Relational Mobility Leads to Altruism

Last registered on July 20, 2023


Trial Information

General Information

Relational Mobility Leads to Altruism
Initial registration date
July 17, 2023

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
July 20, 2023, 3:12 PM EDT

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


Primary Investigator

Harvard University

Other Primary Investigator(s)

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Do relational mobility affect people's degree of altruism in prisoner's dilemma? In this study, subjects are matched in pairs to play repeated prisoner's dilemma, and some subjects are allowed to change partners (i.e. they are relationally mobile). The study aims to investigate whether mobile players more altruistic or less, and how much of people's altruism can be attributed to mobility as opposed to other factors.

In terms of data collection, I will send out surveys to ask for people's game strategies, and subjects will be informed whether they have relational mobility or not prior to specifying their strategies. I will then collect their strategies, pay the subjects by the amount of money their strategies generate, and look at how different game conditions change the strategies submitted by the subjects.
External Link(s)

Registration Citation

Lu, Ziqi. 2023. "Relational Mobility Leads to Altruism." AEA RCT Registry. July 20.
Experimental Details


Subjects are asked to provide their strategies in a pairwise 2-period non-cooperative game. The treated subjects will have an option to change the partner they are playing with after the first period, while the controls have to play with the same partners for both periods.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Number of points each player gave out at the beginning.
Primary Outcomes (explanation)
1. Degree of altruism: number of points giving out at the beginning.
2. Altruism explained by mobility: the regression estimation of mobility's effect on altruism after controlled for demographics and expectation on other's altruism.

Secondary Outcomes

Secondary Outcomes (end points)
1. The number of points given at round 2.
2. The number of points below which players would switch partners.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Subjects are asked to provide their strategies in a pairwise 2-period gift-exchange game. In each of the two periods, both players will simultaneously and unconditionally give 0 to 100 points to her partner, and the experimenter adds 50% to it. At the end of Round 1, the treated subjects will have an option to leave the partner they are playing with by indicating a threshold of points: if their partners give less than the threshold, they will switch partners, and each of them will be assigned a random new partner. The controls have to play with the same partners for both periods.

Each subject is also asked about how much she expects her partner to give her.

The key hypothesis is that subjects in the treatment group (with mobility) give more in round 1 than subjects in the control group (without mobility).
Experimental Design Details
Randomization Method
Computer randomization
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
2,000 individuals
Sample size: planned number of observations
2,400 individuals
Sample size (or number of clusters) by treatment arms
1,200 individuals control
1,200 individuals treatment
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
The size of the effect is estimated to be 2.3 points with a standard deviation of 32, and I will need around 2,400 individuals to detect an effect with a significance level of around 1%.

Institutional Review Boards (IRBs)

IRB Name
Mobility Leads to Altruism
IRB Approval Date
IRB Approval Number


Post Trial Information

Study Withdrawal

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials