Authors’ contributions
R H-J, AB, SJ, PM, KT and TC conceived of the studies, R H-J implemented the studies and wrote the first draft of the paper, NG managed the data analysis and wrote up Study 1 and revised the manuscript, KT reviewed drafts of the letters and did data cleaning and preliminary statistical analysis, AS performed the randomization and gave statistical oversight, RW did statistical analysis for study 1, SB did statistical analysis for study 2, KB reran and checked the statistical analyses and helped revise the manuscript. The author(s) read and approved the final manuscript.