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

Last registered on August 03, 2022

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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

Country

United States of America

Region

Primary Investigator

Name

Simon Gaechter

Affiliation

University of Nottingham

Contact Primary Investigator

Other Primary Investigator(s)

PI Name

Kyeongtae Lee

PI Affiliation

Bank of Korea

Contact Investigator

PI Name

Martin Sefton

PI Affiliation

University of Nottingham

Contact Investigator

PI Name

Till O. Weber

PI Affiliation

Newcastle University

Contact Investigator

Additional Trial Information

Status

In development

Start date

2022-08-02

End date

2022-08-16

Keywords

Behavior, Lab

Additional Keywords

prisoner's dilemma, cooperation, payoff parameters, online experiment

JEL code(s)

A13, C91

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.9784-1.0

Sponsors & Partners

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

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?

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.

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