2 Experimental Design
2.1 Recruitment and Task
The experiment was conducted with undergraduate students recruited through email announce-
ments at the University of Southampton in the fall term of 2008. The job ad was asking for
students interested in assisting with data entry for a research project in economics. The announce-
ment stated that no prior experience was needed other than basic typing and some familiarity
with Microsoft Excel and that interested students should be able to work for a period of 2 hours
on two separate occasions over a four-week period. The email also indicated that compensation
would include a £10 fixed-fee for each session plus a performance bonus. Interested students were
asked to respond indicating their availability, and selection among respondents was based on this
information. In total we recruited 71 students of diverse academic backgrounds - Computer Science,
Biology, Social Sciences and Engineering - excluding Economics. It is worth noting that students
were unaware ex-ante that they were participating in an experiment.
The task consisted of typing data contained in input-output tables that the student received in
a booklet into an Excel Worksheet.5 Each table consisted of 48 randomly generated 3-digit numbers
(2 decimals) that always added up to 100. Each table in the booklet and the worksheet is identified
by a date (e.g. Jan 1953) and students had to enter each table frame in the corresponding worksheet.
For each table, students were told not to enter the last column and row, as these were automatically
calculated by Excel, but were asked to check that the numerical values calculated by Excel for the
last column and row corresponded to the ones on the booklet and that the value in the bottom right
cell equalled 100. The worksheet also contained a counter which tracked the number of completed
tables, the student’s compensation and the donation amount when applicable.6 This particular data
entry task was chosen such that performance is perfectly measurable (number of table entries), and
did not allow for cooperation or teamwork, as each participant worked separately without knowing
what other participants were doing or even how many other participants were involved. This has
the advantage of removing possible confounding factors related to peer pressure. The task was
performed in a standard university office on a desktop computer.
We employed 3 research assistants to give instructions and supervise student workers (each
student was supervised by the same assistant on both occasions). The research assistants after
greeting the student and introducing the task left the office so that during working time the student
5See the attached Instructions sheet given to subjects for a more detailed description of the task.
6A screen-shot of the worksheet used for data entry is included in the Appendix.