Abatement allocation under moral suasion and financial incentives

Last registered on May 07, 2021


Trial Information

General Information

Abatement allocation under moral suasion and financial incentives
Initial registration date
May 06, 2021

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 07, 2021, 10:33 AM EDT

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



Primary Investigator

University of Neuch√Ętel

Other Primary Investigator(s)

PI Affiliation
University of Neuch√Ętel
PI Affiliation
University of Kobe

Additional Trial Information

In development
Start date
End date
Secondary IDs
We study prosocial behavior under moral suasion and monetary incentives. We employ an incentivized online experiment with (i) a real effort task (ii) a multiple price list task and (iii) a social norm elicitation task. Our results contribute to the understanding of how prosocial behavior respond to external interventions.
External Link(s)

Registration Citation

Elbaum, Jean-David, Bruno Lanz and Hiro Sakamoto. 2021. "Abatement allocation under moral suasion and financial incentives." AEA RCT Registry. May 07. https://doi.org/10.1257/rct.7554-1.0
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Experimental Details


The online experiment is conducted with a representative panel of Swiss households managed by a professional public opinion company. Participants in the survey are remunerated CHF 6 for completing the survey, plus possible monetary gains from the experiment. In the core experiment, participants perform a simple key-pressing task and can be randomly assigned into one of two control groups or 12 treatment arms. Each treatment differs with respect to the incentives associated with the key-pressing task. In addition, a separate group of participants is assigned to a social norm elicitation task.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Performance in the button-clicking task, willingness to pay for CO2 abatement, social norms associated with carbon abatement.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We will run three tasks. The first task is a real effort task where participants successively click the "a" and "b" buttons during 5 minutes. The second task is a multiple price list. The third task is applied to a separate sample to determine the social norm of taking money over abating CO2.
Experimental Design Details
Each participant in the main experiment goes through a sequence of two tasks, only one of them being (randomly) selected for implementation / payment.

The first and main task is a real effort task where subjects successively press "a" and "b" on their keyboard as many times as possible, each pair earning one point. In treatment, each point corresponds to a pre-specified amount of CO2 being removed from the atmosphere. After a 30 seconds training period, this task lasts for 5 minutes although participants can elect to finish early.

In the main task, all participants face an increasing marginal abatement cost curve. This implies that the amount of CO2 abatement per point scored declines with the cumulative number of points achieved. Moreover, to study how alternative external interventions affect the distribution of abatement effort accross heterogenous agents, participants can be in either of two groups (randomly selected). In group A, the "low abatement cost" group, each point scored by a participant implies a relatively high abatement. In group B, the "high abatement cost", the amount of CO2 removed is eight times smaller. See hereunder the abatement schedules for both groups:

Group A (number of pairs: abatement in kg of CO2 per pair of keys)
0-200: 2
201-400: 1
401-600: 0.5
601-800: 0.25
801-1,000: 0.125
1,001+: 0.06

Group B (number of pairs: abatement in kg of CO2 per pair of keys)
0-200: 0.25
201-400: 0.125
401-600: 0.06
601-800: 0.03
801-1,000: 0.015
1,001+: 0.01

Participants are randomly assigned to either a control group with two conditions or to one of 12 experimental treatments. The latter combine six possible conditions for each abatement schedule (groups A and B).

Respondents in the control groups face a neutral frame, meaning that the information they receive does not refer to CO2. In the first control group, participants simply receive an explanation about the key-pressing task. It is explicitly said that their score does not affect their CO2 abatement nor their monetary payment. This group allows to identify the baseline willingness to exert an effort. In the second control condition, participants are incentivized with direct monetary incentives. Specifically, they receive the same information about the key-pressing task and receive additional information about the payment received for each points they score. The payment schedule is following (in cents per point):

0-200: 2.5
201-400: 1.25
401-600: 0.6
601-800: 0.3
801-1000: 0.15
1001+: 0.1

This condition allows to quantify how effort is affected to monetary incentives in a neutral frame.

Each of the following 12 conditions (6 conditions per abatement schedule) refers to CO2.

In the first treatment condition, named "Voluntary CO2 abatement", participants receive information about the key-pressing task and additional information about the CO2 abatement schedule (either group A or B). We also explain that they will receive a proof of CO2 certificates corresponding to the abatement effort achieved in the experiment. In addition, we provide some basic background information about CO2 emissions in Switzerland.

The second treatment condition is named "Moral suasion". In this condition, participants receive information about the key-pressing task and CO2 emissions (as in condition voluntary CO2 abatement). Additional text motivates abatement effort by calling upon moral justice. This condition is intended to affect intrinsic motivation for voluntary abatement effort. The message explicitly links carbon abatement, moral duty and climate justice.

The following treatment condition is called "Monetary incentives". In this treatment, participants receive the same information as in the voluntary CO2 abatement condition, and we incentivize CO2 abatement using two different carbon prices. First, we consider CHF12.5 per tonne CO2, which gives rise to following per point payment schedule (in cents per point):

Group A / Group B:
0-200: 2.5 / 0.3
201-400: 1.25 / 0.15
401-600: 0.6 / 0.1
601-800: 0.3 / 0.05
801-1000: 0.15 / 0.02
1001+: 0.1 / 0.01

The second price of CO2 is set at CHF100 per tonne CO2, which gives rise to a second payment schedule (in cents per point):

Group A / Group B:
0-200: 20 / 2.5
201-400: 10 / 1.25
401-600: 5 / 0.6
601-800: 2.5 / 0.3
801-1000: 1.25 / 0.15
1001+: 0.6 / 0.1

The last two treatment conditions combine the textual message incentivizing moral behavior and one of the two financial incentives of the monetary incentives condition. This treatment allows to test whether monetary incentives crowd-out intrinsic motivation activated with the moral suasion message.

A third task, applied to a separate, determines the perceived moral duty associated with CO2 abatement. In this task, subjects are asked to rate the choice of choosing CHF100 over abating 0.5 tonne of CO2 as "socially acceptable and consistent with moral and appropriate behavior" from "socially inacceptable and inconsistent with moral and appropriate behavior". Importantly, respondents are asked to rate what other subjects would think about the statement rather than own preferences. Participants who match the modal response elicited in the pilot receive CHF 10.
Randomization Method
Randomization is done through Qualtrics pseudo-random number generator.
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
1 cluster of online respondants
Sample size: planned number of observations
Around 2,000 online respondents
Sample size (or number of clusters) by treatment arms
Around 130 participant per treatment and around 100 for social norm elicitations task
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number


Post Trial Information

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

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Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials