Note: A final version of this research has been published (link and reference below).Link: https://www.pnas.org/content/pnas/early/2020/07/24/2009030117.full.pdfReference: Heck, P.R., Watts, D., Chabris, C.F., & Meyer, M.N. (2020). Objecting to experiments even while approving of the policies or treatments they compare. Proceedings of the National Academy of Sciences. Online first. https://doi.org/10.1073/pnas.2009030117Across three studies that revealed the A/B Effect using a between-subjects design in Meyer et al. (2019), we find via corresponding within-subjects designs that the A/B Effect persists even when participants (1) have complete information about the options available to a decision-maker (i.e., to implement policy A for everyone or policy B for everyone, or to run an A/B test between them and use the results to choose the best policy), (2) rate the appropriateness of these decisions after being able to consider all of them, and (3) rank-order the soundness of the decisions to run an A/B test or implement an untested policy. The result held across three domains: two healthcare (a hospital and a walk-in clinic) and one corporate (a direct-to-consumer genetic testing company). Importantly, the results were robust to increasing levels of conservativeness in the critical test for the presence of an effect.