Randomized trial seeking to induce the Hawthorne effect found no evidence for any effect on self-reported alcohol consumption online

Objective: We tested the hypothesis that participants who know the behavioral focus of a study and are thus aware that a particular behavior is being studied will modify that behavior, independently of any possible effect of assessment, thereby dismantling a Hawthorne effect into two putative components. Study Design and Setting: We undertook a three-arm individually randomized trial online among students: group A (control) were told they were completing a lifestyle survey; group B were told the focus of the survey was alcohol consumption; and group C additionally answered 20 questions on their alcohol use and its consequences before answering the same lifestyle questions as Groups A and B. Nondrinkers were excluded, and all groups were aware they would be followed up after 1 month. Results: Outcome data were obtained for 4,583 of 5,478 trial participants (84% follow-up rate). There were no differences between the three groups on primary (overall volume consumed) or secondary outcome measures (drinking frequency and amount per typical occasion) in the intervening 4 weeks. Conclusions: There is no evidence that any form of Hawthorne effect exists in relation to self-reported alcohol consumption online among university students in usual research practice. Attention to study contexts is warranted for investigating research participation effects.