The role of payoff parameters for cooperation in the one-shot prisoner’s dilemma

Last registered on August 03, 2022

Pre-Trial

Trial Information

General Information

Title
The role of payoff parameters for cooperation in the one-shot prisoner’s dilemma
RCT ID
AEARCTR-0009784
Initial registration date
July 29, 2022

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
August 03, 2022, 1:27 PM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

Region

Primary Investigator

Affiliation
University of Nottingham

Other Primary Investigator(s)

PI Affiliation
Bank of Korea
PI Affiliation
University of Nottingham
PI Affiliation
Newcastle University

Additional Trial Information

Status
In development
Start date
2022-08-02
End date
2022-08-16
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
This study investigates the effect of variation in material payoffs on cooperation in experimental one-shot Prisoner’s Dilemma (PD) games. Following Mengel (2018) we vary three payoff indices. Indices of risk and temptation capture the unilateral incentives to defect against defectors and co-operators respectively, while an index of efficiency captures the gains from cooperation. In a previous analysis, we found that risk has no effect on cooperation, temptation reduces cooperation, and efficiency increases cooperation. Here we provide a confirmatory analysis of these results using a between-subjects design that varies payoff parameters in an orthogonal way and where participants will play one one-shot game.
External Link(s)

Registration Citation

Citation
Gaechter, Simon et al. 2022. "The role of payoff parameters for cooperation in the one-shot prisoner’s dilemma." AEA RCT Registry. August 03. https://doi.org/10.1257/rct.9784
Experimental Details

Interventions

Intervention(s)
Intervention Start Date
2022-08-02
Intervention End Date
2022-08-16

Primary Outcomes

Primary Outcomes (end points)
The decisions to cooperate or defect in a one-shot prisoner's dilemma game
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Beliefs about others' cooperation or defection decision in a one-shot prisoner's dilemma game
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Pairs of participants play one one-shot Prisoner’s Dilemma game. We have a between-subjects design with 8 prisoner's dilemma games. We vary the PD’s payoff matrix across the eight games as shown below:

G1: T=600; R=500; P=200; S=90
G2: T=600; R=500; P=200; S=20
G3: T=800; R=500; P=200; S=90
G4: T=800; R=500; P=200; S=20
G5: T=600; R=500; P=400; S=180
G6: T=600; R=500; P=400; S=40
G7: T=800; R=500; P=400; S=180
G8: T=800; R=500; P=400; S=40

Notes: S=Temptation payoff; R=Reward payoff, P=Punishment payoff, S=Sucker payoff. Payoffs in experimental currency.

Participants will be randomly matched into pairs and to one of the eight games.

Participants will be asked to complete two tasks: (1) Choose whether to cooperate or defect in the Prisoner’s Dilemma game, and (2) indicate the likelihood that the other person will choose to cooperate. The choices will be neutrally labeled as A and B. The order of tasks and choices will be randomised.

After taking part in the prisoner’s dilemma game, participants will be asked to complete a socio-economic background questionnaire.

The experiment will be run on Amazon Mechanical Turk with 200 participants in each of the 8 games, that is, with a total of 1,600 participants. The experiment is programmed with the software LIONESS Lab (https://lioness-lab.org/).
Experimental Design Details
Randomization Method
The software will randomly allocate participants at the pair-level.
Randomization Unit
Individuals will be randomly matched into pairs and to one of the eight one-shot prisoner's dilemma games.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
200 participants for each of the 8 games
Sample size: planned number of observations
1,600 participants
Sample size (or number of clusters) by treatment arms
200 for each of the 8 games
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
In a previous analysis, temptation emerged as the most important of the three indices in explaining cooperation. The cooperation rate under low tempt was 0.4 vs 0.6 under high tempt. We aim to be able to replicate this treatment difference in cooperation rates with alpha = 0.05 and a power of 95%. We conducted a power analysis with Stata’s “power” for a two-sided test of proportions. The Stata command power twoprop 0.4 0.6, alpha(0.05) power(0.95) yields a calculated sample size of 160 per treatment. To account for heterogeneity on MTurk, we plan to recruit 200 participants for each of the 8 treatments.
Supporting Documents and Materials

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IRB

Institutional Review Boards (IRBs)

IRB Name
The Nottingham School of Economics Research Ethics Committee
IRB Approval Date
2022-06-23
IRB Approval Number
ERCP-2022-012-oneshot
Analysis Plan

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Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials