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Moral universalism as a signal

Last registered on May 26, 2022


Trial Information

General Information

Moral universalism as a signal
Initial registration date
May 06, 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
May 09, 2022, 8:22 PM EDT

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

Last updated
May 26, 2022, 3:09 PM EDT

Last updated is the most recent time when changes to the trial's registration were published.



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.
In this study we wish to explore the role of social signaling concerns in people's displayed moral universalism (the extent to which people display the same level of altruism toward in-group and out-group members). We use an online survey experiment to show that universalism is malleable to the presence and composition of one's audience.
External Link(s)

Registration Citation

Raux, Raphael. 2022. "Moral universalism as a signal." AEA RCT Registry. May 26.
Experimental Details


The intervention changes the presence and composition of subject's audience as they take a universalism decision. Meaning: the subject's universalism decision can either be made public or not to another subject, and this subject can either be an in-group or out-group member.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
The main outcome is the moral universalism decision: being given $1 to split between an in-group and out-group person, what fraction does the subject choose to give to the out-group person. Universalism is increasing in this fraction, and reaches its maximum with a 50-50 split. The main hypothesis is twofold: a) the public treatments will have a higher degree of displayed universalism than the private treatments; b) the public out-group treatment will have a higher degree of universalism than the public in-group treatment.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Subjects ("splitters") are matched with an "audience" member (another randomly-drawn subject), with whom they play a prisoner's dilemma game at the end of the survey. This audience can either be an in-group (fellow participant living in the U.S.) or out-group (fellow participant living anywhere else in the world) member.
Before playing the game, subjects ("splitters") are made to take a universalism decision (following Enke et al. 2020). This decision is either made public to the audience member, or kept private. Subjects have full knowledge of the intervention and the structure of the experiment.
There are therefore 4 treatment arms (public in-group; public out-group; private in-group; private out-group).
Experimental Design Details
Randomization Method
Randomization done by a computer.
Randomization Unit
Individual level for the 4 treatments. Subjects are also assigned to either the "splitters" or "audience" group, depending on which survey they see on the online platform.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
2 clusters: the "splitters" group and the "audience" group.
There are different surveys for "splitters" and "audiences", so conditional on taking part in a survey, the individual's cluster is already determined: subjects are then assigned randomly to one of the 4 treatment arms.
Sample size: planned number of observations
Around 800 "splitters", and around 160 "audiences", for a total of around 960 subjects. Each audience member is matched with 5 splitters. A little bit more than 960 subjects might be recruited to account for inattentive responses. Update: due to a large number of low-quality (inattentive or rushed) answers, especially in the two "public" treatment arms, an extra 600 splitters are recruited (along with an extra 120 audiences), so as to obtain around 200 high-quality responses per treatment. This put the total number of subjects to around 1680.
Sample size (or number of clusters) by treatment arms
Each treatment arm will have around 200 "splitters" and 40 "audiences". There are 4 treatment arms.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
Harvard - Committee on the Use of Human Subjects
IRB Approval Date
IRB Approval Number


Post Trial Information

Study Withdrawal

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Is the intervention completed?
Intervention Completion Date
June 10, 2022, 12:00 +00:00
Data Collection Complete
Data Collection Completion Date
June 10, 2022, 12:00 +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
4 treatments
Was attrition correlated with treatment status?
Final Sample Size: Total Number of Observations
889 splitters and 988 audiences
Final Sample Size (or Number of Clusters) by Treatment Arms
207, 214, 238, 230 respectively for private-in, private-out, public-in, public-out. Slightly more subjects were recruited for the public treatments because a larger share failed comprehension questions for those.
Data Publication

Data Publication

Is public data available?

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Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials