Randomization, Masking, and Enrollment
LGA
Participants who passed all quality control checks were randomized to 1 of the 2 study arms. The intervention arm (arm 1) contained an image of a social media post about face masks for reducing COVID-19 transmission that included both cognitive and normative claims. The control arm (arm 2) contained the same image except that it did not include the normative claim. Both images were otherwise identical.Prolific fully managed enrollment. Individuals who were enrolled accessed a link that we provided to our study in the online study platform Qualtrics XM (Qualtrics International Inc). Participants who were not rejected by quality control were randomized using the Qualtrics “randomizer” tool, hence no study personnel were involved in assignment to arms. To avoid enrollment by individuals specifically interested in the study topic, our invitation summary text was vague (“We are interested in understanding how people perceive and think about messages”). Initial analyses were completed by a statistician (LGA) who was blinded to the meaning of the arm variable.