Led by Centre researcher Janis Zickfeld, we conducted a megastudy in the UK & US (N = 21,506) to investigate this question: Dishonest behaviors such as tax evasion impose significant societal costs. In our study, we tested 21 honesty oaths, proposed and evaluated by 44 expert researchers, and a no-oath condition in which 21,506 participants played an incentivized tax evasion game.

Results showed that 10 of the interventions significantly improved tax compliance by 4.5 to 8.5 percentage points, with the most successful nearly halving tax evasion! Experts and laypeople failed to predict the most effective interventions, but experts’ predictions were more accurate. In conclusion, honesty oaths can be effective in curbing dishonesty but their effectiveness varies depending on content. These findings can help design impactful interventions to curb dishonesty.

Check out the preprint here.