Exploring the Design of Nudging in Persuasive Technologies – Improving Sleep Hygiene

Hung-Chiao Chen

Master’s Thesis, 30 ECTS Master’s Programme in Cognitive Science, 120 ECTS Spring 2021 Supervisor: Helena Lindgren, Esteban Guerrero Rosero, Lo¨ısVanh´ee Acknowledgement

Special thanks to Lo¨ısVanh´ee,Esteban Guerrero Rosero and Helena Lindgren for leading me through this incredible learning experience. The journey would not have been as fruitful if it was not for the help and support from them. I also want to thank all the participants that took part in this study. They have provided me the most valuable insights and encouragement that made this thesis possible.

2 Abstract

Research on persuasive technologies for promoting healthy behaviours has been surging in recent years, but these technologies have the risk of being perceived as undesirable meddling. The current study puts forward a non-coercive and libertarian paternalistic alternative – the nudge theory. The foundation of the nudge theory is informed by the dual processing theory and can be categorized in two types – Type 1 nudging and Type 2 nudging. As design tools, two Type 1 nudging methods: default setting and manipulation of accessibility; and four Type 2 nudging methods: reminders, prompts, framing and pre- commitment strategies were selected to be featured. Sleep was chosen as the use case for this study, for it is associated with a number of non-communicable diseases yet considerably few studies of persuasive technology are about sleep. Better sleep hygiene is a significant means to improve sleep, therefore used as the design goal. The current study explores possible solutions for persuasive technologies for improving sleep hygiene, and better understand the design potentials and the persuasive characteristics of different types and methods of nudging. The research methodology is informed by scenario-based design. Five (four male and one female) academic professionals with backgrounds in interaction design, human-computer interaction, artificial intelligence and robotics took part in the study. Seven scenarios and thirteen prototypes were created to illustrate the situations and present the possible solutions. Results also showed that Type 1 nudging is considered more convenient and effective. However, the sense of control is better preserved in Type 2 nudging. In regard to nudging methods, default setting is considered as the most effective method under the condition of goal-alignment, but prone to error. Manipulation of accessibility should be designed so that the navigation is intuitive and the integrity of availability should not be damaged. Timing is the most prominent factor for reminders, and the influence of reminders could be reinforced by prioritizing and cross-platform availability. The presence of prompts could be emphasized by purposeful placement, and appropriateness should be considered. The perception of framing is highly subjective, therefore it should be user-tailored and context-aware. The effects of pre- commitment strategies are able to access higher-level motivation, but should be reinforced with other methods. To summarize the design principles, when designing nudges in persuasive technologies, the following factors should be considered: goal alignment, intuitiveness, context awareness, availability and accessing motivation.

Keywords: persuasive technology, the nudge theory, Type 1 nudging, Type 2 nudging, default set- ting, manipulation of accessibility, reminders, prompts, framing, pre-commitment strategies, sleep, sleep hygiene, scenario-based design

3 Sammanfattning

Forskning inom temat persuasive teknologi f¨orh¨alsoinriktade beteenden har ¨okat under den senaste tiden. Dock kan s˚adanateknologier oftast uppfattas som en o¨onskad inblandning i m¨anniskors privata liv. Denna studie f¨oresl˚arett otvingade och libertarianskt paternalistiskt alternativ f¨oratt p˚averka val och beteenden – nudge teorin. Flera tidigare bepr¨ovade designverktyg betonas i denna teori. Nudge teorin har en dual process teoretisk bakgrund och kan delas in i tv˚atyper av nudging — Typ 1 nudg- ing och Typ 2 nudging. Bland Typ 1 verktyg v¨aljs default setting och manipulation of accessibility, och bland Typ 2 metoder v¨aljs reminders, prompts, framing och pre-commitment strategies. I syfte att illustrera detta anv¨andes s¨omn som exempel, d˚adet har l¨ankats till flera icke-smittsamma sjukdomar och f˚astudier har f¨ors¨oktatt unders¨oka motiverande design i relation till s¨omn.B¨attre s¨omnhygien ¨ar ett betydelsefullt verktyg f¨oratt f¨orb¨attras¨omnoch anv¨andesd¨arf¨orsom m˚als¨attning. Denna studie unders¨oker m¨ojligaalternativ f¨orpersuasive teknologi i syfte att f¨orb¨attras¨omn.Dessutom unders¨oktes potentialen av olika typer av persuasive teknologi och metoder f¨ornudging. Den valda metodologi ¨ar en informerad scenariobaserad design. Fem akademiskt anst¨allda,fyra m¨anoch en kvinna, med bak- grund inom interaction design, human-computer interaction, artificial intelligence och robotics, deltog i denna studie. Sju scenarion och tretton prototyper utarbetades f¨oratt illustrera en situation och presentera en m¨ojligl¨osningd¨ars¨omnhygien kunde f¨orb¨attrasigenom persuasive teknologi. Resultaten visade att Typ 1 nudging ans˚agsvara mer l¨ampligtoch effektiv. Emellertid bibeh˚allsk¨anslanav kontroll mer inom Typ 2 nudging. Default setting ans˚agssom mest effektiv inom betingelsen goal alignment, men med risk f¨orbakslag. Manipulation of accessibility b¨ordesignas s˚aatt navigering ¨arintuitiv och att integriteten av tillg¨anglighetinte st¨ors.Tajming ¨arden mest framtr¨adande faktorn f¨orreminders och de- ras p˚averkan skulle kunna framh¨avas igenom prioritering och cross-platform availability. Prompts skulle kunna framh¨avas mer igenom igenomt¨anktplacering d¨arl¨amplighet¨aren drivande faktor. Uppfattnin- gen av framing ¨armycket subjektiv och b¨orvara anpassad till anv¨andaren.Pre-commitment strategier har tillg˚angtill h¨ogremotivation men b¨orf¨orst¨arkas med andra medel. Sammanfattningsvis b¨orf¨oljande faktorer bet¨ankas inom motiverande design: goal alignment, intuitiveness, context awareness, availability och accessing motivation.

Nyckelord: persuasive teknologi, nudge theorin, Typ 1 nudging, Typ 2 nudging, default setting, ma- nipulation of accessibility, reminders, prompts, framing, pre-commitment strategies, s¨omn, s¨omnhygien, scenariobaserad design

4 Exploring the Design of Nudging in Persuasive Technologies – Improving Sleep Hygiene

In the past two decades, there has been an explosion of research on persuasive technologies for healthy behaviours, including physical activity (Lin et al., 2006; Anderson et al., 2007; Vandelanotte et al., 2016), healthy diets (Vandelanotte et al., 2016; Coughlin et al., 2015), weight loss (Pourzanjani et al., 2016; Turner-McGrievy and Tate, 2011), stress management (Sanches et al., 2010; Heber et al., 2016), glycemic control (Liang et al., 2011) and alcohol and smoking cessation (Lehto and Oinas-Kukkonen, 2011). These technologies provide feasible and appropriate means to assist primary care (Glasgow et al., 2004), which can help prevent non-communicable diseases (Vandelanotte et al., 2016; Peiris et al., 2014) and alleviate the financial burdens of healthcare systems (Elbert et al., 2014). Several theories of persuasion are often employed in persuasive health technology design, such as the reinforcement theory (Nakajima and Lehdonvirta, 2013), the elaboration likelihood model (Petty and Bri˜nol,2011), the theory of planned behaviour (Ajzen, 2011), and the social conformity theory (Chiu et al., 2009). However, the moralizing effects of these well-intended persuasive technologies have the risk and tendency to be paternalistic and perceived as undesirable meddling (Verbeek, 2009). Hence, the current study puts forward a liberal, non-coercive alternative – the nudge theory. The nudge theory, or libertarian paternalism, is a behaviour change paradigm that uses indirect sugges- tions, positive reinforcement and takes advantage of judgemental heuristics and cognitive biases (Thaler and Sunstein, 2009). It has been extensively featured in behavioral economics studies (Acquisti, 2009; Tagliabue et al., 2019) sustainable food choices (Bucher et al., 2016; Vandenbroele et al., 2020) and public policies (Hansen and Jespersen, 2013; of Health, 2010). As opposed to the regulatory, paternal- istic and plausibly over-stepping approaches mentioned earlier, the nudge theory provides more gentle, indirect and liberal ways to help people make better choices. Moreover, the majority of technology-based interventions for healthy behaviour change use web-based services, mobile technologies, wearable devices and desktop applications (Orji and Moffatt, 2018). What these interventions have in common is that the interactions rely on single platforms or systems. However, our choices and behaviours are usually affected by multiple factors. To overcome the limitation of using single platforms/systems and create ubiquitous persuasive interactions, we are suggesting an omnipresent approach – incorporating nudges in the design of appliances and electronic devices. Nudging can be categorized in two types – Type 1 and Type 2, and the foundation of this differentiation is derived from the dual processing theory (Hansen, 2016). The theory entails the notion that there are two systems of thought processes – System 1, which is referred to as automatic thinking; and System 2, which is referred to as reflective thinking (Thaler and Sunstein, 2009; Kahneman, 2011). Type 1 nudging uses automatic thinking to influence behaviours, and operates in an associative manner. Whereas Type 2 nudging uses reflective thinking to manipulate choices and behaviours, and takes a deductive route (Hansen and Jespersen, 2013; Thaler and Sunstein, 2009). In terms of the processing systems, there is a fundamental difference between Type 1 and Type 2 nudging. In this study, we want to clarify how each type is used and perceived to better understand the persuasive properties of nudging. Additionally, we are interested in the specific details of the characteristics and application of nudging methods. As design tools, we have selected two Type 1 methods: default setting – predetermining courses of action that take effect if nothing is specified by the decision maker and manipulation of accessibility – to purposefully arrange the environment in favor of certain behaviours; four Type 2 methods: reminders – timely delivered information that encourages certain choices; prompts – environmental cues that serve to overcome error-prone or repetitive behaviours; framing – changing the presentation of a subject matter to influence decisions and pre-commitment strategies – committing people to certain goals and behaviours. By examining the practical aspects of these methods individually, we aim to yield results that can help the designing processes of nudging-based persuasive technologies. As mentioned previously, research in technology-supported behaviour change extends to many healthy behaviours (e.g. physical activity, weight loss, stress management). However, persuasive technologies for improving sleep have been much less explored (Choe, 2011). Sleep is one of the most important behaviours that contributes to our well-being and health (Pilcher et al., 1997; Smaldone et al., 2007). It allows our bodies to repair themselves and our brains to consolidate memories and process informa- tion (Robotham et al., 2011). Studies have shown that sleep related problems can be associated with chronic non-communicable diseases such as depression, cardiovascular diseases, degenerative arthritis, and gallstones (Basnet et al., 2016). Previous research on technologies for sleep interventions focus on using cognitive behaviour therapy for insomnia (CBT-I) (Espie et al., 2001; Kuhn et al., 2016), actig- raphy (Ferguson et al., 2015), sleep tracking (Baron et al., 2018) and relaxation/wellness (Bauer et al., 2012). In contrast to those methods, the current study employs the multi-factor sleep hygiene as design

5 goal. For it provides a more holistic approach, and have been presented as a significant means to improve sleep and sleep quality (Brown et al., 2002; Brick et al., 2010). Considering that the developmental process is still at its early stages, the research methodology of the current study is informed by scenario-based design (Carroll, 1997). Scenario-based design is an activity-oriented (Kuutti and Arvonen, 1992) user-centered technique that uses detailed yet concrete descriptions to capture real-life situations and able to evoke reflection on multiple views in a diverse range of detailing (Kuutti and Arvonen, 1992; Rosson and Carroll, 2009). The current study explores the design potentials and the persuasive characteristics of different types and methods of nudging that may be used in ubiquitous persuasive technologies that encourage or facilitate better sleep hygiene through scenario-based design. The research questions are as follows:

• RQ1: How are the different types of nudging perceived when used in persuasive technologies that promote sleep hygiene?

• RQ2: What design elements should be considered when using nudging methods such as default- setting, manipulation of accessibility, reminders, prompts, framing and pre-commitment strategies when designing persuasive technologies that help improve sleep hygiene?

• RQ3: What are the main concerns when designing nudges in persuasive technologies?

Background

In this section, we introduce the main concepts and theories involved in the current study. In the purpose of better illustrating the research objectives. The content includes: persuasive technology, the nudge theory and sleep hygiene.

Persuasive Technology An Overview The term captology, which is the study of computers as persuasive technologies, was introduced by Brian Jeffrey Fogg (Fogg, 1998, 1999) in the late 90s. Fogg defined persuasive technologies as “interac- tive technologies that shape, reinforce, or change behaviors, feelings, or thoughts about an issue, object, or action (Fogg, 1998)”. Following that, Harri Oinas-Kukkonen and Marja Harjumaa defined persua- sive system as “computerized software or information systems designed to reinforce, change or shape attitudes or behaviors or both without using coercion or deception” (Oinas-Kukkonen and Harjumaa, 2008). Instances of such technology can be found in energy conservation (Emeakaroha et al., 2014), education (Mintz and Aagaard, 2012) and military training (Zyda, 2005). Studies have also indicated persuasive technology as a promising means for promoting health and wellness (Orji and Moffatt, 2018; IJsselsteijn et al., 2006). Nowadays, the majority of persuasive health technologies are web-based or mobile-based (Matthews et al., 2016; Lehto and Oinas-Kukkonen, 2011), utilizing ambient technologies such as desktops, laptops, mobile technologies and internet services to create opportunities for persuasive interactions (Oinas- Kukkonen and Harjumaa, 2009). However, these are by no means the only way persuasive technology can take form (Chow et al., 2017). In addition to mobile-based technology, the current study also discusses the use of internet-of-things(IoTs) and the interaction design of electronic appliances as means for persuasion.

Functional Triad According to Fogg, persuasive technologies can be classified into three categories: tools - technologies that increase capabilities; medium – technologies that provide experiences; and social actors – technolo- gies that create relationships, which form a functional triad (Fogg, 1998). These agents/technologies influence users through mental modeling, promoting understanding and providing social support (Fogg, 2002, 2003).

1. As tools: Technologies that are used as tools serve to increase capabilities and make target behaviour more achievable by reducing barriers, facilitating self-efficacy and providing information. For example, reducing the complexity of tasks to encourage certain behaviours using computing technology – reduction.

6 Figure 1: Functional triad of persuasive technology (Fogg, 2002)

2. As medium: Technologies that function as mediums serve to provide experiences, by supporting first-hand learning, insight and visualization. They allow the exploration of the cause-and-effect relationship between events and activities, and facilitate rehearsals of behaviours. 3. As social actors: Technologies that take the role of social actors serve to create relationships. The persuasive intent is expressed through positive feedback, aiding the modeling and shaping of target attitude or behaviours. They also establish social norms by providing social support or sanction.

The Nudge Theory An Overview The concept of nudging was popularized after the publication of ”Nudge: Improving Decisions About Health, Wealth, and Happiness” by Richard H. Thaler and Cass R. Sunstein (Leonard, 2008). In recent years, it has been presented as a new and ethically justified way of improving people’s health (Vallg˚arda, 2012; Blumenthal-Barby and Burroughs, 2012). Nudging takes advantage of judgemental heuristics and cognitive biases such as rules of thumbs, anchoring, availability, representativeness and status quo bias (Thaler and Sunstein, 2009; Kahneman, 2011). Also, freedom of choice is typically preserved in nudging(Schmidt and Engelen, 2020; Sunstein, 2014). In contrast to the paternalistic approaches in previous studies, this study explores a method that persuades through positive reinforcement and indirect suggestions.

The Two Cognitive Systems In the beginning of their book, Thaler and Sunstein established the two cognitive systems - automatic and reflective thinking (Thaler and Sunstein, 2009) (see Table 1), which distinguishes automatic processes with deliberate choices (Hansen and Jespersen, 2013). This theoretical framework is derived from the works of Daniel Kahneman – the dual processing theory. The dual processing theory provides an account that differentiate thought processes in two systems, with system 1 being intuitive, implicit, rapid, mostly involuntary and uses unconscious reasoning, and system 2 being deliberative, explicit, slow, mostly voluntary and uses conscious thinking (Kahneman, 2011).

Typology and Transparency Nudges can be categorized into two types, and the typology of nudging is based on the differentiation of automatic thinking and reflective thinking or the dual processing theory (Grayot, 2020; Hansen, 2016). Type 1 nudging corresponds with system 1 processing. This type of nudges aim at affecting behaviours by influencing automatic thinking. These nudges work in a more effortless, unconscious and associative manner. Whereas Type 2 nudging corresponds with system 2 processing, it aims at influencing behaviours and choices by manipulating reflective thinking and redirecting attention . This type of nudges work in a more effortful, deductive and deliberative manner. (Groves and Thompson, 1970; Evans, 2008; Thaler and Sunstein, 2009; Hansen and Jespersen, 2013).

7 Table 1: Two cognitive systems (Thaler and Sunstein, 2009) Automatic system Reflective system Uncontrolled Controlled Effortless Effortful Associative Deductive Fast Slow Unconscious Self-aware Skilled Rule-following

The nature of the nudges can also differ in transparency. The transparency in the nudge theory refers to the disclosure of intentions, or the lack of, to decision makers (Wachner et al., 2020). The legitimacy and ethics of non-disclosed or nontransparent nudges have been questioned, for the reason that behaviours and choices may be unknowingly influenced (Hansen and Jespersen, 2013). However, Thaler and Sunstein argued that nudging is an admissible approach to behaviour change in public policy making (Thaler and Sunstein, 2009)”. Since there are many other more intrusive and/or subtle measures (e.g.taxation and marketing strategies) that are influencing and manipulating our decision making and still retained their legitimacy (Hansen and Jespersen, 2013). Applying nudges in public policies should be deemed as a permissible and justifiable approach. With the differentiation of the typology and transparency, a grid can be formed (see Figure 2), with each quadrant representing a category of nudging: Type 1 transparent, Type 1 non-transparent, Type 2 transparent and Type 2 non-transparent.

Figure 2: Four categories of nudges (Hansen and Jespersen, 2013)

1. Type 1 transparent nudging is the transparent influence of behaviour. This category of nudges target automatic thinking and affect unconscious behaviours. The intentions of these nudges are disclosed and explicitly displayed. Some examples of Type 1 transparent nudges are: explicit defaults, explicit visual illusions and speed bumps. 2. Type 1 non-transparent nudging is the manipulation of behaviour. This category of nudges also target automatic thinking and affect unconscious behaviours. However they are more intrusive than Type 1 transparent nudges, as the intentions of these nudges are implicit. The influences of these nudges usually go undetected and are hard for individuals to avoid. Some examples of Type 1 non-transparent nudges are: implicit defaults and product arrangements in supermarkets.

8 3. Type 2 transparent nudging is the facilitation of choice. This category of nudges target au- tomatic thinking and affect conscious choices. Type 2 transparent nudges are the least invasive nudges. They enable individuals to freely make decisions by directing their attention to behaviours or the consequences of those behaviours that align with the intentions behind these nudges. Some examples of Type 2 transparent nudges are: reminders, prompts, feedback and pre-commitment strategies. 4. Type 2 non-transparent nudging is the manipulation of choice. This category of nudges also target automatic thinking and affect conscious choices. However, Type 2 non-transparent nudges influence choices by unconsciously manipulating the reflective thinking process. Like Type 1 non- transparent nudges the effects of these nudges on individuals are usually not recognized. Some examples of Type 2 non-transparent nudges are: framing, priming and lottery incentives. (Hansen and Jespersen, 2013; M¨ollenkamp et al., 2019)

Heuristics and Cognitive Biases The concept of heuristics was originated by Herbert A. Simon (Simon, 1955), but it was Daniel Kah- neman and Amos Tversky that brought it to the forefront in the 70s and 80s. Heuristics are mental short-cuts or strategies derived from previous experiences that people use to simplify the process of deci- sion making or problem solving (Gigerenzer and Gaissmaier, 2011; Simon and Newell, 1958). They help save time on reasoning and can yield quite acceptable results in regular day-to-day situations. However, occasionally these decision-making shows systematic simplification and deviation from rationality, which lead to sub-optimal outcomes – cognitive biases (Korteling et al., 2018). Nudging methods take advantage of judgemental heuristics and cognitive biases by engineering the choice architecture in favor of desirable outcomes (Campbell-Arvai et al., 2014). Three judgement heuris- tics were proposed by Kahneman and Tversky, including representativeness, availability and adjustment & anchoring (Tversky and Kahneman, 1974).

1. Representativeness: The represnetativeness heuristic is a mental short-cut where individuals use the most prominent mental prototype or stereotype for comparison. It is the tendency to decide or make judgement on the frequency or likelihood of an event by how similar it is to the mental prototype (Kahneman and Tversky, 1972; Dale, 2015). An example of this heuristic is systemic racism. The law enforcement in America has a lower bar for searching black and Hispanic drivers compared to white drivers (Pierson et al., 2020). 2. Availability: The availability heuristic is a decision-making strategy where individuals make decisions based on knowledge that is readily available, instead of researching the alternatives. It is the tendency to make judgements or form opinions about something according to more recent information. For example, one might think that traveling with a car is safer than traveling with a plane, because the information on plane crashes is more available to them. When in fact, the odds are that one has a higher probability to die from a car crash than an aviation accident. 3. Anchoring & adjustment: The anchoring heuristic is the tendency to make judgement according to a reference point or “anchor”, and that individuals are sometimes disproportionately influenced by the initial information entry (Dale, 2015; Tversky and Kahneman, 1974; Chapman and Johnson, 1994). After the value of the anchor is set, the assessments or estimation that come after uses that value as a reference. This heuristic is often used in retail or real estate negotiations. For example, the asking price of a real estate property is often set higher than the expected selling price.

Two cognitive biases are often exploited when using nudging methods: status quo bias and framing effect.

1. Status quo bias: The status quo bias is the preference of remaining in the current state of affairs and avoid change, even when the current state may not be objectively superior, as changes are often perceived as loss or detriment. It is a non-rational cognitive process and one of the implications of loss aversion (Kahneman et al., 1991), which is the tendency to avoid losses instead of acquiring gains similar value (Tversky and Kahneman, 1992). For example, during elections, the incumbents have an advantage to win than the challengers (Gelman and King, 1990). 2. Framing effect: The framing effect is a cognitive bias where an individual’s decisions is based on the presentation of the information. The positive or negative connotations are associated with loss or gain. People have a tendency to avoid risk when a piece of information is framed positively, and

9 seek risk when it is framed negatively (Tversky and Kahneman, 1981). For example, consumers are more likely to choose a meat product with a nutrition label of 75% lean instead of 25% fat (Levin and Gaeth, 1988).

Nudging Methods There are a plethora of methods one could design nudges with. The current study will mainly feature the following 6 methods: default setting, manipulation of accessibility, reminders, prompts, framing and pre-commitment strategies. The first two methods are categorized as Type 1 nudging and the rest is Type 2. 1. Default setting is the most effective way of nudging (Sunstein, 2014). It is to predetermine courses of action that take effect if nothing is specified by the decision maker (Thaler and Sunstein, 2009). It makes use of decision-making cognitive biases such as status quo bis, aversion and the endowment effect (Kahneman et al., 1991; Knetsch, 1989). Some examples of this method of nudging are: automatic enrollment in educational systems, and organ donation (Thaler and Sunstein, 2009). 2. Manipulation of accessibility is to purposefully arrange the environment and surroundings in favor of certain behaviours. This method was mentioned at the opening of the introduction in Thaler and Sunstein’s book (Thaler and Sunstein, 2009). Where a school system’s director of food service found out that they could change the consumption of certain food items by arranging them differently, without changing the menu. Other examples of this nudging method are product arrangements in supermarkets (Van Gestel et al., 2018) and renewable energy options (Pichert and Katsikopoulos, 2008).

3. Reminders serve to encourage or facilitate choices through directing individuals’ attention and nudging them into action or decision (Kwan et al., 2020). Many reasons could cause the non- action of goal behaviours. For example: inertia, procrastination, competing obligations, and simple forgetfulness (Sunstein, 2014). Reminders are set out to help overcome these hindrances. One very important factor for a reminder is timing. It is empirical to make certain that individuals take action upon the delivery of the information. Some examples of this method of nudging are text messages (Castleman and Page, 2015) and mobile phone notifications. 4. Prompts are changes to the physical environment such as signs or stickers that aim to elicit reflective thinking and overcome error-prone or repetitive behaviours (Lehner et al., 2016). They are usually designed to guide a choice of interest by establish a standard of behaviour or present an ideal alternative (Soler et al., 2010) Prompts are widely used in local energy saving campaigns (Staddon et al., 2016), and encouraging stair use (Soler et al., 2010; Andersen et al., 1998). 5. Framing is to change the presentation or phrasing of a subject matter in the purpose of influencing individuals’ choice (Thaler and Sunstein, 2009). It utilizes the cognitive bias where individuals base their decision on whether the connotations of the options presented positively or negatively (Plous, 1993). When an option is positively framed, decisions are more likely to lean toward risk avoidance. And when negatively framed, decisions are more likely to be skewed toward risk seeking (Tversky and Kahneman, 1981,?). 6. Pre-commitment strategies serve to commit people to certain behaviours, as most of them seek to be consistent with promises (Sunstein, 2014; Vlaev et al., 2016). It is the least effective method of nudging (Hummel and Maedche, 2019), but it helps identifying goal behaviours and supports the definition of a clearer pathway. Pre-commitment strategies can be found in the promotion of healthier food choices (Cohen et al., 2015) and encouraging voter turnout (Nickerson and Rogers, 2010).

Sleep Hygiene Sleep hygiene is a set of behavioural and environmental recommendation for promoting healthy sleep (Irish et al., 2015). It was originally developed for the treatment of mild to moderate insom- nia (Hauri, 1977; Irish et al., 2015). Now it is mainly used as advice for promoting healthy sleep and research purposes.

10 The Recommendations of Sleep Hygiene 1. Keeping a regular sleep/wake cycle: Maintaining a consistent sleep schedule helps the internal circadian rhythm run smoothly (Hauri, 1977). It is also suggested that one should go to bed and wake up at the same time even on weekends. 2. Physical activity: Regular exercise can make it easier to fall asleep and deepens people’s sleep at night in a long-term perspective (Hauri, 1977). However, strenuous exercises should be avoided late in the evenings. 3. Limiting compensatory sleep: Naps are helpful for boosting energy and cognitive functions, but long naps (over 30 minutes) and naps late in the afternoon can make falling asleep difficult. 4. Be mindful of caffeine intake: Caffeine is the most widely consumed stimulant in the world (Ra- makrishnan et al., 2016),. However caffeine merely restores performance degraded by sleepiness during the day and can have a disruptive effect on sleep (Roehrs and Roth, 2008). In addition to trouble falling asleep, one study also found that caffeine can delay the timing of your circadian rhythm. Therefore, it is suggested that caffeinated beverages should be avoided at least eight hours before bedtime, and one should be mindful of the amount of caffeine consumed during the day. 5. Be mindful of alcohol intake: Sleep onset may be facilitated by alcohol consumption, as a con- sequence of its sedative properties. However, the metabolizing process may cause sleep disruption and sleep fragmentation later into the night (Ebrahim et al., 2013).

6. Light exposure: Natural daylight is the most important external factor to sleep and the key driver for circadian rhythms. One should be exposed to natural daylight for at least 30 minutes each day. However, bright light in the evening can hinder the production of melatonin, a hormone that the body creates to facilitate sleep. Therefore, excessive light exposure should be avoided in the evening and the bedroom should be pitch dark when sleeping (Dumont and Beaulieu, 2007; Ancoli-Israel et al., 2003). 7. Establish good association between the bed/bedroom and sleep: It is important to link the mind between the bed and sleep. It is suggested that the bed should only be used for sleep and sex. When experiencing difficulty falling asleep, don’t toss and turn, associating anxiety and restlessness to sleep may lead to more severe insomnia. Bed restriction is proven to help sustained sleep improvement and depth (Hoch et al., 2001).

Sleep Hygiene and Zeitgeber One major concept in chronobiology that is associated with circadian rhythms is “Zeitgeber” (Aschoff and Pohl, 1978). Zeitgeber is a German word that literally translates into “time giver”. It is an um- brella term for environmental time cues that help trigger an organism to the entrainment of a 24-hour cycle (Dimitriu and Barkoukis, 2007). The most influential zeitgeber is light (M¨unch and Bromundt, 2012). So much so that light is used in treatments for misaligned circadian rhythm sleep disorders such as delayed and advanced sleep phase syndrome (Arendt, 2010; Gooley, 2008). Other zeitgebers also include temperature (Rensing and Ruoff, 2002), food (Lewis et al., 2020), exercise (Edwards et al., 2009; Lewis et al., 2018) and melatonin (Gnocchi and Bruscalupi, 2017; Rawashdeh and Maronde, 2012).

Scenario-Based Design Scenario-based design is an activity-oriented (Kuutti and Arvonen, 1992) user-centered technique that uses concrete description of a future system to help us understand and create systems and applications during the developmental process (Rosson and Carroll, 2009). The method was originally developed and used in the field of software development (Rosson and Carroll, 2002; Leinonen et al., 2008). Now it can also be found in research in explainable AI (Wolf, 2019), multi-agent systems (Moulin and Brassard, 1995) and even architecture (Van der Linden et al., 2019; L¨uleyet al., 2019). The use of scenarios has gained recognition in both research and practice as a means to ground the developmental process on users (Hertzum, 2003). Detailed narrations of system operation and user interactions are used in the early stages of development to inform the design process (Rosson and Carroll, 2009). The tasked-based and descriptive characteristics of this method allows developers to address multiple objectives and capture real-life context (Hertzum, 2003).

11 Scenario-based design addresses five challenges in information technology development: (1) it gives rise to context-based reflection that can assist the coordination between action and reflection; (2) scenar- ios are definite in description yet flexible in nature, which help developers navigate the fluidity of design situations; (3) scenarios are capable of carrying multiple perspectives and diverse levels of detailing, which help developers gain insight on the consequences of design moves; (4) the abstraction and catego- rization of scenarios allows developers to recognize, capture and reuse generalizations; (5) scenario-based design can facilitate communication among stakeholders, which helps increase the accessibility to a more diverse perspective and address external constraints (Carrol, 1999).

Figure 3: 5 reasons for scenario-based design(Carrol, 1999)

Method

Research Methodology Given the hypothetical nature and the number of target behaviours and subsequent situations, the research methodology is informed by scenario-based design. The use of scenarios allows the explorations of designs of different affordances and evoke reflection on various nudging types, methods and the po- tential interactions with them. It also helps take the fluidity of the design situations into consideration, thus allowing flexible and responsive discussions about design moves. The participants of the current study are academic professionals in the fields of interaction design, artificial intelligence, human-computer interaction and robotics. Moreover, some of the participants have expertise in nudge theory and persuasive technology. Which helps the discussion to be informed by a variety of perspectives on a professional level. Demonstrations are presented during the interviews with visualization of the conceptual prototypes. This aids participants to better understand the designs and invoke reflections, thereby facilitating effective communications.

Research Design To understand the design potentials of different types and methods of nudges, and how they can be applied in persuasive technologies that promote sleep hygiene. Participants with professional back- grounds in related fields were invited to scenario-based design interviews to provide insight from experts’ perspectives. Qualitative data were obtained from the interviews and analysed with thematic analysis. The interviews were performed one-on-one over Zoom. Participants were asked to assess, evaluate and comment on the prototypes that are presented within the respected scenarios. 7 scenarios with 13 prototypes were presented to the participants throughout the interviews. The discussions mainly focused on the types and methods of nudges and how they should be designed. The scenarios and prototypes were created to address decisions that may impact sleep in a daily routine along with the following sleep hygiene recommendation: increasing natural daylight exposure, physical activity mindful of caffeine intake, decrease light exposure in the evenings, relaxation activi- ties, keep a nightly routine and regular sleep patterns. The items of sleep hygiene were selected from

12 literature (Posner and Gehrman, 2011; Mindell and Owens, 2015) and the sleep foundation’s official website (Irish et al., 2015; Zandy et al., 2020; Hossein Koulivand et al., 2013). Six nudging methods are featured by the prototypes: default settings, manipulation of accessibility, reminders, prompts, fram- ing and precommitment strategies. As a matter of illustrating these scenarios, we introduce a fictional character – William, a male high school math teacher.

Participants A total of five participants (four males, one female) took part in this study, they were recruited individually via email. The participants are academic professionals with backgrounds in interaction design, human-computer interaction, artificial intelligence and robotics. All participants have at least a doctoral degree or are currently working in a doctoral position.

Procedure Setup All the interviews were carried out online via Zoom. Participants were given a link prior to the interview sessions. During the interviews, participants were presented with the material with Google Slides and given a digital handout. The sessions were audio recorded with Open Broadcaster Software (OBS), and transcribed afterward.

Introduction Each session began with an introduction. Which starts with some background questions and the debriefing of the overall procedure and research objectives. This is followed by a brief presentation of the nudge theory and sleep hygiene. The reason for the presentation is to ensure each participant had sufficient background knowledge to proceed to the following parts. The presentation included an overall summary of the nudge theory, typology and the six nudging methods featured in the current study and the sleep hygiene items.

Interview For the main interview, participants were given descriptions of scenarios and then presented with the prototype(s). After explaining the designs of the prototype(s), participants were asked to discuss them in terms of the nudging methods and types and provide feedback and suggestions for improvements about the prototypes. The scenario descriptions were presented in short texts and images (see Material).

Analysis Qualitative data was collected through remote individual interviews and analysed with thematic analysis. The data is first analysed with closed-coding, to gather information on each type and method individually. Then an open-coding process was applied to identify patterns and related concepts. Each nudging method was discussed separately in terms of its practical usage in scenarios. And the persuasive properties of the methods were investigated collectively, as Type 1 and Type 2 nudging. Finally, design principles for nudges in persuasive technologies were summarized from the results.

Material

Scenario 1 – Rise and Shine It’s 7:05 in the morning, William has just been woken up by the alarm. He usually stays in bed to check his phone for about 5 8 minutes after waking up. As he is scrolling through his notifications, here comes a new one. It says... In the Rise and Shine scenario, the user has just woken up. By detecting the sounds in the room and activities on the phone, the mobile-technology-based application determines that the user is awake. On the curtains’ side, the device also detects that the curtains have not been opened. A confirmation dialog is then delivered to the user. The confirmation dialog consists of a text and two buttons (see Figure 4). The confirm button (“Yes”) would activate a device that opens the curtains, and the cancel button (“Not now”) would delay the action.

13 Figure 4: Rise and shine notification

This prototype serves to encourage and facilitate natural daylight exposure in the morning. It features an IoT system that can detect the wakefulness of the user and their actions (or non-action). It also delivers a confirmation dialog that not only aims at drawing attention to the dialog message, but also facilitates the execution of the behaviour with a click of a button. Two nudging methods are present in this prototype. Reminder – the notification that is delivered to the phone. And manipulation of accessibility, which is the call to action button that provides access to the curtain-opening device.

Scenario 2 – Step Tracker It’s 2 PM, William is sitting at his desk, grading papers. The phone on the desk buzzes, here comes another notification. It is from his step- tracking app. He downloaded the app 3 weeks ago and had set the goal to walk 10,000 steps a day. The notification says...

Figure 5: Step tracker notification

In the Step Tracker scenario, the user had previously downloaded a fitness app that calculates steps, and made a goal of achieving 10,000 steps every day. The system monitors the user’s position and movement, and has detected that the user has been in the same position and the step-count has come to a halt for a longer period of time. Therefore, the system delivers a notification stating how many steps the users have accumulated so far and how many steps until the user’s daily goal is reached (see Figure 5). This prototype is a pedometer facilitated mobile application that detects movements and track steps, and delivers notifications according to its analysis of the collected data. This feature serves to encourage physical activity. Two nudging methods are present in this feature. Reminder – the notification that is delivered to the phone. And pre-commitment strategies – having the users set a daily goal.

Scenario 3 – The Coffee Machine It’s 3 PM now, William has been working all day. It’s time for a fika. He walks to the teachers’ lounge and goes up to the coffee machine to make himself a coffee. On the touch screen he sees.... In The Coffee Machine scenario, the user intends to have a cup of coffee in the afternoon. Two prototypes of the coffee machine touch screen interface can be found in this scenario. For the first coffee machine, the user is first presented with an interface that shows only a decaf and a skip button, which requires a decision/command before moving on to the main interface where the user can select the type of coffee. For the second coffee machine, the user would see a prompt in the right under the main screen and above the decaf button. The prompt would state ”Decaf option available” (see Figure 6). Both prototypes serve to encourage users to limit caffeine intake and to switch to decaf options. The first coffee machine uses the method manipulation of accessibility. By inserting a “checkpoint” in the

14 Figure 6: Two coffee machine designs

process that requires the user to choose whether to make the coffee decaf or skip and have a regular one, it creates a shift in the choice architecture that aims at increasing the adoption rate of the decaf option. The second coffee machine uses a prompt. A simple text that changes the physical environment for the purpose of directing users’ attention to the given message and elicit reflective thinking about caffeine intake.

Scenario 4 – Night Light It’s 6 PM now, after a long day at the school, William finally made his way home. He opens the front door, the apartment is completely dark. So he reaches for the switch and...

Figure 7: Two light switch designs

In the Night Light scenario, the user enters an indoor space in the evening, and the room requires lighting. Two prototypes of the light switch can be found in this scenario. For the first light switch, the lighting is set at a “night mode” setting. When the user turns on the light, the brightness is lowered and the color is adjusted to a warmer tone. The user could flip the switch again to revert it to the regular setting. For the second light switch, the user would see two switches. The switch on the right is the regular one and the switch on the left would allow access to the “night mode” setting (see Figure 7). Both prototypes aim at facilitating and encouraging the habit of using a “night-mode” setting for room lighting late in the day. The purpose is to decrease light exposure in the evening. The first light switch uses the method default setting. As the night-mode setting is predetermined, the user would automatically have the room lighting set at night-mode. Unless the user specifies otherwise - flipping the switch again. The second light switch uses the methods manipulation of accessibility and prompt. The night-mode switch next to the regular one creates an easy access to the target environmental setting. And the icon/graphical prompt serves to invoke reflective thinking by presenting a cue that can be associated with nighttime.

Scenario 5 – Display Brightness It’s 8 PM now. William has had dinner already and has been resting on the sofa. He remembers that there is still some preparation work for tomorrow’s lecture. He takes out the laptop and...

15 Figure 8: Two screen brightness designs

In the Display Brightness scenario, the user intends to use the laptop in the evening. Two prototypes of the display setting can be found in this scenario. For the first display, the night-light mode is set as default. The laptop would switch to the night-light mode after 6 PM automatically. For the second display, a graphical icon button (see Figure 8) with a caption “Night Light” would appear in the corner of the screen. By clicking on the button, the night-light mode would be activated. The prototypes in this scenario are similar to the ones in the previous scenario, but they differ in context. The purpose of the two prototypes in this scenario is also todecrease light exposure in the evening. However, in this scenario, the light source is the laptop’s screen instead of the room lighting. Moreover, the user is engaging with the prototypes with different intentions and performing different tasks. Thus creating interaction dynamics that separate scenario 5 and scenario 4. The first display setting uses the method default setting, the display would automatically have the night-light mode activated at a designated time point. The second display setting uses the methods manipulation of accessibility, reminder and prompt. The icon button alters the accessibility of the night-light activation. And the graphical aspect of it acts as a reminder/prompt that serves to invoke reflective thinking by presenting a cue that can be associated with nighttime.

Scenario 6 – Meditation It’s 9:30 PM now, William has been on the sofa watching Netflix since he finished working. An icon appears at the corner of the screen - it is from a meditation app. He downloaded the app two weeks ago and had set the goal to meditate for 15 minutes every night. There is also a notification on his mobile phone. The notification says...

Figure 9: Meditation app notification

In the Meditation scenario, the user had previously downloaded a mobile meditation app and made the commitment to meditate 15 minutes every night. As the current time is approaching the scheduled daily meditation; notifications were delivered to two separate platforms. A graphical icon shows up at the corner of the TV screen, and a push notification with texts shows up on the user’s mobile phone (see figure 9). The prototypes in this scenario serve to encourage the user to maintain a habit of meditation every night. The purpose is to enforce the practicing of relaxation activities and aiding the user to keep a nightly routine.A pre-commitment strategy is used to set a daily goal for the user. The graphical icon uses the method reminder and prompt, and the text-based push notification uses both reminder and framing. Considering the nature of the context - late at night, the reminder is delivered across multiple platforms to ensure that the user does not miss it.

16 Scenario 7 – Set the Alarm It’s 10:30 PM now, William is feeling quite tired after a long day. He is ready to go to bed. He sits down at the edge of the bed and turns on his phone to set an alarm. As he clicks open the app he sees...

Figure 10: Three alarm setting designs

In the Set the Alarm scenario, the user is about to go to bed and is setting the alarm. Three prototypes can be found in this scenario. For the first alarm, a confirmation dialog is delivered once the alarm app is opened. The confirmation dialog consists of a text and two buttons (see Figure 10). Clicking the confirm button (“Accept”) would result in setting the alarm at the ideal time - 7AM. Clicking the cancel button (“Decline”) would delay the action. The second alarm, the target wake-time is highlighted with a different color. The last prototype allows the user to set the alarm at the same time everyday at once. All the designs serve to encourage regular sleep patterns. The first alarm uses the methods reminders and manipulation of accessibility. By delivering a confirmation dialog with a confirm button that acts as a shortcut, the design redirects the users attention and creates an easier access to goal behaviour. The second alarm uses the method prompts, in a colour-schematic manner. By highlighting the target option, this design aims at making the target option the most obvious one. The last alarm uses the methods pre-commitment strategies and default setting, users are able to commit to a regular wake-up time by setting a default alarm.

Results

Nudging Types This section addresses RQ1 – How are the different types of nudging perceived when used in persuasive technologies that promote sleep hygiene?

Type 1 Nudging Type 1 nudging was generally well received for its convenience and effectiveness. Participants ex- pressed that it requires less cognitive resources for the users to make the “right” choice, or behave “correctly”. It is mainly contributed by the fact that default setting predetermines courses of actions; and manipulation of accessibility arranges the environment in ways that either the ideal choice is the obvious one or goal behaviours are made easier to achieve.

“It (Default setting) doesn’t require me to make any choices, it just automatically takes care of it. It relieves the burden of me having to make the same decision over and over again.” – Participant A

However, it was believed that these advantages only exist under the condition of goal alignment. It is important to make sure that the goals of the system are oriented to the ones of the users. When the goals are misaligned, error arises and may cause frustration. On the other hand, when goals are aligned, some participants even suggested that the nudges could be more aggressive. For example, in the scenario “Rise and Shine”, 3 participants actually said that opening the curtain should be set as default if it suits the user’s need.

17 “If opening the curtains is what the user wants, then I think this nudge can go even further and just automatically open them. In this case, it would make sense to just use a default setting, instead of asking the user every morning.” – Participant D

Another concern about Type 1 nudging was raised in regard to explainability. With methods such as default setting and manipulating accessibility, the intent, reasoning, and decision-making processes are sometimes not explicitly displayed. This may result in distrust in the systems. On the other hand, some argued that explainability is not necessary in every instance. If the system has justifiable beliefs that the actions are indisputable and beneficial, e.g. setting night light as display default in the evenings, the lack of explainability could be overlooked.

“The problem with display setting 1 is explainability. It is not particu- larly invasive, it doesn’t invade your personal freedom or privacy. I just wouldn’t exactly know why the system does what it does.” – Participant D

Type 2 Nudging The sense of control is better preserved in Type 2 nudging, and was considered less invasive than Type 1 nudging. Participants believed that this is due to the fact that Type 2 nudging operates in ways that do not reach over the barrier and change the settings or the environments. Instead, it facilitates or manipulates choices through directing users’ attention and evoking reflection. Users generally would have more control over whether to take action or not, therefore it is perceived as less invasive than Type 1 nudging.

“Notifications are good in the sense that they only serve to remind us what we are supposed to do. Whether we do it or not, that’s totally up to ourselves.” – Participant D

According to the participants, Type 2 nudging has a stronger correspondence with higher level mo- tivations, on account of the processing system Type 2 nudging utilizes, which is the system 2 reflective thinking. They indicated that by evoking reflection on the “why” behind the decisions, this type of nudging extends its influence beyond conditions and goals to motivation.

“The user is no longer just thinking about the immediate goal here. A higher level of motivation is involved when they start thinking about why they are doing these things.” – Participant E

However, participants were concerned that Type 2 nudging is prone to be ignored, because the effects are limited by attention. Especially nowadays, where there are countless instances that are competing for people’s attention. One phenomenon that illustrates this problem was discussed during an interview – inattentional blindness or perceptual blindness. For example, in the Coffee Machine scenario, if the user was preoccupied or their visual search was solely fixated on certain keywords (i.e. beverage names), they are likely to overlook the prompt in the second coffee machine (see Figure 6).

“One thing about reminders is that they are often just pop-up notifica- tions and messages. A lot of people don’t really look at them, many are just swiped through or are deleted before even being read.” – Participant B

Nudging Methods This section addresses RQ2 and RQ3 – What design elements should be considered when using nudging methods such as default-setting, manipulation of accessibility, reminders, prompts, framing

18 and pre-commitment strategies when designing persuasive technologies that help improve sleep hygiene? What are the main concerns when designing nudges in persuasive technologies?

Default Setting Default setting was perceived as the most effective and convenient. Nevertheless, it is thought to be more prone to error than other nudging methods, specifically when the goals of the system and the user are misaligned. Participants suggested that when designing default settings in persuasive technologies, the designer should make sure that goal alignment is ensured or that there is a justified belief that the actions are in the user’s best interest. Additionally, opting out of the setting should be available and accessible. For example, in the Night Light scenario, the default setting in the first light switch can be easily modified (i.e. double flip). Another suggested approach to address this concern is to have an opt-in mechanism for the default setting. Allowing the users to specify the setting to their liking. In cases where users may be impartial to the options, designers could take advantage of the status quo bias and make the default setting as users’ reference point. Namely, introduce the users with the preferred setting, and let the inertia take its course.

“Sometimes it’s easier to just set it(display brightness) as a default. I think many people would just take it as it is.” – Participant B

Manipulation of Accessibility Manipulation of accessibility was considered to be the “smarter” approach, for the reason that simply by rearranging the physical environment, the choice architecture could be modeled in favor of certain behaviours. Intuitiveness is thought to be imperative when designing nudges with this method, since it utilizes automatic thinking. For example, in the rise and shine scenario, the user should automatically know that by clicking on the “Yes” button (see Figure 3), the system would proceed to open the curtains.

“It should be designed in a way that users can intuitively navigate. It would simply defeat the purpose if the user needs to spend a lot of time just to figure out what the button does.” – Participant E

It is also suggested that the manipulation should be directed only to the accessibility and not damage the integrity of the availability, which means that the design that uses this method should not limit options.

Reminders Timing is considered to be the most prominent factor for reminders. It is also seen as the “make or break” factor. The users’ condition is usually constantly changing, therefore the delivery of re- minders/notifications should be user-centered and context aware.

“Timing is very important with notifications. For example if I get a notification about working out when I’m about to go home, it might not be very helpful.” – Participant B

According to the participants, attention plays a crucial role, due to the fact that reminders only take effect when users notice them. However, users are often faced with an overwhelming amount of notifications or simply not paying attention to their phones. Two solutions were suggested: prioritizing the notifications and creating cross-platform availability.

“A lot of people don’t really look at them, many are just swiped through or deleted before even being read.” – Participant A

19 “Instead of just delivering notifications through the phone, perhaps there could be some images or reminders that pop up on my TV or laptop screen?” – Participant B

Prompts Prompts was considered a weaker and easily ignored method. In order to overcome limitations such as inattentional blindness, participants advised that prompts could be made more noticeable and emphasized by using brighter colors, lights or purposeful placement,

“This prompt does not seem very persuasive to me. I think you could even be more aggressive and have an explicit note or message” – Participant D

Another concern with prompt is appropriateness. Participants worry that a misplaced prompt may not only be ineffective, but also cause a negative effect. Therefore, designers should be aware of factors such as culture, time of the day, environment and individual differences.

“If you promote alcohol free beer in a German bar, you probably won’t be successful at making people drink less. On the contrary, they might be offended or drink even more.” – Participant D

Framing The participants find the interpretation of framed text to be highly subjective. The same presentation of a message or a piece of information is likely to be received differently. The participants suggested that framing should be context aware, and tailor the style so that it suits different groups of users. For example, in the Meditation scenario, participants had polarized opinions about the text in the notification (see Figure 9).

“Well considering the text, I like that it uses natural language instead of a very stiff tone. It’s always nice to see that.” – Participant B

“It seems a little bit too friendly. I personally would prefer something shorter and neutral.” – Participant C

Pre-commitment Strategies According to the participants, pre-commitment strategies may provide opportunities for users to identify goals from short-term to long-term, depending on the context, and is also considered as a medium for accessing users’ higher-level motivation. In addition, during the goal-setting process, users’ capabilities and conditions should be taken into consideration to avoid frustration.

“The goals should be reasonable, otherwise it is frustrating and simply pointless.” – Participant A

Participants also expressed that pre-commitment strategies alone may not be optimally effective. The influence of pre-commitment strategies can be reinforced with other methods such as reminders and gamification.

“Pre-commitment is certainly good, of course there can be variants. For example, some gamification components can make them more engaged and invested.” – Participant D

20 Discussions

Design Principles Based on the results, five important factors for designing nudges in persuasive technologies were concluded – goal alignment, intuitiveness, context awareness, availability and accessing motivation.

1. Goal alignment: When there is a discrepancy between system and user goals, error arises. There- fore, the designing process of persuasive technologies should be informed by both the knowledge- based objectives and user goals. For example, opening the curtains in the morning and exposing users to natural daylight is great, but the users also have to want to or at least be okay with it for it to be a desirable action. This factor is especially important for non-transparent nudging and the more invasive methods such as default setting. 2. Intuitiveness: Excessively complex systems generate higher cognitive load, they are prone to confusion, fatigue and frustration. Moreover, it defeats the purpose of automatic thinking. Par- ticularly when using Type 1 nudging, it should be designed in such a way that the navigation is easy and intuitive. The instructions, if any, should be clear and concise; the interface should be apparent; and the operation/action should be made simple. As one of the participants stated “It would simply defeat the purpose if the user needs to spend a lot of time just to figure out what the button does.”

3. Context awareness: How nudges are received is influenced by multiple contextual factors, such as timing, culture, individual differences and so on. For nudging to be optimally effective, the design should be aware of the context and take the conditions of the environment into consider- ation. Especially with reminders and other text-based nudging, where the meaning is subject to interpretation.

4. Availability: The essence of nudging is libertarian paternalistic and non-coercive. Therefore, the designs can manipulate accessibility but the integrity of availability should not be damaged. For example, in the Coffee Machine scenario, the purpose is to encourage people to have decaf coffee. It shouldn’t be achieved by taking away the regular coffee option. 5. Accessing motivation: Sustainable behaviour change requires not only behavioural but also at- titudinal changes. Changes in the peripheral may yield immediate results, e.g. default setting. However, these alterations may be conditional. The influence of nudging should go beyond condi- tions and goals and extend its effects to higher level motivation. Type 2 nudging involves reflective thinking, thus providing suitable means to accessing motivation.

Deception in Nudging Even though the freedom of choice is typically preserved, nudging may still lead to deceptive expe- riences in some instances. The deception in nudging can be classified in two categories: deception by non-transparency and self-deception by cognitive biases. When the intentions of the nudges are withheld from users – non-transparent, the influences may go undetected. This is when the behaviour of the system could become deceptive. For example, in the Night Light scenario, the light switch is the same during the day and in the evenings (see Figure 7). An ignorant user may think that they are accessing the regular setting, while it has already been changed to night mode. In cases like this, the non-transparency of the nudges serves as the facilitator of the deceptive behaviour of the system. The other type of deception is a result of the exploitation of cognitive biases such as status quo bias, framing bias and so on. In those cases, nudging takes advantage of users’ heuristics, and the deceptions happen within the users’ belief system and cognitive architecture. Therefore it is considered as self-deception. For example, in The Coffee Break scenario, the first coffee machine indirectly suggested decaf as the primary choice, which may lead William to believe it is the status quo to have decaf coffee.

Effectiveness Versus Autonomy On occasions, people’s choices and behaviours are not entirely driven by knowledge. Our decision making processes are susceptible to deprecating factors such as laziness, procrastination, competing obligations, and absent-mindedness. Especially when cognitive resources are low. One may know what they are supposed to do so that they can have a good night’s sleep, but fail to take action. Type 1 nudging

21 provides convenient and effective means to overcome the aforementioned obstacles. However, there is a trade off between effectiveness and autonomy. A well-designed default setting could save us a lot of time and effort, but it also deprives us of the opportunities to actively make choices. The control over the narrative of decision-making is then shifted toward the designer of such technologies/setting. This seems to pose a threat to our independence and autonomy. One participant said during the interview, “Technologies should be there to help people to be the best versions of themselves, and not trying to take over what they do or how they do things.”, but is it really such a “big deal”? Nudging methods such as default setting and manipulation of accessibility can be found in many facets of our lives and in significantly larger levels, such as organ donation, taxation, consumer behaviour and so on. In my opinion, the real goal here is to obtain justified beliefs that the actions taken are in people’s best interest. And that some sacrifices in autonomy are admissible for the greater good. This dilemma can be well concluded by the words of Cass Sunstein (Sunstein, 2014): “True, it might make sense to ask people to make an active choice, rather than relying on a default rule. But in many contexts, default are indispensable because it is too burdensome and time-consuming to require people to choose.”

Limitations The current study used several detailed scenarios and prototypes to explore the perception of the types and methods of nudging. The advantages of this approach are that it captures context-based/real- life reflections and addresses multiple perspectives at various levels of detailing. However, participants’ judgements about nudging and responses to the prototypes may be affected by the context of the scenarios and the quality of the prototypes. Also, the participants in this study all have academic backgrounds in related fields. Although it provides us opportunities to gain professional insights, we may neglect the viewpoints of regular people, or people of other professions. For example, if the study also included input from health care specialists and engineers, we might be able to get a fuller understanding of how these technologies may be designed and applied.

Conclusions and future work

Conclusion The current study explores the design potentials and the persuasive characteristics of nudging, and we wish to understand how different types and methods of nudging can be applied to persuasive tech- nologies for improving sleep hygiene. The results showed that Type 1 nudging is convenient and effective, but only under the condition of goal alignment. The sense of control is better preserved in Type 2 nudg- ing, and possesses a stronger connection to motivation. However, the effects are limited by attention. Default setting is the most effective nudging method, but prone to error when system and user goals are misaligned. Technologies that use manipulation of accessibility should be designed so that navigation is intuitive. However, the integrity of availability should not be damaged. Timing is the most prominent factor for reminders, and could use cross-platform availability and prioritization to enhance their effects. The presence of prompts can be emphasized by purposeful placement, and appropriateness should be considered. The perception of framing is subjective, therefore it should be tailored and context-aware. Five important factors for nudging-based persuasive technology design were identified from the results: goal alignment, intuitiveness, context awareness, availability and accessing motivation. Finally, nudging provides a behaviour change approach that differs from the ones in existing persuasive technologies. Without being coercive or strictly paternalistic, nudging-based persuasive technologies may allow the multi-factor recommendations of sleep hygiene be reinforced by making them more achievable and promoting motivation, while having users’ freedom of choice and the sense of control intact.

Future Work The attributes and characteristics of the nudging types and methods identified in the results may be used to inform future design processes of technologies that intend to use nudging approaches. And the five design factors – goal alignment, intuitiveness, context awareness, availability and accessing motivation may be used for future studies and research in the nudge theory. The prototypes presented in the current study are still at a conceptual level, there is room for contextualization and embodiment. That being said, there is a considerable potential that these prototypes may be deployed for experimental research.

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