Cooperation and Spillovers under Group-Level Regulatory Allocation

Last registered on March 05, 2026

View Trial History

Pre-Trial

Trial Information

General Information

Title

Cooperation and Spillovers under Group-Level Regulatory Allocation

RCT ID

AEARCTR-0018023

Initial registration date

March 02, 2026

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

March 05, 2026, 8:59 AM EST

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

Locations

Country

China

Region

Shanghai

Primary Investigator

Name

chenxi zhang

Affiliation

shanghai university of finance and economics

Contact Primary Investigator

Other Primary Investigator(s)

PI Name

Yao Lao

PI Affiliation

Shanghai university of finance and economics

Contact Investigator

Additional Trial Information

Status

Completed

Start date

2025-11-21

End date

2025-11-28

Keywords

Behavior

Additional Keywords

JEL code(s)

JEL Classification: C91, D91, D64

Secondary IDs

Prior work

This trial does not extend or rely on any prior RCTs.

Abstract

This study examines how regulatory interventions affect cooperation in repeated social dilemmas, with a particular focus on spillover effects that persist after external enforcement is removed. We employ a laboratory experiment in which 252 participants play a two-person finitely repeated Prisoner's Dilemma (T=90, R=60, P=55, S=10) over 24 rounds divided into two phases.In Phase 1 (Rounds 1–12), participants are randomly and fixedly matched and subject to one of five between-subjects treatments that vary the scope and information structure of a forced-compliance regulation mechanism. Unlike standard punishment mechanisms, the regulation imposes no financial penalties; instead, defection choices are automatically corrected to cooperation, allowing us to isolate the behavioral effects of regulation from deterrence. The five treatments are: No Monitor (baseline), Two Monitor (both partners monitored), One Monitor (one partner monitored with immediate disclosure), Random Monitor (one partner monitored with delayed disclosure), and Half Monitor (half of pairs fully monitored with delayed disclosure). In Phase 2 (Rounds 13–24), all regulation is removed and participants are re-matched with new partners, enabling identification of post-regulatory spillover effects.

External Link(s)

Registration Citation

Citation

Lao, Yao and chenxi zhang. 2026. "Cooperation and Spillovers under Group-Level Regulatory Allocation." AEA RCT Registry. March 05. https://doi.org/10.1257/rct.18023-1.0

Sponsors & Partners

Experimental Details

Interventions

Intervention(s)

The experiment implements five between-subjects treatments that vary the scope and information structure of a forced-compliance regulatory mechanism in Phase 1 (Rounds 1–12). In all treatments, if a monitored participant chooses to defect, the system automatically corrects the choice to cooperation; no financial penalty is imposed.
No Monitor (control): No regulation in either phase. Participants make unrestricted choices throughout.
Two Monitor: Both partners in each pair are monitored and subject to forced compliance in Phase 1. Monitoring status is disclosed to both parties before Phase 1 begins.
One Monitor: One participant per pair is randomly selected for monitoring in Phase 1. Both partners are informed of who is monitored before Phase 1 begins (immediate disclosure). At the start of Phase 2, participants are additionally informed of their new partner's Phase 1 monitoring status.
Random Monitor: One participant per pair is randomly monitored in Phase 1, but monitoring status is disclosed to participants only after Phase 1 ends (delayed disclosure). During Phase 1, participants are unaware of whether they or their partner are monitored.
Half Monitor: Half of all pairs are randomly selected for full monitoring (both partners) in Phase 1; the remaining pairs are unmonitored. Monitoring status is disclosed only after Phase 1 ends (delayed disclosure).
In Phase 2 (Rounds 13–24), all regulation is removed across all treatments. Participants are re-matched with new partners and play the Prisoner's Dilemma without any enforcement.

Intervention (Hidden)

Intervention Start Date

2025-11-21

Intervention End Date

2025-11-28

Primary Outcomes

Primary Outcomes (end points)

The binary cooperation decision (1 = cooperate, 0 = defect) in each round of Phase 1 (Rounds 1–12), aggregated as the individual-level average cooperation rate. This captures the direct effect of regulatory treatments on compliance-era behavior.

The binary cooperation decision in each round of Phase 2 (Rounds 13–24), aggregated as the individual-level average cooperation rate. This is the primary outcome of interest, capturing the spillover effect of Phase 1 regulatory experience on voluntary cooperation after enforcement is removed.

Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)

Secondary Outcomes (explanation)

Experimental Design

No Monitor (control): No regulation in either phase. Participants make unrestricted choices throughout.
Two Monitor: Both partners in each pair are monitored and subject to forced compliance in Phase 1. Monitoring status is disclosed to both parties before Phase 1 begins.
One Monitor: One participant per pair is randomly selected for monitoring in Phase 1. Both partners are informed of who is monitored before Phase 1 begins (immediate disclosure). At the start of Phase 2, participants are additionally informed of their new partner's Phase 1 monitoring status.
Random Monitor: One participant per pair is randomly monitored in Phase 1, but monitoring status is disclosed to participants only after Phase 1 ends (delayed disclosure). During Phase 1, participants are unaware of whether they or their partner are monitored.

Half Monitor: Half of all pairs are randomly selected for full monitoring (both partners) in Phase 1; the remaining pairs are unmonitored. Monitoring status is disclosed only after Phase 1 ends (delayed disclosure).

Experimental Design Details

Randomization Method

Treatment assignment was implemented at the session level via computer. Participants registered for experimental sessions without advance knowledge of treatment conditions. Each session was pre-assigned to a single treatment arm by the experimenter using a computer-generated randomization schedule prior to recruitment. Within each session, participant-to-partner matching was performed by the oTree using random assignment. For treatments involving individual-level monitoring (One Monitor, Random Monitor, Half Monitor), the software randomly determined which participant within each pair — or which pairs within the session — would be subject to the forced-compliance mechanism, with equal probability and without experimenter discretion.

Randomization Unit

The individual participant is the unit of randomization. Treatment assignment (No Monitor, Two Monitor, One Monitor, Random Monitor, Half Monitor) was conducted at the session level: each experimental session was assigned to a single treatment condition, and participants self-selected into sessions without knowledge of treatment assignment. Within-session randomization determined pair formation and, for applicable treatments, which member of each pair was monitored.

Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters

Not applicable. The experiment does not use a clustered design in the conventional sense. Randomization occurs at the session level; sessions range from 16 to 24 participants. A total of 11 sessions were conducted across the five treatment arms.

Sample size: planned number of observations

252 participants × 24 rounds = 6,048 participant-round observations in total.

Sample size (or number of clusters) by treatment arms

No Monitor (control): 60 participants
Two Monitor: 32 participants (all monitored)
One Monitor: 72 participants (36 monitored + 36 unmonitored in Phase 1)
Random Monitor: 44 participants (22 monitored + 22 unmonitored in Phase 1)
Half Monitor: 44 participants (24 monitored + 20 unmonitored in Phase 1)
Total: 252 participants

Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Supporting Documents and Materials

IRB