was not monitored. After one hour, the assistant came back and counted the number of entries.
At the end of the second occasion, payments were arranged and the student was asked to fill out
a short questionnaire. For each session, students received the pre-announced fixed wage of £10,
plus a performance bonus of 10p per table entry. Their total compensation was on average £13 per
session.
2.2 Treatments
Each one of the treatments that was part of our design involved the students performing the task in
two separate occasions, 60 minutes on each session. The two sessions were approximately 2 weeks
apart. Employing a within-subject design allows us to control for individual differences in typing
ability that might be present. We observe no attrition between sessions in our sample as all of the
students who were recruited turned up in both sessions. On the first occasion, all students were paid
on the basis described above, so that compensation depended on the amount of work performed.
There was no mention in the first occasion that a charitable donation might be introduced later.
On the second occasion students were randomized into three treatments7. Some underwent the
first treatment, which we call the Baseline treatment and serves as our control. In this condition
students were paid on the exact same basis as in the first session. The difference in output between
sessions 1 and 2 produced by those involved in this treatment is going to serve the benchmark
against which we are going to compare performance in the other treatments.
In Treatment A, students were offered the same personal compensation as in the Baseline Treat-
ment. Moreover, students were told that due to the funding of the project, in addition to their
personal compensation we were going to make a lump-sum donation to a charity of the student’s
choice (£15).8 It was explained to them that part of the lump-sum donation will be made on their
behalf based on their performance: for each table the charity received 30p on their behalf, while
the rest would be supplemented by us so that the charity received a total of £15.
Finally, in Treatment B, students were offered the same piece rate as in the Baseline Treatment
and, in addition, were told that a donation will be made to their preferred charity on their behalf
based on their performance: for each table they typed the charity would receive 30p on their
behalf. To ensure that each subject in Treatments A and B valued the cause to which the donation
7We check whether the distribution of observable characteristics is the same across treatments using a non-
parametric contingency table Pearson chi-square test. The gender composition is not significantly different across
treatments (p-value: 0.639), as is citizenship (p-value: 0.997), year of birth (p-value: 0.665), course of study (p-value:
0.525), year of study (p-value: 0.430).
8The list of charities used in the experiment is included in the Appendix.