In their famous study, The Dishonesty of Honest People: A Theory of Self-concept Maintenance, researchers Nina Mazar, On Amir and Dan Ariely asked participants to either recall the 10 Commandments or 10 books they had read at school before giving them an opportunity and incentive to cheat on a problem-solving task. Participants who were primed with a moral reminder (the 10 commandments) were less likely to cheat than those who received no such primer. Since then, this frequently cited study has become influential in psychology, but also in marketing and economics.

Large-scale replication

In 2017 the Netherlands Organisation for Scientific Research (NWO) awarded funding for a replication of the original study as part of a wider drive to fund replication research. The project, led by Bruno Verschuere from the UvA and Ewout Meijer from UM, consisted of a team of 68 researchers from 25 labs across 14 countries. All 25 labs conducted a direct replication of the study using a protocol vetted and approved by the original authors.

Following the procedures used in the original study, the replication project presented participants with a problem-solving task consisting of 20 puzzles. Each participant was instructed to solve as many puzzles as possible within four minutes and told that 2 participants chosen at random would be given $10 for each correctly solved puzzle, making it possible to win $200. Before starting, participants were primed by asking them either to recall as many 10 Commandments or 10 books as they could.

No evidence that moral reminders reduce cheating

‘The primary, preregistered analyses on 4,647 participants showed that a moral reminder in the form of recalling the 10 Commandments did not diminish cheating’, says Verschuere, who is associate professor of Forensic Psychology. ‘This finding was confirmed by two ancillary analyses in which the 10 Commandment effect was shown to be close to zero. The moral reminder also proved to have no effect in labs with more religious participants, despite our expectation that the 10 Commandment effect would be more readily apparent for participants with stronger religious beliefs.’

But why the different outcome? Verschuere: ‘There are always differences between an original study and replication research. You cannot step in the same river twice. For instance, the original study was conducted more than a decade ago at an elite university. The perceived rewards, the perceived probability of getting caught and the perceived consequences of getting caught may have been different for participants in our replication study. We also need to consider the possibility that the effect does not exist, and that the original result was a chance finding.’

The importance of replication research

Besides questioning the efficacy of using the 10 Commandments as a moral prime to reduce cheating, the results show the importance of replication research, says Verschuere. ‘The psychology theory of cheating is very appealing, but we need more replication research to establish the reliability of its empirical basis. Moreover, our results show the importance of open science practices. Our study wouldn’t have been possible without the help of the original authors who sent us their material and answered many questions on their procedures. That said, it is undesirable that replication teams depend on the willingness and memory of the original authors. The materials and data should rather be made publicly available immediately upon publication.’

Publication details

Verschuere, B., Meijer, E. H., Jim, A., McCarthy, R., Hoogesteyn, K., Skowronski, J., Orthey, R., Acar, O. A , (…), Yıldız, E. (2018). Registered Replication Report: Mazar, N., Amir, O., & Ariely, D. (2008). Advances in Methods and Practices in Psychological Science. Manuscript in press.