Turning opposition into support to immigration: the role of social norms

Last registered on April 24, 2020


Trial Information

General Information

Turning opposition into support to immigration: the role of social norms
Initial registration date
April 23, 2020

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
April 24, 2020, 3:05 PM EDT

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



Primary Investigator


Other Primary Investigator(s)

PI Affiliation

Additional Trial Information

In development
Start date
End date
Secondary IDs
The number of migrants moving from one country to another is bound to increase, and a considerable fraction of these flows will try to access the European countries. At the same time, public opinion towards immigration is often negative. A supportive public approach has many advantages, as it can facilitate an efficient management of the migration flows and improve the integration of migrants in our societies. Building on a theoretical model, we study a set of experimental treatments aimed at promoting support to immigration through a mechanism based on social norms. Our intervention consists of presenting a favourable social norm prevailing among the members of an "ingroup" (the natives) and test its effectiveness in reducing the social distance between a subject belonging to the ingroup and the "outgroup" (the migrants). Receiving a favourable social norm is expected to deliver a clear sign that peers of the ingroup are not against migrants, ultimately affecting behaviour.
External Link(s)

Registration Citation

Cattaneo, Cristina and Daniela Grieco. 2020. "Turning opposition into support to immigration: the role of social norms." AEA RCT Registry. April 24. https://doi.org/10.1257/rct.5754-1.0
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
The outcomes variables of the experiment are actual behaviours. We measure actual behaviour by measuring the willingness to donate part of the endowment to a non-profit organization operating pro-migrants. As a second measure of actual behaviour, we will check the respondents' willingness to sign a petition in favour of migrants and their actual signature, providing a link to the real petition. The order of the two outcome (petition and donation) will be randomized.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We plan to conduct an incentivized survey and recruit Italian participants through a commercial firm which will ensure the representativeness of the sample. Respondents in the treatment groups will receive information on the social norm, namely on what other respondents did before them in terms of donation to a charity operating in favour of migrants. Moreover, to understand to what extent the social norm is effective in changing donations per se, or due to its capability to convey information on the ingroup attitude towards the outgroup, we will also design a treatment where we directly provide information on the ingroup (favourable) attitude towards the outgroup. In the Control treatment respondentswill not receive any information on previous respondents’ behaviour or attitude.
Experimental Design Details
Randomization Method
Even randomization between subjects, in the different groups, done by the survey firm.
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
Ethics Committee of the University of Milano
IRB Approval Date
IRB Approval Number
protocol n. 20-20, April 2, 2020
Analysis Plan

Analysis Plan Documents


MD5: e1e89e5ec4c3faf6562496d4291d5b4c

SHA1: 1e10b332b51da80fd265a9394e0b4b7dcf1bbf6a

Uploaded At: April 23, 2020


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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