. A. (2013). Human cooperation. Trends in Cognitive Sciences, 17(8), 413–425. (DOI, PubMed)

• Engel, C., & Zhurakhovska, L. (2016). When is the risk of cooperation worth taking? The prisoner’s dilemma as a game of multiple motives. Applied Economics Letters, 23(16), 1157–1161. (DOI)

• Declerck, C. H., Boone, C., & Emonds, G. (2013). When do people cooperate? The neuroeconomics of prosocial decision making. Brain and Cognition, 81(1), 95–117. (DOI, PubMed)

• Peysakhovich, A., Nowak, M. A., & Rand, D. G. (2014). Humans display a ‘cooperative phenotype’ that is domain general and temporally stable. Nature Communications, 5, 4939. (DOI, PubMed)

External links

• Cognitive Atlas: prisoner’s dilemma (PD)