Table 1.

List each message used and the associated BCTs.

Number	Screen message	BCT
Baseline	Hand sanitizer	Baseline
1	Be safe. Sanitize your hands.	Action planning
2	You must sanitize your hands.	Action planning
3	You should sanitize your hands.	Action planning
4	You can sanitize your hands.	Action planning
5	Please sanitize your hands.	Action planning
6	Most shoppers sanitize their hands.	Social comparison
7	Our shoppers sanitize their hands.	Social comparison
8	Usually our shoppers sanitize their hands.	Social comparison
9	Our shoppers usually sanitize their hands.	Social comparison
10	Washing hands with sanitizer avoids spread of COVID-19.	Information about health consequences
11	Washing hands with sanitizer can prevent the transmission of COVID-19.	Information about health consequences
12	Washing hands with sanitizer will prevent the transmission of COVID-19.	Information about health consequences
13	Clean hands prevent the spread of COVID-19.	Information about health consequences
14	Hand sanitizer: where have your hands been today?	Information about health consequences

Messages were randomly displayed from the message database.