Signing at the beginning makes ethics salient and decreases dishonest self-reports in comparison to signing at the end
Proceedings of the National Academy of Sciences (2012) - Comments
doi: 10.1073/pnas.1209746109  issn: 0027-8424  issn: 1091-6490  pubmed: 22927408 

Lisa L. Shu, Nina Mazar, Francesca Gino, Dan Ariely, Max H. Bazerman