The TPB states that intention to reduce SSB consumption is an individual level outcome predicting actual reduction of SSB consumption. We will measure intention to reduce SSB consumption as a single, 5-point Likert item with responses ranging from Strongly Agree=5 to Strongly Disagree=1 as follows: "I plan to reduce my consumption of sugary beverages over the next 3 months." Greater scores on this scale represented greater levels of intention to reduce SSB consumption.

We will measure SSB related media literacy using a 5-point, 8-item Likert scale with responses ranging from Strongly Agree=5 to Strongly Disagree=1 adapted from Chen et. al.(Cronbach's Alpha = 0.83). This scale measures how much the participants understand the ways in which SSB industry used media to influence and manipulate their SSB consumption behaviors. Some sample items are as follows: "Certain sugary drink brands are designed to appeal to people like me," "Sugary drink ads show a healthy lifestyle to make people forget about the health risks, such as weight gain and diabetes" and "Sugary drink ads link drinking these beverages to things people want, like love, good looks, and power." Greater scores on this scale represent greater levels of SSB media literacy.

Public health literacy is defined here as an understanding of the social determinants of health. We will measure it using a 5-point and 7-item Likert scale with responses ranging from Strongly Agree=5 to Strongly Disagree=1 (Cronbach's Alpha = 0.78). The seven items measure opinions about how much different external factors affect health because this best reflected an understanding of the social determinants of health: (1) money, (2) education, (3) safe and affordable housing, (4) early childhood experiences, and (5) government policies and programs (6) lifestyle choices and (7) consequences of system failure on the under-resourced. Greater scores on this scale represented greater levels of public health literacy.

Empowerment is defined as a social level construct measured using a 4-point and 8 item Likert scale adapted from Zimmerman et. al. with responses ranging from Strongly Agree/Very Effective=4 to Strongly Disagree/Not Effective at all=1. The scale comprised three subscales namely (1) Community control (2 items; Cronbach's Alpha = 0.68); (2) Perceived effectiveness of actions to influence community decisions (3 items; Cronbach's Alpha = 0.79); and (3) Perceived difficulty (3 items, Cronbach's Alpha = 0.78). Sample questions from each subscale were as follows: "I can influence decisions that affect my community," "How effective would it be to attend meetings about some community issue or problem in convincing public officials and institutions to do something?" and "Community problems are often so complicated that even informed people can't figure out what should be done about them." Greater scores on this scale represented greater levels of psychological empowerment.

Identification is measured using a 5-point, 4-item Likert scale adapted from scales by Cohen and Phua (Cronbach's Alpha = 0.84). Greater scores on this scale represent greater degree of identification with the character in the video. Identification with characters also include the perceived similarity with main character in the video, which will be measured using a 5-point, 2-item Likert scale with responses ranging from Strongly Agree=5 to Strongly Disagree=1 adapted from Cohen et. al. (Cronbach's Alpha = 0.93). The two items in the scale are, "I feel the person in the message, and I have many things in common," and "The person in the video and I are similar in many ways." Greater scores represent greater levels of perceived similarity.

We will measure emotional responses to the video using a 11-item, 5-point scale with responses ranging from Not at all=1 to Extremely=5 adapted from Dixon et. al. (Cronbach's Alpha = 0.95). The question stated "We are interested in how this message made you feel. Please indicate the extent to which the message made you feel…" The scale consisted of seven negative emotions viz., Disgusted, Anxious, Ashamed, Fearful, Guilty, Sad and Angry and four positive emotions viz., Proud, Validated, Hopeful and Empathetic. Higher scores on this scale represented more positive emotional response to the video.

Perceived effectiveness of the message is known to affect intention to engage in a given health behavior. Furthermore, some researchers have raised concerns of reactance as a negative consequence of persuasive messages69, 70 while others seem to argue that it does not necessarily affect the efficacy of a message. Therefore, we will measure perceived effectiveness of and reactance to the stimuli as a proxy measure for intention to reduce SSB consumption using a 5-point, 14-item Likert scale with responses ranging from Strongly Agree=5 to Strongly Disagree=1 adapted from Dixon et. al and other prior research. This scale comprised 4 subscales namely (1) Message Acceptance (2 items, Cronbach's Alpha = 0.89); (2) Argument Strength (4 items, Cronbach's Alpha = 0.88); (3) Personalized Perceived Effectiveness (7 items, Cronbach's Alpha = 0.91); and (4) Reactance (1 item). Greater scores on this scale represented greater levels of perceived effectiveness of the message.

We will measure the willingness to disseminate the message by a 10-point Net Promoter Score (NPS) adapted from Alismail et. al (Cronbach's Alpha = 0.87). The item is, "On a scale from 0-10, how likely are you to recommend this message to a friend or family". Greater scores on this scale indicate greater willingness to recommend the message to others.

Engagement with message in this study means engagement with The Bigger Picture Project campaign since the two experimental treatments were all from this campaign. We will measure this outcome by clicking the campaign link for more information in Qualtrics shown on the stimuli display pages with clicked = 1 and did not click = 0.