Table 1.

Coding scheme

Theme	Code	Definition & example
Knowledge	Familiarity	Acquaintance with the concept of nudging.
		E.g., [“The topic that I would like to talk about is nudging. Have you ever heard of nudging?”] “I have never heard of it.”
	Observed Nudges	Examples of nudges.
		E.g., “There are these signs, neon signs, an electronic sign that shows you a sad face when you’re going above the speed limit or a nice smiley if you’re ok.”
	Novel ideas	Suggestions for domains for new nudges.
		E.g., “I think walking more around London is a good way. I know they encouraged more cycling but I think people should walk more.”
Individual differences	Objective	Differences in peoples’ motives.
		E.g., “I think of people are willing to do the right thing and willing to be healthy, I think…..”
	Indifference	Lack of interest in target behavior.
		E.g., “There are a lot of people who care about it but you get certain people who don’t. They just do it because they just can’t be bothered to put it into the other bags.”
Self-target	Approval	Level of agreement with being nudged for the self.
		E.g., [“Would you appreciate it if you were nudged into healthy eating?”]
		“Yes. I would appreciate it. I think everyone wants to do it and it is great to be encouraged to do it.”
	Effectiveness	Judgment of the extent that nudging would be successful when targeted at the interviewee.
		E.g., “Personally I don’t think I need any nudges but I guess it helps, yes. I am generally quite healthy anyway.”
General - target	General Approval	Level of agreement with nudging targeted at anyone
		E.g., “I think the food is an absolutely brilliant idea, absolutely brilliant because we have got so much obesity and it is too easy for them to go and grab a big plate, fill it up and then just go back again but if you have got something smaller then you can only eat what is on the plate if you like and I think that is a good thing. I think that would help a lot of people. The stairs is good too because it makes it fun because sometimes exercise can be so boring.”
	General Effectiveness	Judgment of the extent that nudging would be successful when targeted at anyone.
		E.g., “No, what I am saying is, it has its benefits so people who alright yeah, who go to the supermarket and take the back and read it looking at the calories because they are health-conscious but for those that are not they can see a healthy food and just pass it back. So being there means nothing to somebody who has no idea.”
	Specific target groups	Potential population segments targeted by nudges.
		E.g., “So yeah, I think it would be important and from a children’s perspective as well because in supermarkets sweets are deliberately put by the checkout in order for a child to spot them and also last minute shopping so it is all psychological.”
Origin	Actors	Individuals or groups implementing or designing nudges.
		E.g., [“Would it matter for you who is deciding on what is a good behaviour?”] “Probably the dieticians or the doctors.”
	Expertise	Required level of knowledge in the targeted behavior.
		E.g., “Someone who, maybe a nutritionist or something like that because they obviously knows about health things or someone who has done psychology as well and knows why people are going to pick things. Perhaps a psychologist and a nutritionist.”
	Intention	Motives of the agents involved in designing nudges.
		E.g., [“Does it matter who implements these health nudges or who decides on what the good behaviour is?”] “It doesn't matter as long as the goal is clear that it is to help people lead healthier lives.”
	Trust	Degree of confidence in agents’ motives related to the design of nudges.
		E.g., “I would trust somebody that had done their research and it is maybe Government funded or maybe a Government initiative or a health initiative so something that has got a sort of, a reputable backing.”
Behavior	Habit	People’s routine behaviors.
		E.g., “In retrospect, the nudges then hopefully become part and parcel of your life and your everyday working life or home life.”
	Individual Capacity	People’s extend of influence on their own behavior.
		E.g., “Yes actually yes, because we try to push ourselves but sometimes something else influences it, you know what yeah I am going to do it.”
	Facilitation	Supportive effects of nudges on behavior.
		E.g., “As long as people have opinions but make it easier for them to choose the more healthier option.”
	Social environment	The relationship between people’s behavior and their social surrounding.
		E.g., “It might change you one day to say “Come on, everybody is so I might as well” and it is good for the future.”
Freedom of choice	Coercion	Oppressive influences of nudges on behavior.
		E.g., “What you do is you manipulate their decision making whereby it is them noticing that you are doing it or them not noticing that you are doing it, it doesn’t matter. You just manipulate them to do what you want them to do.”
	Nudging-suitable domains	Appropriateness of behavioral domains for nudging.
		E.g., “I don’t know how you can nudge in those areas because there is so much out there, there’s so much and it is personal choice isn’t it? It is personal belief in terms of religion.”
	Choice-set limitation	Restricting the availability of choices and possible behaviors.
		E.g., “I think alternative options are always good like if you had an alternative option but I don’t think they should take anything that is currently there and then say you can’t have that any more.”
Cognition	Reactance	Counter-reaction to the promoted behavior.
		E.g., “There are people who are set in their ways and bringing in anything that is going to be far from their norm, even if it is a simple task, is not going to go down well with them and there are those people who just don’t like change. Even if you bring it, you might want to resist.”
	Awareness	(No) Realization of the influence of nudges.
		E.g., “I think we are nudged every day in life and we don’t realise we are being nudged.”
	Need for information	Required level of information on being nudged and/or the targeted behaviors.
		E.g., “Because they are trying to encourage healthy eating and it is educating people because information is power. If you know the good and the bad things, I hope there are going to be loads of advertisements about these things because people need to be educated and they need to be aware of things before they can be applied in practice.”